MySQL中prepare与execute以及deallocate预处理语句的使用教程-木庄网络博客

本文摘自PHP中文网，作者黄舟，侵删。

这篇文章主要介绍了MySQL中预处理语句prepare、execute与deallocate的使用教程,需要的朋友可以参考下

MySQL官方将prepare、execute、deallocate统称为PREPARE STATEMENT。
我习惯称其为【预处理语句】。

其用法十分简单，

PREPARE stmt_name FROM preparable_stmt
EXECUTE stmt_name
  [USING @var_name [, @var_name] ...]  -
{DEALLOCATE | DROP} PREPARE stmt_name

举个栗子：

mysql> PREPARE pr1 FROM 'SELECT ?+?';
Query OK, 0 rows affected (0.01 sec)
Statement prepared
mysql> SET @a=1, @b=10 ;
Query OK, 0 rows affected (0.00 sec)
mysql> EXECUTE pr1 USING @a, @b;
+------+
| ?+? |
+------+
| 11  |
+------+
1 row in set (0.00 sec)
 
mysql> EXECUTE pr1 USING 1, 2;  -- 只能使用用户变量传递。
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the 
right syntax to use near '1, 2' at line 1
mysql> DEALLOCATE PREPARE pr1;
Query OK, 0 rows affected (0.00 sec)

使用PAREPARE STATEMENT可以减少每次执行SQL的语法分析，
比如用于执行带有WHERE条件的SELECT和DELETE，或者UPDATE，或者INSERT，只需要每次修改变量值即可。
同样可以防止SQL注入，参数值可以包含转义符和定界符。

适用在应用程序中，或者SQL脚本中均可。

更多用法：

同样PREPARE ... FROM可以直接接用户变量：

mysql> CREATE TABLE a (a int);
Query OK, 0 rows affected (0.26 sec)
mysql> INSERT INTO a SELECT 1;
Query OK, 1 row affected (0.04 sec)
Records: 1 Duplicates: 0 Warnings: 0
 
mysql> INSERT INTO a SELECT 2;
Query OK, 1 row affected (0.04 sec)
Records: 1 Duplicates: 0 Warnings: 0
mysql> INSERT INTO a SELECT 3;
Query OK, 1 row affected (0.04 sec)
Records: 1 Duplicates: 0 Warnings: 0
 
mysql> SET @select_test = CONCAT('SELECT * FROM ', @table_name);
Query OK, 0 rows affected (0.00 sec)
 
mysql> SET @table_name = 'a';
Query OK, 0 rows affected (0.00 sec)
mysql> PREPARE pr2 FROM @select_test;
Query OK, 0 rows affected (0.00 sec)
Statement prepared
 
mysql> EXECUTE pr2 ;
+------+
| a  |
+------+
| 1  |
| 2  |
| 3  |
+------+
3 rows in set (0.00 sec)
 
mysql> DROP PREPARE pr2;  -- 此处DROP可以替代DEALLOCATE
Query OK, 0 rows affected (0.00 sec)