key_diff.result
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:1k
- drop table if exists t1;
- CREATE TABLE t1 (
- a char(5) NOT NULL,
- b char(4) NOT NULL,
- KEY (a),
- KEY (b)
- );
- INSERT INTO t1 VALUES ('A','B'),('b','A'),('C','c'),('D','E'),('a','a');
- select * from t1,t1 as t2;
- a b a b
- A B A B
- b A A B
- C c A B
- D E A B
- a a A B
- A B b A
- b A b A
- C c b A
- D E b A
- a a b A
- A B C c
- b A C c
- C c C c
- D E C c
- a a C c
- A B D E
- b A D E
- C c D E
- D E D E
- a a D E
- A B a a
- b A a a
- C c a a
- D E a a
- a a a a
- explain select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B;
- id select_type table type possible_keys key key_len ref rows Extra
- 1 SIMPLE t1 ALL a NULL NULL NULL 5
- 1 SIMPLE t2 ALL b NULL NULL NULL 4 Using where
- select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B order by binary t1.a,t2.a;
- a b a b
- A B a a
- A B b A
- C c C c
- a a a a
- a a b A
- b A A B
- select * from t1 where a='a';
- a b
- A B
- a a
- drop table t1;