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標題: [SQL與PHP] MYSQL大小寫的約定 [打印本頁]

作者: gswdkimo 時間: 2011-8-22 14:16 標題: MYSQL大小寫的約定

MYSQL在默認的情況下查詢是不區分大小寫的，例如：

mysql> create table t1(
-> name varchar(10));
Query OK, 0 rows affected (0.09 sec)

mysql> insert into t1 values('you'),('You'),('YOU');
Query OK, 3 rows affected (0.05 sec)
Records: 3 Duplicates: 0 Warnings: 0
對這個表，缺省情況下，下面兩個查詢的結果是一樣的：

mysql> select * from t1 where name = 'you';
+------+
| name |
+------+
| you |
| You |
| YOU |
+------+
3 rows in set (0.00 sec)

mysql> select * from t1 where name = 'YOU';
+------+
| name |
+------+
| you |
| You |
| YOU |
+------+
3 rows in set (0.00 sec)

如果想讓MYSQL知道你輸入的字母是大寫還是小寫的，修改表：

mysql> alter table t1 change name name varchar(10) binary;
Query OK, 3 rows affected (0.20 sec)
Records: 3 Duplicates: 0 Warnings: 0

mysql> select * from t1 where name = 'you';
+------+
| name |
+------+
| you |
+------+
1 row in set (0.00 sec)

mysql> select * from t1 where name = 'YOU';
+------+
| name |
+------+
| YOU |
+------+
1 row in set (0.00 sec)

如果你只是想在SQL語句中實現的話：

mysql> select * from t1 where name = binary 'YOU';
+------+
| name |
+------+
| YOU |
+------+
1 row in set (0.02 sec)

mysql> select * from t1 where name = binary 'you';
+------+
| name |
+------+
| you |
+------+
1 row in set (0.00 sec)

如果不想這麼麻煩而想服務一開啟就讓大小寫一致的話：
可以修改my.ini或者my.cnf
[mysqld]
lower_case_table_names=1
（0：區分；1：不區分）
然後重啟MYSQL服務。

mysql> show variables like '%case_table%';
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| lower_case_table_names | 1 |
+------------------------+-------+
1 row in set (0.00 sec)
註：WINDOWS系統不用修改，系統默認就是1
LINUX 系統默認是0。因為LINUX下的腳本都是區分大小寫的。

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