1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
|
drop table if exists t0,t1,t2,t3,t4,t5;
CREATE TABLE t1 (
grp int(11) default NULL,
a bigint(20) unsigned default NULL,
c char(10) NOT NULL default ''
) ENGINE=MyISAM;
INSERT INTO t1 VALUES (1,1,'a'),(2,2,'b'),(2,3,'c'),(3,4,'E'),(3,5,'C'),(3,6,'D'),(NULL,NULL,'');
create table t2 (id int, a bigint unsigned not null, c char(10), d int, primary key (a));
insert into t2 values (1,1,"a",1),(3,4,"A",4),(3,5,"B",5),(3,6,"C",6),(4,7,"D",7);
select t1.*,t2.* from t1 JOIN t2 where t1.a=t2.a;
grp a c id a c d
1 1 a 1 1 a 1
3 4 E 3 4 A 4
3 5 C 3 5 B 5
3 6 D 3 6 C 6
select t1.*,t2.* from t1 left join t2 on (t1.a=t2.a) order by t1.grp,t1.a,t2.c;
grp a c id a c d
NULL NULL NULL NULL NULL NULL
1 1 a 1 1 a 1
2 2 b NULL NULL NULL NULL
2 3 c NULL NULL NULL NULL
3 4 E 3 4 A 4
3 5 C 3 5 B 5
3 6 D 3 6 C 6
select t1.*,t2.* from { oj t2 left outer join t1 on (t1.a=t2.a) };
grp a c id a c d
1 1 a 1 1 a 1
3 4 E 3 4 A 4
3 5 C 3 5 B 5
3 6 D 3 6 C 6
NULL NULL NULL 4 7 D 7
select t1.*,t2.* from t1 as t0,{ oj t2 left outer join t1 on (t1.a=t2.a) } WHERE t0.a=2;
grp a c id a c d
1 1 a 1 1 a 1
3 4 E 3 4 A 4
3 5 C 3 5 B 5
3 6 D 3 6 C 6
NULL NULL NULL 4 7 D 7
select t1.*,t2.* from t1 left join t2 using (a);
grp a c id a c d
1 1 a 1 1 a 1
2 2 b NULL NULL NULL NULL
2 3 c NULL NULL NULL NULL
3 4 E 3 4 A 4
3 5 C 3 5 B 5
3 6 D 3 6 C 6
NULL NULL NULL NULL NULL NULL
select t1.*,t2.* from t1 left join t2 using (a) where t1.a=t2.a;
grp a c id a c d
1 1 a 1 1 a 1
3 4 E 3 4 A 4
3 5 C 3 5 B 5
3 6 D 3 6 C 6
select t1.*,t2.* from t1 left join t2 using (a,c);
grp a c id a c d
1 1 a 1 1 a 1
2 2 b NULL NULL NULL NULL
2 3 c NULL NULL NULL NULL
3 4 E NULL NULL NULL NULL
3 5 C NULL NULL NULL NULL
3 6 D NULL NULL NULL NULL
NULL NULL NULL NULL NULL NULL
select t1.*,t2.* from t1 left join t2 using (c);
grp a c id a c d
1 1 a 1 1 a 1
1 1 a 3 4 A 4
2 2 b 3 5 B 5
2 3 c 3 6 C 6
3 4 E NULL NULL NULL NULL
3 5 C 3 6 C 6
3 6 D 4 7 D 7
NULL NULL NULL NULL NULL NULL
select t1.*,t2.* from t1 natural left outer join t2;
grp a c id a c d
1 1 a 1 1 a 1
2 2 b NULL NULL NULL NULL
2 3 c NULL NULL NULL NULL
3 4 E NULL NULL NULL NULL
3 5 C NULL NULL NULL NULL
3 6 D NULL NULL NULL NULL
NULL NULL NULL NULL NULL NULL
select t1.*,t2.* from t1 left join t2 on (t1.a=t2.a) where t2.id=3;
grp a c id a c d
3 4 E 3 4 A 4
3 5 C 3 5 B 5
3 6 D 3 6 C 6
select t1.*,t2.* from t1 left join t2 on (t1.a=t2.a) where t2.id is null;
grp a c id a c d
2 2 b NULL NULL NULL NULL
2 3 c NULL NULL NULL NULL
NULL NULL NULL NULL NULL NULL
explain select t1.*,t2.* from t1,t2 where t1.a=t2.a and isnull(t2.a)=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
explain select t1.*,t2.* from t1 left join t2 on t1.a=t2.a where isnull(t2.a)=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 7
1 SIMPLE t2 eq_ref PRIMARY PRIMARY 8 test.t1.a 1 Using where
select t1.*,t2.*,t3.a from t1 left join t2 on (t1.a=t2.a) left join t1 as t3 on (t2.a=t3.a);
grp a c id a c d a
1 1 a 1 1 a 1 1
2 2 b NULL NULL NULL NULL NULL
2 3 c NULL NULL NULL NULL NULL
3 4 E 3 4 A 4 4
3 5 C 3 5 B 5 5
3 6 D 3 6 C 6 6
NULL NULL NULL NULL NULL NULL NULL
explain select t1.*,t2.*,t3.a from t1 left join t2 on (t3.a=t2.a) left join t1 as t3 on (t1.a=t3.a);
ERROR 42S22: Unknown column 't3.a' in 'on clause'
select t1.*,t2.*,t3.a from t1 left join t2 on (t3.a=t2.a) left join t1 as t3 on (t1.a=t3.a);
ERROR 42S22: Unknown column 't3.a' in 'on clause'
select t1.*,t2.*,t3.a from t1 left join t2 on (t3.a=t2.a) left join t1 as t3 on (t2.a=t3.a);
ERROR 42S22: Unknown column 't3.a' in 'on clause'
select t1.*,t2.* from t1 inner join t2 using (a);
grp a c id a c d
1 1 a 1 1 a 1
3 4 E 3 4 A 4
3 5 C 3 5 B 5
3 6 D 3 6 C 6
select t1.*,t2.* from t1 inner join t2 on (t1.a=t2.a);
grp a c id a c d
1 1 a 1 1 a 1
3 4 E 3 4 A 4
3 5 C 3 5 B 5
3 6 D 3 6 C 6
select t1.*,t2.* from t1 natural join t2;
grp a c id a c d
1 1 a 1 1 a 1
drop table t1,t2;
CREATE TABLE t1 (
usr_id INT unsigned NOT NULL,
uniq_id INT unsigned NOT NULL AUTO_INCREMENT,
start_num INT unsigned NOT NULL DEFAULT 1,
increment INT unsigned NOT NULL DEFAULT 1,
PRIMARY KEY (uniq_id),
INDEX usr_uniq_idx (usr_id, uniq_id),
INDEX uniq_usr_idx (uniq_id, usr_id)
);
CREATE TABLE t2 (
id INT unsigned NOT NULL DEFAULT 0,
usr2_id INT unsigned NOT NULL DEFAULT 0,
max INT unsigned NOT NULL DEFAULT 0,
c_amount INT unsigned NOT NULL DEFAULT 0,
d_max INT unsigned NOT NULL DEFAULT 0,
d_num INT unsigned NOT NULL DEFAULT 0,
orig_time INT unsigned NOT NULL DEFAULT 0,
c_time INT unsigned NOT NULL DEFAULT 0,
active ENUM ("no","yes") NOT NULL,
PRIMARY KEY (id,usr2_id),
INDEX id_idx (id),
INDEX usr2_idx (usr2_id)
);
