1
drop table if exists t1,t2;
2
create table t1 (a int, b int not null,unique key (a,b),index(b)) engine=myisam;
3
insert ignore into t1 values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(null,7),(9,9),(8,8),(7,7),(null,9),(null,9),(6,6);
4
explain select * from t1 where a is null;
5
id select_type table type possible_keys key key_len ref rows Extra
6
1 SIMPLE t1 ref a a 5 const 3 Using where; Using index
7
explain select * from t1 where a is null and b = 2;
8
id select_type table type possible_keys key key_len ref rows Extra
9
1 SIMPLE t1 ref a,b a 9 const,const 1 Using where; Using index
10
explain select * from t1 where a is null and b = 7;
11
id select_type table type possible_keys key key_len ref rows Extra
12
1 SIMPLE t1 ref a,b a 9 const,const 1 Using where; Using index
13
explain select * from t1 where a=2 and b = 2;
14
id select_type table type possible_keys key key_len ref rows Extra
15
1 SIMPLE t1 const a,b a 9 const,const 1 Using index
16
explain select * from t1 where a<=>b limit 2;
17
id select_type table type possible_keys key key_len ref rows Extra
18
1 SIMPLE t1 index NULL a 9 NULL 12 Using where; Using index
19
explain select * from t1 where (a is null or a > 0 and a < 3) and b < 5 limit 3;
20
id select_type table type possible_keys key key_len ref rows Extra
21
1 SIMPLE t1 range a,b a 9 NULL 3 Using where; Using index
22
explain select * from t1 where (a is null or a = 7) and b=7;
23
id select_type table type possible_keys key key_len ref rows Extra
24
1 SIMPLE t1 ref_or_null a,b a 9 const,const 2 Using index
25
explain select * from t1 where (a is null or a = 7) and b=7 order by a;
26
id select_type table type possible_keys key key_len ref rows Extra
27
1 SIMPLE t1 ref_or_null a,b a 9 const,const 2 Using index; Using filesort
28
explain select * from t1 where (a is null and b>a) or a is null and b=7 limit 2;
29
id select_type table type possible_keys key key_len ref rows Extra
30
1 SIMPLE t1 ref a,b a 5 const 3 Using where; Using index
31
explain select * from t1 where a is null and b=9 or a is null and b=7 limit 3;
32
id select_type table type possible_keys key key_len ref rows Extra
33
1 SIMPLE t1 range a,b a 9 NULL 3 Using where; Using index
34
explain select * from t1 where a > 1 and a < 3 limit 1;
35
id select_type table type possible_keys key key_len ref rows Extra
36
1 SIMPLE t1 range a a 5 NULL 1 Using where; Using index
37
explain select * from t1 where a > 8 and a < 9;
38
id select_type table type possible_keys key key_len ref rows Extra
39
1 SIMPLE t1 range a a 5 NULL 1 Using where; Using index
40
select * from t1 where a is null;
45
select * from t1 where a is null and b = 7;
48
select * from t1 where a<=>b limit 2;
52
select * from t1 where (a is null or a > 0 and a < 3) and b < 5 limit 3;
56
select * from t1 where (a is null or a > 0 and a < 3) and b > 7 limit 3;
60
select * from t1 where (a is null or a = 7) and b=7;
64
select * from t1 where a is null and b=9 or a is null and b=7 limit 3;
69
select * from t1 where a > 1 and a < 3 limit 1;
72
select * from t1 where a > 8 and a < 9;
74
create table t2 like t1;
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insert into t2 select * from t1;
76
alter table t1 modify b blob not null, add c int not null, drop key a, add unique key (a,b(20),c), drop key b, add key (b(10));
77
explain select * from t1 where a is null and b = 2;
78
id select_type table type possible_keys key key_len ref rows Extra
79
1 SIMPLE t1 ref a,b a 5 const 3 Using where
80
explain select * from t1 where a is null and b = 2 and c=0;
81
id select_type table type possible_keys key key_len ref rows Extra
