select * from qs_exam_info where TRANS_DATE LIKE '2018-08-18%'select * from qs_exam_info where date(TRANS_DATE) = '20180818'數據庫里面TRANS_DATE是按2018-10-16 00:14:17這樣的格式存儲的
2 回答
繁星coding
TA貢獻1797條經驗 獲得超4個贊
如果 TRANS_DATE 為 varchar/char 類型，且該字段有索引，那么大部分情況下第一句比第二句更快
如果 TRANS_DATE 為 timestamp/datetime 類型，兩句都用不到索引，全表掃描，所以效率差不多
躍然一笑
TA貢獻1826條經驗 獲得超6個贊
mysql> select count(*) from table where date like '2018-08-18%';
+----------+
| count(*) |
+----------+
| 2128 |
+----------+
1 row in set (0.98 sec)
mysql> select count(*) from table where date(date) = '2018-08-18';
+----------+
| count(*) |
+----------+
| 2128 |
+----------+
1 row in set (1.21 sec)
mysql> select count(*) from table where date(date) = '2018-08-18';
+----------+
| count(*) |
+----------+
| 2128 |
+----------+
1 row in set (1.21 sec)
mysql> select count(*) from table where date like '2018-08-18%';
+----------+
| count(*) |
+----------+
| 2128 |
+----------+
1 row in set (0.98 sec)
mysql> select count(*) from table;
+----------+
| count(*) |
+----------+
| 2066946 |
+----------+
1 row in set (0.66 sec)
mysql>
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