INSERT INTO t1 VALUES (3,NULL,0,50),(3,NULL,0,200),(3,NULL,0,25),(3,NULL,0,84676),(3,NULL,0,235),(3,NULL,0,10),(3,NULL,0,3098),(3,NULL,0,2947),(3,NULL,0,8987),(3,NULL,0,8347654),(3,NULL,0,20398),(3,NULL,0,8976),(3,NULL,0,500),(3,NULL,0,198);
SELECT t1.usr_id,t1.uniq_id,t1.increment,
t2.usr2_id,t2.c_amount,t2.max
FROM t1
LEFT JOIN t2 ON t2.id = t1.uniq_id
WHERE t1.uniq_id = 4
ORDER BY t2.c_amount;
usr_id uniq_id increment usr2_id c_amount max
3 4 84676 NULL NULL NULL
SELECT t1.usr_id,t1.uniq_id,t1.increment,
t2.usr2_id,t2.c_amount,t2.max
FROM t2
RIGHT JOIN t1 ON t2.id = t1.uniq_id
WHERE t1.uniq_id = 4
ORDER BY t2.c_amount;
usr_id uniq_id increment usr2_id c_amount max
3 4 84676 NULL NULL NULL
INSERT INTO t2 VALUES (2,3,3000,6000,0,0,746584,837484,'yes');
INSERT INTO t2 VALUES (2,3,3000,6000,0,0,746584,837484,'yes');
ERROR 23000: Duplicate entry '2-3' for key 'PRIMARY'
INSERT INTO t2 VALUES (7,3,1000,2000,0,0,746294,937484,'yes');
SELECT t1.usr_id,t1.uniq_id,t1.increment,t2.usr2_id,t2.c_amount,t2.max FROM t1 LEFT JOIN t2 ON t2.id = t1.uniq_id WHERE t1.uniq_id = 4 ORDER BY t2.c_amount;
usr_id uniq_id increment usr2_id c_amount max
3 4 84676 NULL NULL NULL
SELECT t1.usr_id,t1.uniq_id,t1.increment,t2.usr2_id,t2.c_amount,t2.max FROM t1 LEFT JOIN t2 ON t2.id = t1.uniq_id WHERE t1.uniq_id = 4 GROUP BY t2.c_amount;
usr_id uniq_id increment usr2_id c_amount max
3 4 84676 NULL NULL NULL
SELECT t1.usr_id,t1.uniq_id,t1.increment,t2.usr2_id,t2.c_amount,t2.max FROM t1 LEFT JOIN t2 ON t2.id = t1.uniq_id WHERE t1.uniq_id = 4;
usr_id uniq_id increment usr2_id c_amount max
3 4 84676 NULL NULL NULL
drop table t1,t2;
CREATE TABLE t1 (
cod_asig int(11) DEFAULT '0' NOT NULL,
desc_larga_cat varchar(80) DEFAULT '' NOT NULL,
desc_larga_cas varchar(80) DEFAULT '' NOT NULL,
desc_corta_cat varchar(40) DEFAULT '' NOT NULL,
desc_corta_cas varchar(40) DEFAULT '' NOT NULL,
cred_total double(3,1) DEFAULT '0.0' NOT NULL,
pre_requisit int(11),
co_requisit int(11),
preco_requisit int(11),
PRIMARY KEY (cod_asig)
);
INSERT INTO t1 VALUES (10360,'asdfggfg','Introduccion a los Ordenadores I','asdfggfg','Introduccio Ordinadors I',6.0,NULL,NULL,NULL);
INSERT INTO t1 VALUES (10361,'Components i Circuits Electronics I','Componentes y Circuitos Electronicos I','Components i Circuits Electronics I','Comp. i Circ. Electr. I',6.0,NULL,NULL,NULL);
INSERT INTO t1 VALUES (10362,'Laboratori d`Ordinadors','Laboratorio de Ordenadores','Laboratori d`Ordinadors','Laboratori Ordinadors',4.5,NULL,NULL,NULL);
INSERT INTO t1 VALUES (10363,'Tecniques de Comunicacio Oral i Escrita','Tecnicas de Comunicacion Oral y Escrita','Tecniques de Comunicacio Oral i Escrita','Tec. Com. Oral i Escrita',4.5,NULL,NULL,NULL);
INSERT INTO t1 VALUES (11403,'Projecte Fi de Carrera','Proyecto Fin de Carrera','Projecte Fi de Carrera','PFC',9.0,NULL,NULL,NULL);
INSERT INTO t1 VALUES (11404,'+lgebra lineal','Algebra lineal','+lgebra lineal','+lgebra lineal',15.0,NULL,NULL,NULL);
INSERT INTO t1 VALUES (11405,'+lgebra lineal','Algebra lineal','+lgebra lineal','+lgebra lineal',18.0,NULL,NULL,NULL);
INSERT INTO t1 VALUES (11406,'Calcul Infinitesimal','Cßlculo Infinitesimal','Calcul Infinitesimal','Calcul Infinitesimal',15.0,NULL,NULL,NULL);
CREATE TABLE t2 (
idAssignatura int(11) DEFAULT '0' NOT NULL,
Grup int(11) DEFAULT '0' NOT NULL,
Places smallint(6) DEFAULT '0' NOT NULL,
PlacesOcupades int(11) DEFAULT '0',
PRIMARY KEY (idAssignatura,Grup)
);
INSERT INTO t2 VALUES (10360,12,333,0);
INSERT INTO t2 VALUES (10361,30,2,0);
INSERT INTO t2 VALUES (10361,40,3,0);
INSERT INTO t2 VALUES (10360,45,10,0);
INSERT INTO t2 VALUES (10362,10,12,0);
INSERT INTO t2 VALUES (10360,55,2,0);
INSERT INTO t2 VALUES (10360,70,0,0);
INSERT INTO t2 VALUES (10360,565656,0,0);
INSERT INTO t2 VALUES (10360,32767,7,0);
INSERT INTO t2 VALUES (10360,33,8,0);
INSERT INTO t2 VALUES (10360,7887,85,0);
INSERT INTO t2 VALUES (11405,88,8,0);
INSERT INTO t2 VALUES (10360,0,55,0);
INSERT INTO t2 VALUES (10360,99,0,0);
INSERT INTO t2 VALUES (11411,30,10,0);
INSERT INTO t2 VALUES (11404,0,0,0);
INSERT INTO t2 VALUES (10362,11,111,0);
INSERT INTO t2 VALUES (10363,33,333,0);
INSERT INTO t2 VALUES (11412,55,0,0);
INSERT INTO t2 VALUES (50003,66,6,0);
INSERT INTO t2 VALUES (11403,5,0,0);
INSERT INTO t2 VALUES (11406,11,11,0);
INSERT INTO t2 VALUES (11410,11410,131,0);
INSERT INTO t2 VALUES (11416,11416,32767,0);
INSERT INTO t2 VALUES (11409,0,0,0);
CREATE TABLE t3 (
id int(11) NOT NULL auto_increment,
dni_pasaporte char(16) DEFAULT '' NOT NULL,
idPla int(11) DEFAULT '0' NOT NULL,
cod_asig int(11) DEFAULT '0' NOT NULL,
any smallint(6) DEFAULT '0' NOT NULL,
quatrimestre smallint(6) DEFAULT '0' NOT NULL,
estat char(1) DEFAULT 'M' NOT NULL,
PRIMARY KEY (id),
UNIQUE dni_pasaporte (dni_pasaporte,idPla),