82
1 SIMPLE t1 ref a,b a 5 const 3 Using where
83
explain select * from t1 where a is null and b = 7 and c=0;
84
id select_type table type possible_keys key key_len ref rows Extra
85
1 SIMPLE t1 ref a,b a 5 const 3 Using where
86
explain select * from t1 where a=2 and b = 2;
87
id select_type table type possible_keys key key_len ref rows Extra
88
1 SIMPLE t1 ref a,b a 5 const 1 Using where
89
explain select * from t1 where a<=>b limit 2;
90
id select_type table type possible_keys key key_len ref rows Extra
91
1 SIMPLE t1 ALL NULL NULL NULL NULL 12 Using where
92
explain select * from t1 where (a is null or a > 0 and a < 3) and b < 5 and c=0 limit 3;
93
id select_type table type possible_keys key key_len ref rows Extra
94
1 SIMPLE t1 range a,b a 5 NULL 5 Using where
95
explain select * from t1 where (a is null or a = 7) and b=7 and c=0;
96
id select_type table type possible_keys key key_len ref rows Extra
97
1 SIMPLE t1 ref_or_null a,b a 5 const 4 Using where
98
explain select * from t1 where (a is null and b>a) or a is null and b=7 limit 2;
99
id select_type table type possible_keys key key_len ref rows Extra
100
1 SIMPLE t1 ref a,b a 5 const 3 Using where
101
explain select * from t1 where a is null and b=9 or a is null and b=7 limit 3;
102
id select_type table type possible_keys key key_len ref rows Extra
103
1 SIMPLE t1 ref a,b a 5 const 3 Using where
104
explain select * from t1 where a > 1 and a < 3 limit 1;
105
id select_type table type possible_keys key key_len ref rows Extra
106
1 SIMPLE t1 range a a 5 NULL 1 Using where
107
explain select * from t1 where a is null and b=7 or a > 1 and a < 3 limit 1;
108
id select_type table type possible_keys key key_len ref rows Extra
109
1 SIMPLE t1 range a,b a 5 NULL 4 Using where
110
explain select * from t1 where a > 8 and a < 9;
111
id select_type table type possible_keys key key_len ref rows Extra
112
1 SIMPLE t1 range a a 5 NULL 1 Using where
113
explain select * from t1 where b like "6%";
114
id select_type table type possible_keys key key_len ref rows Extra
115
1 SIMPLE t1 range b b 12 NULL 1 Using where
116
select * from t1 where a is null;
121
select * from t1 where a is null and b = 7 and c=0;
124
select * from t1 where a<=>b limit 2;
128
select * from t1 where (a is null or a > 0 and a < 3) and b < 5 limit 3;
132
select * from t1 where (a is null or a > 0 and a < 3) and b > 7 limit 3;
136
select * from t1 where (a is null or a = 7) and b=7 and c=0;
140
select * from t1 where a is null and b=9 or a is null and b=7 limit 3;
145
select * from t1 where b like "6%";
149
rename table t2 to t1;
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alter table t1 modify b int null;
151
insert into t1 values (7,null), (8,null), (8,7);
152
explain select * from t1 where a = 7 and (b=7 or b is null);
153
id select_type table type possible_keys key key_len ref rows Extra
154
1 SIMPLE t1 ref_or_null a,b a 10 const,const 2 Using index
155
select * from t1 where a = 7 and (b=7 or b is null);
159
explain select * from t1 where (a = 7 or a is null) and (b=7 or b is null);
160
id select_type table type possible_keys key key_len ref rows Extra
161
1 SIMPLE t1 ref_or_null a,b a 5 const 4 Using where; Using index
162
select * from t1 where (a = 7 or a is null) and (b=7 or b is null);
167
explain select * from t1 where (a = 7 or a is null) and (a = 7 or a is null);
168
id select_type table type possible_keys key key_len ref rows Extra
169
1 SIMPLE t1 ref_or_null a a 5 const 5 Using index
170
select * from t1 where (a = 7 or a is null) and (a = 7 or a is null);
177
create table t2 (a int);
178
