|
1
by brian
clean slate |
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; |
|
41 |
a b |
|
42 |
NULL 7 |
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43 |
NULL 9 |
|
44 |
NULL 9 |
|
45 |
select * from t1 where a is null and b = 7; |
|
46 |
a b |
|
47 |
NULL 7 |
|
48 |
select * from t1 where a<=>b limit 2; |
|
49 |
a b |
|
50 |
1 1 |
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51 |
2 2 |
|
52 |
select * from t1 where (a is null or a > 0 and a < 3) and b < 5 limit 3; |
|
53 |
a b |
|
54 |
1 1 |
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55 |
2 2 |
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56 |
select * from t1 where (a is null or a > 0 and a < 3) and b > 7 limit 3; |
|
57 |
a b |
|
58 |
NULL 9 |
|
59 |
NULL 9 |
|
60 |
select * from t1 where (a is null or a = 7) and b=7; |
|
61 |
a b |
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62 |
7 7 |
|
63 |
NULL 7 |
|
64 |
select * from t1 where a is null and b=9 or a is null and b=7 limit 3; |
|
65 |
a b |
|
66 |
NULL 7 |
|
67 |
NULL 9 |
|
68 |
NULL 9 |
|
69 |
select * from t1 where a > 1 and a < 3 limit 1; |
|
70 |
a b |
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71 |
2 2 |
|
72 |
select * from t1 where a > 8 and a < 9; |
|
73 |
a b |
|
74 |
create table t2 like t1; |
|
75 |
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; |
|
117 |
a b c |
|
118 |
NULL 7 0 |
|
119 |
NULL 9 0 |
|
120 |
NULL 9 0 |
|
121 |
select * from t1 where a is null and b = 7 and c=0; |
|
122 |
a b c |
|
123 |
NULL 7 0 |
|
124 |
select * from t1 where a<=>b limit 2; |
|
125 |
a b c |
|
126 |
1 1 0 |
|
127 |
2 2 0 |
|
128 |
select * from t1 where (a is null or a > 0 and a < 3) and b < 5 limit 3; |
|
129 |
a b c |
|
130 |
1 1 0 |
|
131 |
2 2 0 |
|
132 |
select * from t1 where (a is null or a > 0 and a < 3) and b > 7 limit 3; |
|
133 |
a b c |
|
134 |
NULL 9 0 |
|
135 |
NULL 9 0 |
|
136 |
select * from t1 where (a is null or a = 7) and b=7 and c=0; |
|
137 |
a b c |
|
138 |
7 7 0 |
|
139 |
NULL 7 0 |
|
140 |
select * from t1 where a is null and b=9 or a is null and b=7 limit 3; |
|
141 |
a b c |
|
142 |
NULL 7 0 |
|
143 |
NULL 9 0 |
|
144 |
NULL 9 0 |
|
145 |
select * from t1 where b like "6%"; |
|
146 |
a b c |
|
147 |
6 6 0 |
|
148 |
drop table t1; |
|
149 |
rename table t2 to t1; |
|
150 |
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); |
|
156 |
a b |
|
157 |
7 7 |
|
158 |
7 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); |
|
163 |
a b |
|
164 |
7 NULL |
|
165 |
7 7 |
|
166 |
NULL 7 |
|
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); |
|
171 |
a b |
|
172 |
7 NULL |
|
173 |
7 7 |
|
174 |
NULL 7 |
|
175 |
NULL 9 |
|
176 |
NULL 9 |
|
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 |
|
183 |
drop index b on t1; |
|
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; |
|
189 |
a a b |
|
190 |
7 7 NULL |
|
191 |
8 8 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); |
|
197 |
a a b |
|
198 |
7 7 7 |
|
199 |
7 7 NULL |
|
200 |
8 8 7 |
|
201 |
8 8 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; |
|
207 |
a a b |
|
208 |
7 7 7 |
|
209 |
7 NULL 7 |
|
210 |
8 8 7 |
|
211 |
8 NULL 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); |
|
217 |
a a b |
|
218 |
7 7 NULL |
|
219 |
7 7 7 |
|
220 |
7 NULL 7 |
|
221 |
8 8 NULL |
|
222 |
8 8 7 |
|
223 |
8 NULL 7 |
|
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); |
|
235 |
a a b |
|
236 |
7 7 NULL |
|
237 |
7 7 7 |
|
238 |
7 NULL 7 |
|
239 |
8 NULL 7 |
|
240 |
NULL NULL 7 |
|
241 |
NULL NULL 9 |
|
242 |
NULL NULL 9 |
|
243 |
6 6 6 |
|
244 |
6 NULL 7 |
|
245 |
drop table t1,t2; |
|
246 |
CREATE TABLE t1 ( |
|
247 |
id int(10) unsigned NOT NULL auto_increment, |
|
248 |
uniq_id int(10) unsigned default NULL, |
|
249 |
PRIMARY KEY (id), |