UNIQUE dni_pasaporte_2 (dni_pasaporte,idPla,cod_asig,any,quatrimestre)
);
INSERT INTO t3 VALUES (1,'11111111',1,10362,98,1,'M');
CREATE TABLE t4 (
id int(11) NOT NULL auto_increment,
papa int(11) DEFAULT '0' NOT NULL,
fill int(11) DEFAULT '0' NOT NULL,
idPla int(11) DEFAULT '0' NOT NULL,
PRIMARY KEY (id),
KEY papa (idPla,papa),
UNIQUE papa_2 (idPla,papa,fill)
);
INSERT INTO t4 VALUES (1,-1,10360,1);
INSERT INTO t4 VALUES (2,-1,10361,1);
INSERT INTO t4 VALUES (3,-1,10362,1);
SELECT DISTINCT fill,desc_larga_cat,cred_total,Grup,Places,PlacesOcupades FROM t4 LEFT JOIN t3 ON t3.cod_asig=fill AND estat='S' AND dni_pasaporte='11111111' AND t3.idPla=1 , t2,t1 WHERE fill=t1.cod_asig AND Places>PlacesOcupades AND fill=idAssignatura AND t4.idPla=1 AND papa=-1;
fill desc_larga_cat cred_total Grup Places PlacesOcupades
10360 asdfggfg 6.0 0 55 0
10360 asdfggfg 6.0 12 333 0
10360 asdfggfg 6.0 33 8 0
10360 asdfggfg 6.0 45 10 0
10360 asdfggfg 6.0 55 2 0
10360 asdfggfg 6.0 7887 85 0
10360 asdfggfg 6.0 32767 7 0
10361 Components i Circuits Electronics I 6.0 30 2 0
10361 Components i Circuits Electronics I 6.0 40 3 0
10362 Laboratori d`Ordinadors 4.5 10 12 0
10362 Laboratori d`Ordinadors 4.5 11 111 0
SELECT DISTINCT fill,t3.idPla FROM t4 LEFT JOIN t3 ON t3.cod_asig=t4.fill AND t3.estat='S' AND t3.dni_pasaporte='1234' AND t3.idPla=1 ;
fill idPla
10360 NULL
10361 NULL
10362 NULL
INSERT INTO t3 VALUES (3,'1234',1,10360,98,1,'S');
SELECT DISTINCT fill,t3.idPla FROM t4 LEFT JOIN t3 ON t3.cod_asig=t4.fill AND t3.estat='S' AND t3.dni_pasaporte='1234' AND t3.idPla=1 ;
fill idPla
10360 1
10361 NULL
10362 NULL
drop table t1,t2,t3,test.t4;
CREATE TABLE t1 (
id smallint(5) unsigned NOT NULL auto_increment,
name char(60) DEFAULT '' NOT NULL,
PRIMARY KEY (id)
);
INSERT INTO t1 VALUES (1,'Antonio Paz');
INSERT INTO t1 VALUES (2,'Lilliana Angelovska');
INSERT INTO t1 VALUES (3,'Thimble Smith');
CREATE TABLE t2 (
id smallint(5) unsigned NOT NULL auto_increment,
owner smallint(5) unsigned DEFAULT '0' NOT NULL,
name char(60),
PRIMARY KEY (id)
);
INSERT INTO t2 VALUES (1,1,'El Gato');
INSERT INTO t2 VALUES (2,1,'Perrito');
INSERT INTO t2 VALUES (3,3,'Happy');
select t1.name, t2.name, t2.id from t1 left join t2 on (t1.id = t2.owner);
name name id
Antonio Paz El Gato 1
Antonio Paz Perrito 2
Lilliana Angelovska NULL NULL
Thimble Smith Happy 3
select t1.name, t2.name, t2.id from t1 left join t2 on (t1.id = t2.owner) where t2.id is null;
name name id
Lilliana Angelovska NULL NULL
explain select t1.name, t2.name, t2.id from t1 left join t2 on (t1.id = t2.owner) where t2.id is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ALL NULL NULL NULL NULL 3 Using where; Not exists
explain select t1.name, t2.name, t2.id from t1 left join t2 on (t1.id = t2.owner) where t2.name is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ALL NULL NULL NULL NULL 3 Using where
select count(*) from t1 left join t2 on (t1.id = t2.owner);
count(*)
4
select t1.name, t2.name, t2.id from t2 right join t1 on (t1.id = t2.owner);
name name id
Antonio Paz El Gato 1
Antonio Paz Perrito 2
Lilliana Angelovska NULL NULL
Thimble Smith Happy 3
select t1.name, t2.name, t2.id from t2 right join t1 on (t1.id = t2.owner) where t2.id is null;
name name id
Lilliana Angelovska NULL NULL
explain select t1.name, t2.name, t2.id from t2 right join t1 on (t1.id = t2.owner) where t2.id is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ALL NULL NULL NULL NULL 3 Using where; Not exists
explain select t1.name, t2.name, t2.id from t2 right join t1 on (t1.id = t2.owner) where t2.name is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ALL NULL NULL NULL NULL 3 Using where
select count(*) from t2 right join t1 on (t1.id = t2.owner);
count(*)
4
select t1.name, t2.name, t2.id,t3.id from t2 right join t1 on (t1.id = t2.owner) left join t1 as t3 on t3.id=t2.owner;
name name id id
Antonio Paz El Gato 1 1
Antonio Paz Perrito 2 1
Lilliana Angelovska NULL NULL NULL
Thimble Smith Happy 3 3
select t1.name, t2.name, t2.id,t3.id from t1 right join t2 on (t1.id = t2.owner) right join t1 as t3 on t3.id=t2.owner;
name name id id
Antonio Paz El Gato 1 1
Antonio Paz Perrito 2 1
NULL NULL NULL 2
Thimble Smith Happy 3 3
select t1.name, t2.name, t2.id, t2.owner, t3.id from t1 left join t2 on (t1.id = t2.owner) right join t1 as t3 on t3.id=t2.owner;
name name id owner id
Antonio Paz El Gato 1 1 1
Antonio Paz Perrito 2 1 1
NULL NULL NULL NULL 2
Thimble Smith Happy 3 3 3
drop table t1,t2;
create table t1 (id int not null, str char(10), index(str));
insert into t1 values (1, null), (2, null), (3, "foo"), (4, "bar");
select * from t1 where str is not null order by id;
id str
3 foo
4 bar
select * from t1 where str is null;
id str
1 NULL
