Mysql精华问答（五）| explain 进行Sql分析

Mysql精华问答（五）| explain 进行Sql分析

{EXPLAIN | DESCRIBE | DESC} tbl_name [col_name | wild]{EXPLAIN | DESCRIBE | DESC} [explain_type] {explainable_stmt | FOR CONNECTION connection_id}explain_type: { EXTENDED | PARTITIONS | FORMAT = format_name}format_name: { TRADITIONAL | JSON}explainable_stmt: { SELECT statement | DELETE statement | INSERT statement | REPLACE statement | UPDATE statement}

explain select * from test1 t1 inner join test1 t2 on t1.id=t2.id

结果：

explain select * from test1 t1 where t1.id = (select id from test1 t2 where t2.id=2);

结果：

explain select t1.* from test1 t1inner join (select max(id) mid from test1 group by id) t2on t1.id=t2.mid

结果：

explain select * from test1;

结果：

explain select * from test1 t1 where t1.id = (select id from test1 t2 where t2.id=2);

结果：

explainselect t1.* from test1 t1inner join (select max(id) mid from test1 group by id) t2on t1.id=t2.mid

结果：

explainselect * from test1unionselect* from test2

结果：

explain select * from test2 where id=1;

结果：

explain select * from test2 t1 inner join test2 t2 on t1.id=t2.id;

结果：

explain select * from test2 where code = '001';

结果：

explain select * from test1 t1 inner join test1 t2 on t1.id=t2.id where t1.code='001';

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