mysql extra index_mysql explain中extra的Using where/Using index/Using index condition
表结构CREATETABLE`test`(`i1`int(11)NOTNULLDEFAULT'0',`i2`int(11)NOTNULLDEFAULT'0',`d`dateDEFAULTNULL,`f`int(11)DEFAULT'0',PRIMARYKEY(`i1`,`i2`),KEY`IX_TEST_N1`(`d`))ENGINE=InnoDBDEFAULTCHARSET=utf8;INSER