2 NULL
drop table t1;
CREATE TABLE t1 (
t1_id bigint(21) NOT NULL auto_increment,
PRIMARY KEY (t1_id)
);
CREATE TABLE t2 (
t2_id bigint(21) NOT NULL auto_increment,
PRIMARY KEY (t2_id)
);
CREATE TABLE t3 (
t3_id bigint(21) NOT NULL auto_increment,
PRIMARY KEY (t3_id)
);
CREATE TABLE t4 (
seq_0_id bigint(21) DEFAULT '0' NOT NULL,
seq_1_id bigint(21) DEFAULT '0' NOT NULL,
KEY seq_0_id (seq_0_id),
KEY seq_1_id (seq_1_id)
);
CREATE TABLE t5 (
seq_0_id bigint(21) DEFAULT '0' NOT NULL,
seq_1_id bigint(21) DEFAULT '0' NOT NULL,
KEY seq_1_id (seq_1_id),
KEY seq_0_id (seq_0_id)
);
insert into t1 values (1);
insert into t2 values (1);
insert into t3 values (1);
insert into t4 values (1,1);
insert into t5 values (1,1);
explain select * from t3 left join t4 on t4.seq_1_id = t2.t2_id left join t1 on t1.t1_id = t4.seq_0_id left join t5 on t5.seq_0_id = t1.t1_id left join t2 on t2.t2_id = t5.seq_1_id where t3.t3_id = 23;
ERROR 42S22: Unknown column 't2.t2_id' in 'on clause'
drop table t1,t2,t3,t4,t5;
create table t1 (n int, m int, o int, key(n));
create table t2 (n int not null, m int, o int, primary key(n));
insert into t1 values (1, 2, 11), (1, 2, 7), (2, 2, 8), (1,2,9),(1,3,9);
insert into t2 values (1, 2, 3),(2, 2, 8), (4,3,9),(3,2,10);
select t1.*, t2.* from t1 left join t2 on t1.n = t2.n and
t1.m = t2.m where t1.n = 1;
n m o n m o
1 2 11 1 2 3
1 2 7 1 2 3
1 2 9 1 2 3
1 3 9 NULL NULL NULL
select t1.*, t2.* from t1 left join t2 on t1.n = t2.n and
t1.m = t2.m where t1.n = 1 order by t1.o;
n m o n m o
1 2 7 1 2 3
1 2 9 1 2 3
1 3 9 NULL NULL NULL
1 2 11 1 2 3
drop table t1,t2;
CREATE TABLE t1 (id1 INT NOT NULL PRIMARY KEY, dat1 CHAR(1), id2 INT);
INSERT INTO t1 VALUES (1,'a',1);
INSERT INTO t1 VALUES (2,'b',1);
INSERT INTO t1 VALUES (3,'c',2);
CREATE TABLE t2 (id2 INT NOT NULL PRIMARY KEY, dat2 CHAR(1));
INSERT INTO t2 VALUES (1,'x');
INSERT INTO t2 VALUES (2,'y');
INSERT INTO t2 VALUES (3,'z');
SELECT t2.id2 FROM t2 LEFT OUTER JOIN t1 ON t1.id2 = t2.id2 WHERE id1 IS NULL;
id2
3
SELECT t2.id2 FROM t2 NATURAL LEFT OUTER JOIN t1 WHERE id1 IS NULL;
id2
3
drop table t1,t2;
create table t1 ( color varchar(20), name varchar(20) );
insert into t1 values ( 'red', 'apple' );
insert into t1 values ( 'yellow', 'banana' );
insert into t1 values ( 'green', 'lime' );
insert into t1 values ( 'black', 'grape' );
insert into t1 values ( 'blue', 'blueberry' );
create table t2 ( count int, color varchar(20) );
insert into t2 values (10, 'green');
insert into t2 values (5, 'black');
insert into t2 values (15, 'white');
insert into t2 values (7, 'green');
select * from t1;
color name
red apple
yellow banana
green lime
black grape
blue blueberry
select * from t2;
count color
10 green
5 black
15 white
7 green
select * from t2 natural join t1;
color count name
green 10 lime
green 7 lime
black 5 grape
select t2.count, t1.name from t2 natural join t1;
count name
10 lime
7 lime
5 grape
select t2.count, t1.name from t2 inner join t1 using (color);
count name
10 lime
7 lime
5 grape
drop table t1;
drop table t2;
CREATE TABLE t1 (
pcode varchar(8) DEFAULT '' NOT NULL
);
INSERT INTO t1 VALUES ('kvw2000'),('kvw2001'),('kvw3000'),('kvw3001'),('kvw3002'),('kvw3500'),('kvw3501'),('kvw3502'),('kvw3800'),('kvw3801'),('kvw3802'),('kvw3900'),('kvw3901'),('kvw3902'),('kvw4000'),('kvw4001'),('kvw4002'),('kvw4200'),('kvw4500'),('kvw5000'),('kvw5001'),('kvw5500'),('kvw5510'),('kvw5600'),('kvw5601'),('kvw6000'),('klw1000'),('klw1020'),('klw1500'),('klw2000'),('klw2001'),('klw2002'),('kld2000'),('klw2500'),('kmw1000'),('kmw1500'),('kmw2000'),('kmw2001'),('kmw2100'),('kmw3000'),('kmw3200');
CREATE TABLE t2 (
pcode varchar(8) DEFAULT '' NOT NULL,
KEY pcode (pcode)
);
INSERT INTO t2 VALUES ('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw6000'),('kvw6000'),('kld2000');
SELECT t1.pcode, IF(ISNULL(t2.pcode), 0, COUNT(*)) AS count FROM t1
LEFT JOIN t2 ON t1.pcode = t2.pcode GROUP BY t1.pcode;
pcode count
kld2000 1
klw1000 0
klw1020 0
klw1500 0
klw2000 0
klw2001 0
klw2002 0
klw2500 0
kmw1000 0
kmw1500 0
kmw2000 0
kmw2001 0
kmw2100 0
kmw3000 0
kmw3200 0
kvw2000 26
kvw2001 0
kvw3000 36
kvw3001 0
kvw3002 0
kvw3500 26
kvw3501 0
kvw3502 0
kvw3800 0
kvw3801 0
kvw3802 0
kvw3900 0
kvw3901 0
kvw3902 0
kvw4000 0
kvw4001 0
kvw4002 0
kvw4200 0
kvw4500 0
kvw5000 0
kvw5001 0
kvw5500 0
kvw5510 0
kvw5600 0
kvw5601 0
kvw6000 2
SELECT SQL_BIG_RESULT t1.pcode, IF(ISNULL(t2.pcode), 0, COUNT(*)) AS count FROM t1 LEFT JOIN t2 ON t1.pcode = t2.pcode GROUP BY t1.pcode;
pcode count
kld2000 1
klw1000 0
klw1020 0
klw1500 0
klw2000 0
klw2001 0
klw2002 0
klw2500 0
kmw1000 0
kmw1500 0
kmw2000 0
kmw2001 0
kmw2100 0
kmw3000 0
kmw3200 0
kvw2000 26
kvw2001 0
kvw3000 36
kvw3001 0
kvw3002 0
kvw3500 26
kvw3501 0
