????????????????????

mysql> EXPLAIN SELECT * FROM test.`friends` WHERE fuid=’364′ and fname=’test5′;
+—-+————-+———+——+—————+————+———+————-+——+————-+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+—-+————-+———+——+—————+————+———+————-+——+————-+
| 1 | SIMPLE | friends | ref | fuid_fname | fuid_fname | 112 | const??const | 2 | Using where
+—-+————-+———+——+—————+————+———+————-+——+————-+

????Sql????????SELECT * FROM test.`friends` WHEREfname=’test5′ and fuid=’364′;???????????????Ч?????????ELECT * FROM test.`friends` WHERE fuid=’364′ and fname=’test5′????????????;

mysql> EXPLAIN SELECT * FROM test.`friends` WHERE fname=’test5′ and fuid=’364′;
+—-+————-+———+——+—————+————+———+————-+——+————-+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+—-+————-+———+——+—————+————+———+————-+——+————-+
| 1 | SIMPLE | friends | ref | fuid_fname | fuid_fname | 112 | const??const | 2 | Using where
+—-+————-+———+——+—————+————+———+————-+——+————-+

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??????÷???????select????????explain???????

mysql> explain select * from test.index_test where time1=’20130517100552′;
+—-+————-+————+——+—————+——-+———+——-+——+————-+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+—-+————-+————+——+—————+——-+———+——-+——+————-+
| 1 | SIMPLE | index_test | ref | time1 | time1 | 253 | const | 1 | Using where |
+—-+————-+————+——+—————+——-+———+——-+——+————-+

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