insert into t2 values (7),(8);
179
explain select * from t2 straight_join t1 where t1.a=t2.a and b is null;
180
id select_type table type possible_keys key key_len ref rows Extra
181
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
182
1 SIMPLE t1 ref a,b a 10 test.t2.a,const 2 Using where; Using index
184
explain select * from t2,t1 where t1.a=t2.a and b is null;
185
id select_type table type possible_keys key key_len ref rows Extra
186
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
187
1 SIMPLE t1 ref a a 10 test.t2.a,const 2 Using where; Using index
188
select * from t2,t1 where t1.a=t2.a and b is null;
192
explain select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null);
193
id select_type table type possible_keys key key_len ref rows Extra
194
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
195
1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const 4 Using index
196
select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null);
202
explain select * from t2,t1 where (t1.a=t2.a or t1.a is null) and b= 7;
203
id select_type table type possible_keys key key_len ref rows Extra
204
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
205
1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const 4 Using index
206
select * from t2,t1 where (t1.a=t2.a or t1.a is null) and b= 7;
212
explain select * from t2,t1 where (t1.a=t2.a or t1.a is null) and (b= 7 or b is null);
213
id select_type table type possible_keys key key_len ref rows Extra
214
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
215
1 SIMPLE t1 ref_or_null a a 5 test.t2.a 4 Using where; Using index
216
select * from t2,t1 where (t1.a=t2.a or t1.a is null) and (b= 7 or b is null);
224
insert into t2 values (null),(6);
225
delete from t1 where a=8;
226
explain select * from t2,t1 where t1.a=t2.a or t1.a is null;
227
id select_type table type possible_keys key key_len ref rows Extra
228
1 SIMPLE t2 ALL NULL NULL NULL NULL 4
229
1 SIMPLE t1 ref_or_null a a 5 test.t2.a 4 Using index
230
explain select * from t2,t1 where t1.a<=>t2.a or (t1.a is null and t1.b <> 9);
231
id select_type table type possible_keys key key_len ref rows Extra
232
1 SIMPLE t2 ALL NULL NULL NULL NULL 4
233
1 SIMPLE t1 ref_or_null a a 5 test.t2.a 4 Using where; Using index
234
select * from t2,t1 where t1.a<=>t2.a or (t1.a is null and t1.b <> 9);
247
id int(10) unsigned NOT NULL auto_increment,
248
uniq_id int(10) unsigned default NULL,
250
UNIQUE KEY idx1 (uniq_id)
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id int(10) unsigned NOT NULL auto_increment,
254
uniq_id int(10) unsigned default NULL,
257
INSERT INTO t1 VALUES (1,NULL),(2,NULL),(3,1),(4,2),(5,NULL),(6,NULL),(7,3),(8,4),(9,NULL),(10,NULL);
258
INSERT INTO t2 VALUES (1,NULL),(2,NULL),(3,1),(4,2),(5,NULL),(6,NULL),(7,3),(8,4),(9,NULL),(10,NULL);
259
explain select id from t1 where uniq_id is null;
260
id select_type table type possible_keys key key_len ref rows Extra
261
1 SIMPLE t1 ref idx1 idx1 5 const 5 Using index condition
262
explain select id from t1 where uniq_id =1;
263
id select_type table type possible_keys key key_len ref rows Extra
264
1 SIMPLE t1 const idx1 idx1 5 const 1
265
UPDATE t1 SET id=id+100 where uniq_id is null;
266
UPDATE t2 SET id=id+100 where uniq_id is null;
267
select id from t1 where uniq_id is null;
275
select id from t2 where uniq_id is null;
283
DELETE FROM t1 WHERE uniq_id IS NULL;
284
DELETE FROM t2 WHERE uniq_id IS NULL;
285
SELECT * FROM t1 ORDER BY uniq_id, id;
291
SELECT * FROM t2 ORDER BY uniq_id, id;
299
`order_id` char(32) NOT NULL default '',
300
`product_id` char(32) NOT NULL default '',