kvw3502 0
kvw3800 0
kvw3801 0
kvw3802 0
kvw3900 0
kvw3901 0
kvw3902 0
kvw4000 0
kvw4001 0
kvw4002 0
kvw4200 0
kvw4500 0
kvw5000 0
kvw5001 0
kvw5500 0
kvw5510 0
kvw5600 0
kvw5601 0
kvw6000 2
drop table t1,t2;
CREATE TABLE t1 (
id int(11),
pid int(11),
rep_del tinyint(4),
KEY id (id),
KEY pid (pid)
);
INSERT INTO t1 VALUES (1,NULL,NULL);
INSERT INTO t1 VALUES (2,1,NULL);
select * from t1 LEFT JOIN t1 t2 ON (t1.id=t2.pid) AND t2.rep_del IS NULL;
id pid rep_del id pid rep_del
1 NULL NULL 2 1 NULL
2 1 NULL NULL NULL NULL
create index rep_del ON t1(rep_del);
select * from t1 LEFT JOIN t1 t2 ON (t1.id=t2.pid) AND t2.rep_del IS NULL;
id pid rep_del id pid rep_del
1 NULL NULL 2 1 NULL
2 1 NULL NULL NULL NULL
drop table t1;
CREATE TABLE t1 (
id int(11) DEFAULT '0' NOT NULL,
name tinytext DEFAULT '' NOT NULL,
UNIQUE id (id)
);
Warnings:
Warning 1101 BLOB/TEXT column 'name' can't have a default value
INSERT INTO t1 VALUES (1,'yes'),(2,'no');
CREATE TABLE t2 (
id int(11) DEFAULT '0' NOT NULL,
idx int(11) DEFAULT '0' NOT NULL,
UNIQUE id (id,idx)
);
INSERT INTO t2 VALUES (1,1);
explain SELECT * from t1 left join t2 on t1.id=t2.id where t2.id IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
1 SIMPLE t2 ref id id 4 test.t1.id 1 Using where; Using index; Not exists
SELECT * from t1 left join t2 on t1.id=t2.id where t2.id IS NULL;
id name id idx
2 no NULL NULL
drop table t1,t2;
create table t1 (bug_id mediumint, reporter mediumint);
create table t2 (bug_id mediumint, who mediumint, index(who));
insert into t2 values (1,1),(1,2);
insert into t1 values (1,1),(2,1);
SELECT * FROM t1 LEFT JOIN t2 ON (t1.bug_id = t2.bug_id AND t2.who = 2) WHERE (t1.reporter = 2 OR t2.who = 2);
bug_id reporter bug_id who
1 1 1 2
drop table t1,t2;
create table t1 (fooID smallint unsigned auto_increment, primary key (fooID));
create table t2 (fooID smallint unsigned not null, barID smallint unsigned not null, primary key (fooID,barID));
insert into t1 (fooID) values (10),(20),(30);
insert into t2 values (10,1),(20,2),(30,3);
explain select * from t2 left join t1 on t1.fooID = t2.fooID and t1.fooID = 30;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL PRIMARY 4 NULL 3 Using index
1 SIMPLE t1 const PRIMARY PRIMARY 2 const 1 Using index
select * from t2 left join t1 on t1.fooID = t2.fooID and t1.fooID = 30;
fooID barID fooID
10 1 NULL
20 2 NULL
30 3 30
select * from t2 left join t1 ignore index(primary) on t1.fooID = t2.fooID and t1.fooID = 30;
fooID barID fooID
10 1 NULL
20 2 NULL
30 3 30
drop table t1,t2;
create table t1 (i int);
create table t2 (i int);
create table t3 (i int);
insert into t1 values(1),(2);
insert into t2 values(2),(3);
insert into t3 values(2),(4);
select * from t1 natural left join t2 natural left join t3;
i
1
2
select * from t1 natural left join t2 where (t2.i is not null)=0;
i
1
select * from t1 natural left join t2 where (t2.i is not null) is not null;
i
1
2
select * from t1 natural left join t2 where (i is not null)=0;
i
select * from t1 natural left join t2 where (i is not null) is not null;
i
1
2
drop table t1,t2,t3;
create table t1 (f1 integer,f2 integer,f3 integer);
create table t2 (f2 integer,f4 integer);
create table t3 (f3 integer,f5 integer);
select * from t1
left outer join t2 using (f2)
left outer join t3 using (f3);
f3 f2 f1 f4 f5
drop table t1,t2,t3;
create table t1 (a1 int, a2 int);
create table t2 (b1 int not null, b2 int);
create table t3 (c1 int, c2 int);
insert into t1 values (1,2), (2,2), (3,2);
insert into t2 values (1,3), (2,3);
insert into t3 values (2,4), (3,4);
select * from t1 left join t2 on b1 = a1 left join t3 on c1 = a1 and b1 is null;
a1 a2 b1 b2 c1 c2
1 2 1 3 NULL NULL
2 2 2 3 NULL NULL
3 2 NULL NULL 3 4
explain select * from t1 left join t2 on b1 = a1 left join t3 on c1 = a1 and b1 is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
1 SIMPLE t3 ALL NULL NULL NULL NULL 2
drop table t1, t2, t3;
create table t1 (
a int(11),
b char(10),
key (a)
);
insert into t1 (a) values (1),(2),(3),(4);
create table t2 (a int);
select * from t1 left join t2 on t1.a=t2.a where not (t2.a <=> t1.a);
a b a
1 NULL NULL
2 NULL NULL
3 NULL NULL
4 NULL NULL
select * from t1 left join t2 on t1.a=t2.a having not (t2.a <=> t1.a);
a b a
1 NULL NULL
2 NULL NULL
3 NULL NULL
4 NULL NULL
drop table t1,t2;
create table t1 (
match_id tinyint(3) unsigned not null auto_increment,
home tinyint(3) unsigned default '0',
unique key match_id (match_id),
key match_id_2 (match_id)
);
insert into t1 values("1", "2");
create table t2 (
player_id tinyint(3) unsigned default '0',
match_1_h tinyint(3) unsigned default '0',
key player_id (player_id)
);
insert into t2 values("1", "5");
insert into t2 values("2", "9");
insert into t2 values("3", "3");