|
250 |
UNIQUE KEY idx1 (uniq_id) |
|
251 |
) ENGINE=MyISAM; |
|
252 |
CREATE TABLE t2 ( |
|
253 |
id int(10) unsigned NOT NULL auto_increment, |
|
254 |
uniq_id int(10) unsigned default NULL, |
|
255 |
PRIMARY KEY (id) |
|
256 |
) ENGINE=MyISAM; |
|
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; |
|
268 |
id
|
|
269 |
101
|
|
270 |
102
|
|
271 |
105
|
|
272 |
106
|
|
273 |
109
|
|
274 |
110
|
|
275 |
select id from t2 where uniq_id is null; |
|
276 |
id
|
|
277 |
101
|
|
278 |
102
|
|
279 |
105
|
|
280 |
106
|
|
281 |
109
|
|
282 |
110
|
|
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; |
|
286 |
id uniq_id |
|
287 |
3 1 |
|
288 |
4 2 |
|
289 |
7 3 |
|
290 |
8 4 |
|
291 |
SELECT * FROM t2 ORDER BY uniq_id, id; |
|
292 |
id uniq_id |
|
293 |
3 1 |
|
294 |
4 2 |
|
295 |
7 3 |
|
296 |
8 4 |
|
297 |
DROP table t1,t2; |
|
298 |
CREATE TABLE `t1` ( |
|
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`) |
|
303 |
) ENGINE=MyISAM; |
|
304 |
CREATE TABLE `t2` ( |
|
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`) |
|
309 |
) ENGINE=MyISAM; |
|
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); |
|
316 |
select t1.* from t1 |
|
317 |
left join t2 using(order_id, product_id, product_type) |
|
318 |
where t2.order_id=NULL; |
|
319 |
order_id product_id product_type |
|
320 |
select t1.* from t1 |
|
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 |
|
326 |
drop table t1,t2; |
|
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; |
|
332 |
id id |
|
333 |
alter table t1 add key id (id); |
|
334 |
select * from t1, t2 where t1.id = t2.id; |
|
335 |
id id |
|
336 |
drop table t1,t2; |
|
337 |
create table t1 ( |
|
338 |
id integer, |
|
339 |
id2 integer not null, |
|
340 |
index (id), |
|
341 |
index (id2) |
|
342 |
);
|
|
343 |
insert into t1 values(null,null),(1,1); |
|
344 |
Warnings: |
|
345 |
Warning 1048 Column 'id2' cannot be null |
|
346 |
select * from t1; |
|
347 |
id id2 |
|
348 |
NULL 0 |
|
349 |
1 1 |
|
350 |
select * from t1 where id <=> null; |
|
351 |
id id2 |
|
352 |
NULL 0 |
|
353 |
select * from t1 where id <=> null or id > 0; |
|
354 |
id id2 |
|
355 |
NULL 0 |
|
356 |
1 1 |
|
357 |
select * from t1 where id is null or id > 0; |
|
358 |
id id2 |
|
359 |
NULL 0 |
|
360 |
1 1 |
|
361 |
select * from t1 where id2 <=> null or id2 > 0; |
|
362 |
id id2 |
|
363 |
1 1 |
|
364 |
select * from t1 where id2 is null or id2 > 0; |
|
365 |
id id2 |
|
366 |
1 1 |
|
367 |
delete from t1 where id <=> NULL; |
|
368 |
select * from t1; |
|
369 |
id id2 |
|
370 |
1 1 |
|
371 |
drop table t1; |
|
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; |
|
404 |
COUNT(*) |
|
405 |
15972
|
|
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 |
|
412 |
FLUSH STATUS ; |
|
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; |
|
415 |
a a b b |
|
416 |
1 1 1 NULL |
|
417 |
2 NULL NULL NULL |
|
418 |
3 3 1 NULL |
|
419 |
4 NULL NULL NULL |
|
420 |
SELECT FOUND_ROWS(); |
|
421 |
FOUND_ROWS() |
|
422 |
4
|
|
423 |
SHOW STATUS LIKE "handler_read%"; |
|
424 |
Variable_name Value |
|
425 |
Handler_read_first 0 |
|
426 |
Handler_read_key 6 |
|
427 |
Handler_read_next 2 |
|
428 |
Handler_read_prev 0 |
|
429 |
Handler_read_rnd 0 |
|
430 |
Handler_read_rnd_next 5 |
|
431 |
DROP TABLE t1,t2,t3,t4; |
|
432 |
CREATE TABLE t1 ( |
|
433 |
a int(11) default NULL, |
|
434 |
b int(11) default NULL, |
|
435 |
KEY a (a,b) |
|
436 |
);
|
|
437 |
INSERT INTO t1 VALUES (0,10),(0,11),(0,12); |
|
438 |
CREATE TABLE t2 ( |
|
439 |
a int(11) default NULL, |
|
440 |
b int(11) default NULL, |
|
441 |
KEY a (a) |
|
442 |
);
|
|
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; |
|
445 |
a b a b |
|
446 |
3 11 0 11 |
|
447 |
3 12 0 12 |
|
448 |
drop table t1, t2; |
|
449 |
End of 5.0 tests |