301
`product_type` int(11) NOT NULL default '0',
302
PRIMARY KEY (`order_id`,`product_id`,`product_type`)
305
`order_id` char(32) NOT NULL default '',
306
`product_id` char(32) NOT NULL default '',
307
`product_type` int(11) NOT NULL default '0',
308
PRIMARY KEY (`order_id`,`product_id`,`product_type`)
310
INSERT INTO t1 (order_id, product_id, product_type) VALUES
311
('3d7ce39b5d4b3e3d22aaafe9b633de51',1206029, 3),
312
('3d7ce39b5d4b3e3d22aaafe9b633de51',5880836, 3),
313
('9d9aad7764b5b2c53004348ef8d34500',2315652, 3);
314
INSERT INTO t2 (order_id, product_id, product_type) VALUES
315
('9d9aad7764b5b2c53004348ef8d34500',2315652, 3);
317
left join t2 using(order_id, product_id, product_type)
318
where t2.order_id=NULL;
319
order_id product_id product_type
321
left join t2 using(order_id, product_id, product_type)
322
where t2.order_id is NULL;
323
order_id product_id product_type
324
3d7ce39b5d4b3e3d22aaafe9b633de51 1206029 3
325
3d7ce39b5d4b3e3d22aaafe9b633de51 5880836 3
327
create table t1 (id int);
328
insert into t1 values (null), (0);
329
create table t2 (id int);
330
insert into t2 values (null);
331
select * from t1, t2 where t1.id = t2.id;
333
alter table t1 add key id (id);
334
select * from t1, t2 where t1.id = t2.id;
339
id2 integer not null,
343
insert into t1 values(null,null),(1,1);
345
Warning 1048 Column 'id2' cannot be null
350
select * from t1 where id <=> null;
353
select * from t1 where id <=> null or id > 0;
357
select * from t1 where id is null or id > 0;
361
select * from t1 where id2 <=> null or id2 > 0;
364
select * from t1 where id2 is null or id2 > 0;
367
delete from t1 where id <=> NULL;
372
CREATE TABLE t1 (a int);
373
CREATE TABLE t2 (a int, b int, INDEX idx(a));
374
CREATE TABLE t3 (b int, INDEX idx(b));
375
CREATE TABLE t4 (b int, INDEX idx(b));
376
INSERT INTO t1 VALUES (1), (2), (3), (4);
377
INSERT INTO t2 VALUES (1, 1), (3, 1);
378
INSERT INTO t3 VALUES
379
(NULL), (NULL), (NULL), (NULL), (NULL),
380
(NULL), (NULL), (NULL), (NULL), (NULL);
381
INSERT INTO t4 SELECT * FROM t3;
382
INSERT INTO t3 SELECT * FROM t4;
383
INSERT INTO t4 SELECT * FROM t3;
384
INSERT INTO t3 SELECT * FROM t4;
385
INSERT INTO t4 SELECT * FROM t3;
386
INSERT INTO t3 SELECT * FROM t4;
387
INSERT INTO t4 SELECT * FROM t3;
388
INSERT INTO t3 SELECT * FROM t4;
389
INSERT INTO t4 SELECT * FROM t3;
390
INSERT INTO t3 SELECT * FROM t4;
391
INSERT INTO t4 SELECT * FROM t3;
392
INSERT INTO t3 SELECT * FROM t4;
393
INSERT INTO t4 SELECT * FROM t3;
394
INSERT INTO t3 SELECT * FROM t4;
395
INSERT INTO t4 SELECT * FROM t3;
396
INSERT INTO t3 SELECT * FROM t4;
397
INSERT INTO t3 VALUES (2), (3);
398
ANALYZE table t1, t2, t3;
399
Table Op Msg_type Msg_text
400
test.t1 analyze status OK
401
test.t2 analyze status OK
402
test.t3 analyze status OK
403
SELECT COUNT(*) FROM t3;
406
EXPLAIN SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
407
LEFT JOIN t3 ON t2.b=t3.b;
408
id select_type table type possible_keys key key_len ref rows Extra
409
1 SIMPLE t1 ALL NULL NULL NULL NULL 4
410
1 SIMPLE t2 ref idx idx 5 test.t1.a 1
411
1 SIMPLE t3 ref idx idx 5 test.t2.b 1 Using index
413
SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
414
LEFT JOIN t3 ON t2.b=t3.b;
423
SHOW STATUS LIKE "handler_read%";
430
Handler_read_rnd_next 5
431
DROP TABLE t1,t2,t3,t4;
433
a int(11) default NULL,
434
b int(11) default NULL,
437
INSERT INTO t1 VALUES (0,10),(0,11),(0,12);
439
a int(11) default NULL,
440
b int(11) default NULL,
443
INSERT INTO t2 VALUES (3,NULL),(3,11),(3,12);
444
SELECT * FROM t2 inner join t1 WHERE ( t1.a = 0 OR t1.a IS NULL) AND t2.a = 3 AND t2.b = t1.b;