insert into t2 values("4", "7");
insert into t2 values("5", "6");
insert into t2 values("6", "8");
insert into t2 values("7", "4");
insert into t2 values("8", "12");
insert into t2 values("9", "11");
insert into t2 values("10", "10");
explain select s.*, '*', m.*, (s.match_1_h - m.home) UUX from
(t2 s left join t1 m on m.match_id = 1)
order by m.match_id desc;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE s ALL NULL NULL NULL NULL 10 Using temporary; Using filesort
1 SIMPLE m const match_id,match_id_2 match_id 1 const 1
explain select s.*, '*', m.*, (s.match_1_h - m.home) UUX from
(t2 s left join t1 m on m.match_id = 1)
order by UUX desc;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE s ALL NULL NULL NULL NULL 10 Using temporary; Using filesort
1 SIMPLE m const match_id,match_id_2 match_id 1 const 1
select s.*, '*', m.*, (s.match_1_h - m.home) UUX from
(t2 s left join t1 m on m.match_id = 1)
order by UUX desc;
player_id match_1_h * match_id home UUX
8 12 * 1 2 10
9 11 * 1 2 9
10 10 * 1 2 8
2 9 * 1 2 7
6 8 * 1 2 6
4 7 * 1 2 5
5 6 * 1 2 4
1 5 * 1 2 3
7 4 * 1 2 2
3 3 * 1 2 1
explain select s.*, '*', m.*, (s.match_1_h - m.home) UUX from
t2 s straight_join t1 m where m.match_id = 1
order by UUX desc;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE s ALL NULL NULL NULL NULL 10 Using temporary; Using filesort
1 SIMPLE m const match_id,match_id_2 match_id 1 const 1
select s.*, '*', m.*, (s.match_1_h - m.home) UUX from
t2 s straight_join t1 m where m.match_id = 1
order by UUX desc;
player_id match_1_h * match_id home UUX
8 12 * 1 2 10
9 11 * 1 2 9
10 10 * 1 2 8
2 9 * 1 2 7
6 8 * 1 2 6
4 7 * 1 2 5
5 6 * 1 2 4
1 5 * 1 2 3
7 4 * 1 2 2
3 3 * 1 2 1
drop table t1, t2;
create table t1 (a int, b int, unique index idx (a, b));
create table t2 (a int, b int, c int, unique index idx (a, b));
insert into t1 values (1, 10), (1,11), (2,10), (2,11);
insert into t2 values (1,10,3);
select t1.a, t1.b, t2.c from t1 left join t2
on t1.a=t2.a and t1.b=t2.b and t2.c=3
where t1.a=1 and t2.c is null;
a b c
1 11 NULL
drop table t1, t2;
CREATE TABLE t1 (
ts_id bigint(20) default NULL,
inst_id tinyint(4) default NULL,
flag_name varchar(64) default NULL,
flag_value text,
UNIQUE KEY ts_id (ts_id,inst_id,flag_name)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
CREATE TABLE t2 (
ts_id bigint(20) default NULL,
inst_id tinyint(4) default NULL,
flag_name varchar(64) default NULL,
flag_value text,
UNIQUE KEY ts_id (ts_id,inst_id,flag_name)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
INSERT INTO t1 VALUES
(111056548820001, 0, 'flag1', NULL),
(111056548820001, 0, 'flag2', NULL),
(2, 0, 'other_flag', NULL);
INSERT INTO t2 VALUES
(111056548820001, 3, 'flag1', 'sss');
SELECT t1.flag_name,t2.flag_value
FROM t1 LEFT JOIN t2
ON (t1.ts_id = t2.ts_id AND t1.flag_name = t2.flag_name AND
t2.inst_id = 3)
WHERE t1.inst_id = 0 AND t1.ts_id=111056548820001 AND
t2.flag_value IS NULL;
flag_name flag_value
flag2 NULL
DROP TABLE t1,t2;
CREATE TABLE t1 (
id int(11) unsigned NOT NULL auto_increment,
text_id int(10) unsigned default NULL,
PRIMARY KEY (id)
);
INSERT INTO t1 VALUES("1", "0");
INSERT INTO t1 VALUES("2", "10");
CREATE TABLE t2 (
text_id char(3) NOT NULL default '',
language_id char(3) NOT NULL default '',
text_data text,
PRIMARY KEY (text_id,language_id)
);
INSERT INTO t2 VALUES("0", "EN", "0-EN");
INSERT INTO t2 VALUES("0", "SV", "0-SV");
INSERT INTO t2 VALUES("10", "EN", "10-EN");
INSERT INTO t2 VALUES("10", "SV", "10-SV");
SELECT t1.id, t1.text_id, t2.text_data
FROM t1 LEFT JOIN t2
ON t1.text_id = t2.text_id
AND t2.language_id = 'SV'
WHERE (t1.id LIKE '%' OR t2.text_data LIKE '%');
id text_id text_data
1 0 0-SV
2 10 10-SV
DROP TABLE t1, t2;
CREATE TABLE t0 (a0 int PRIMARY KEY);
CREATE TABLE t1 (a1 int PRIMARY KEY);
CREATE TABLE t2 (a2 int);
CREATE TABLE t3 (a3 int);
INSERT INTO t0 VALUES (1);
INSERT INTO t1 VALUES (1);
INSERT INTO t2 VALUES (1), (2);
INSERT INTO t3 VALUES (1), (2);
SELECT * FROM t1 LEFT JOIN t2 ON a1=0;
a1 a2
1 NULL
EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON a1=0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 system NULL NULL NULL NULL 1
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
SELECT * FROM t1 LEFT JOIN (t2,t3) ON a1=0;
a1 a2 a3
1 NULL NULL
EXPLAIN SELECT * FROM t1 LEFT JOIN (t2,t3) ON a1=0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 system NULL NULL NULL NULL 1
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
1 SIMPLE t3 ALL NULL NULL NULL NULL 2
SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=0 WHERE a0=a1;
a0 a1 a2 a3
1 1 NULL NULL
EXPLAIN SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=0 WHERE a0=a1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 system PRIMARY NULL NULL NULL 1
1 SIMPLE t1 system PRIMARY NULL NULL NULL 1
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
1 SIMPLE t3 ALL NULL NULL NULL NULL 2
INSERT INTO t0 VALUES (0);
INSERT INTO t1 VALUES (0);
SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=5 WHERE a0=a1 AND a0=1;
a0 a1 a2 a3
1 1 NULL NULL
EXPLAIN SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=5 WHERE a0=a1 AND a0=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 const PRIMARY PRIMARY 4 const 1 Using index
1 SIMPLE t1 const PRIMARY PRIMARY 4 const 1 Using index
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
1 SIMPLE t3 ALL NULL NULL NULL NULL 2
drop table t1,t2;
create table t1 (a int, b int);
insert into t1 values (1,1),(2,2),(3,3);
create table t2 (a int, b int);
insert into t2 values (1,1), (2,2);
select * from t2 right join t1 on t2.a=t1.a;
a b a b
1 1 1 1
2 2 2 2
NULL NULL 3 3
select straight_join * from t2 right join t1 on t2.a=t1.a;
a b a b
1 1 1 1
2 2 2 2
NULL NULL 3 3
DROP TABLE t0,t1,t2,t3;
CREATE TABLE t1 (a int PRIMARY KEY, b int);
CREATE TABLE t2 (a int PRIMARY KEY, b int);
INSERT INTO t1 VALUES (1,1), (2,1), (3,1), (4,2);
INSERT INTO t2 VALUES (1,2), (2,2);
SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.a;
a b a b
1 1 1 2
2 1 2 2
3 1 NULL NULL
4 2 NULL NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.a WHERE t1.b=1;
a b a b
1 1 1 2
2 1 2 2
3 1 NULL NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
WHERE t1.b=1 XOR (NOT ISNULL(t2.a) AND t2.b=1);
a b a b
1 1 1 2
2 1 2 2
3 1 NULL NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.a WHERE not(0+(t1.a=30 and t2.b=1));
a b a b
1 1 1 2
2 1 2 2
3 1 NULL NULL
4 2 NULL NULL
DROP TABLE t1,t2;
set group_concat_max_len=5;
create table t1 (a int, b varchar(20));
create table t2 (a int, c varchar(20));
insert into t1 values (1,"aaaaaaaaaa"),(2,"bbbbbbbbbb");
insert into t2 values (1,"cccccccccc"),(2,"dddddddddd");
select group_concat(t1.b,t2.c) from t1 left join t2 using(a) group by t1.a;
group_concat(t1.b,t2.c)
aaaaa
bbbbb
Warnings:
Warning 1260 2 line(s) were cut by GROUP_CONCAT()
select group_concat(t1.b,t2.c) from t1 inner join t2 using(a) group by t1.a;
group_concat(t1.b,t2.c)
aaaaa
bbbbb
Warnings:
Warning 1260 2 line(s) were cut by GROUP_CONCAT()
select group_concat(t1.b,t2.c) from t1 left join t2 using(a) group by a;
group_concat(t1.b,t2.c)
aaaaa
bbbbb
Warnings:
Warning 1260 2 line(s) were cut by GROUP_CONCAT()
select group_concat(t1.b,t2.c) from t1 inner join t2 using(a) group by a;
group_concat(t1.b,t2.c)
aaaaa
bbbbb
Warnings:
Warning 1260 2 line(s) were cut by GROUP_CONCAT()
drop table t1, t2;
set group_concat_max_len=default;
create table t1 (gid smallint(5) unsigned not null, x int(11) not null, y int(11) not null, art int(11) not null, primary key (gid,x,y));
insert t1 values (1, -5, -8, 2), (1, 2, 2, 1), (1, 1, 1, 1);
create table t2 (gid smallint(5) unsigned not null, x int(11) not null, y int(11) not null, id int(11) not null, primary key (gid,id,x,y), key id (id));
insert t2 values (1, -5, -8, 1), (1, 1, 1, 1), (1, 2, 2, 1);
create table t3 ( set_id smallint(5) unsigned not null, id tinyint(4) unsigned not null, name char(12) not null, primary key (id,set_id));
insert t3 values (0, 1, 'a'), (1, 1, 'b'), (0, 2, 'c'), (1, 2, 'd'), (1, 3, 'e'), (1, 4, 'f'), (1, 5, 'g'), (1, 6, 'h');
explain select name from t1 left join t2 on t1.x = t2.x and t1.y = t2.y
left join t3 on t1.art = t3.id where t2.id =1 and t2.x = -5 and t2.y =-8
and t1.gid =1 and t2.gid =1 and t3.set_id =1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 const PRIMARY PRIMARY 10 const,const,const 1
1 SIMPLE t2 const PRIMARY,id PRIMARY 14 const,const,const,const 1 Using index
1 SIMPLE t3 const PRIMARY PRIMARY 3 const,const 1
drop tables t1,t2,t3;
CREATE TABLE t1 (c11 int);
CREATE TABLE t2 (c21 int);
INSERT INTO t1 VALUES (30), (40), (50);
INSERT INTO t2 VALUES (300), (400), (500);
SELECT * FROM t1 LEFT JOIN t2 ON (c11=c21 AND c21=30) WHERE c11=40;
c11 c21
40 NULL
DROP TABLE t1, t2;
CREATE TABLE t1 (a int PRIMARY KEY, b int);
CREATE TABLE t2 (a int PRIMARY KEY, b int);
INSERT INTO t1 VALUES (1,2), (2,1), (3,2), (4,3), (5,6), (6,5), (7,8), (8,7), (9,10);
INSERT INTO t2 VALUES (3,0), (4,1), (6,4), (7,5);
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t2.b <= t1.a AND t1.a <= t1.b;
a b a b
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a BETWEEN t2.b AND t1.b;
a b a b
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a NOT BETWEEN t2.b AND t1.b);
a b a b
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t2.b > t1.a OR t1.a > t1.b;
a b a b
2 1 NULL NULL
3 2 3 0
4 3 4 1
6 5 6 4
8 7 NULL NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a NOT BETWEEN t2.b AND t1.b;
a b a b
2 1 NULL NULL
3 2 3 0
4 3 4 1
6 5 6 4
8 7 NULL NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a BETWEEN t2.b AND t1.b);
a b a b
2 1 NULL NULL
3 2 3 0
4 3 4 1
6 5 6 4
8 7 NULL NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t2.b > t1.a OR t1.a > t1.b;
a b a b
2 1 NULL NULL
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
8 7 NULL NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a != t2.a AND t1.a BETWEEN t2.b AND t1.b);
a b a b
2 1 NULL NULL
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
8 7 NULL NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a AND (t2.b > t1.a OR t1.a > t1.b);
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a != t2.a OR t1.a BETWEEN t2.b AND t1.b);
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t1.a = t2.b;
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a IN(t2.a, t2.b);
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a NOT IN(t2.a, t2.b));
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a != t1.b AND t1.a != t2.b;
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a NOT IN(t1.b, t2.b);
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a IN(t1.b, t2.b));
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t2.a != t2.b OR (t1.a != t2.a AND t1.a != t2.b);
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t2.a = t2.b AND t1.a IN(t2.a, t2.b));
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t2.a != t2.b AND t1.a != t1.b AND t1.a != t2.b;
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t2.a = t2.b OR t1.a IN(t1.b, t2.b));
a b a b
3 2 3 0
4 3 4 1
6 5 6 4
7 8 7 5
EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t1.a = t2.b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 4
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.a 1
EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a IN(t2.a, t2.b);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 4 Using where
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.a 1
EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a > IF(t1.a = t2.b-2, t2.b, t2.b-1);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 4 Using where
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.a 1
DROP TABLE t1,t2;
CREATE TABLE t1 (a int);
CREATE TABLE t2 (b int);
INSERT INTO t1 VALUES (1), (2), (3), (4);
INSERT INTO t2 VALUES (2), (3);
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1);
a b
1 NULL
2 2
3 3
4 NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1 OR 1);
a b
1 NULL
2 2
3 3
4 NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (0 OR 1);
a b
1 NULL
2 2
3 3
4 NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1 OR 2=2);
a b
1 NULL
2 2
3 3
4 NULL
SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1 OR 1=0);
a b
1 NULL
2 2
3 3
4 NULL
DROP TABLE t1,t2;
CREATE TABLE t1 (
f1 varchar(16) collate latin1_swedish_ci PRIMARY KEY,
f2 varchar(16) collate latin1_swedish_ci
);
CREATE TABLE t2 (
f1 varchar(16) collate latin1_swedish_ci PRIMARY KEY,
f3 varchar(16) collate latin1_swedish_ci
);
INSERT INTO t1 VALUES ('bla','blah');
INSERT INTO t2 VALUES ('bla','sheep');
SELECT * FROM t1 JOIN t2 USING(f1) WHERE f1='Bla';
f1 f2 f3
bla blah sheep
SELECT * FROM t1 LEFT JOIN t2 USING(f1) WHERE f1='bla';
f1 f2 f3
bla blah sheep
SELECT * FROM t1 LEFT JOIN t2 USING(f1) WHERE f1='Bla';
f1 f2 f3
bla blah sheep
DROP TABLE t1,t2;
CREATE TABLE t1 (id int PRIMARY KEY, a varchar(8));
CREATE TABLE t2 (id int NOT NULL, b int NOT NULL, INDEX idx(id));
INSERT INTO t1 VALUES
(1,'aaaaaaa'), (5,'eeeeeee'), (4,'ddddddd'), (2,'bbbbbbb'), (3,'ccccccc');
INSERT INTO t2 VALUES
(3,10), (2,20), (5,30), (3,20), (5,10), (3,40), (3,30), (2,10), (2,40);
EXPLAIN
SELECT t1.id, a FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.b IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 5
1 SIMPLE t2 ref idx idx 4 test.t1.id 2 Using where; Not exists
flush status;
SELECT t1.id, a FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.b IS NULL;
id a
1 aaaaaaa
4 ddddddd
show status like 'Handler_read%';
Variable_name Value
Handler_read_first 0
Handler_read_key 5
Handler_read_next 0
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 6
DROP TABLE t1,t2;
CREATE TABLE t1 (c int PRIMARY KEY, e int NOT NULL);
INSERT INTO t1 VALUES (1,0), (2,1);
CREATE TABLE t2 (d int PRIMARY KEY);
INSERT INTO t2 VALUES (1), (2), (3);
EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 const PRIMARY PRIMARY 4 const 1
1 SIMPLE t2 index NULL PRIMARY 4 NULL 3 Using where; Using index; Not exists
SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d IS NULL;
c e d
1 0 NULL
SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d<=>NULL;
c e d
1 0 NULL
DROP TABLE t1,t2;
|