每个存储程序都包含一个由 SQL 语句组成的主体。该语句可以是由多个语句通过分号（;）分隔组成的复合语句。例如，下面的存储过程具有由一个 BEGIN ... END 块组成的主体，该块包含一个 SET 语句和一个 REPEAT 循环，循环内部又包含另一个 SET 语句：Each stored program contains a body that consists of an SQL statement. This statement may be a compound statement made up of several statements separated by semicolon (;) characters. For example, the following stored procedure has a body made up of a BEGIN ... END block that contains a SET statement and a REPEAT loop that itself contains another SET statement:

CREATE PROCEDURE dorepeat(p1 INT)
BEGIN
  SET @x = 0;
  REPEAT SET @x = @x + 1; UNTIL @x > p1 END REPEAT;
END;

如果你使用mysql 客户端程序来定义包含分号字符的存储程序，会出现一个问题。默认情况下，mysql 会将分号识别为语句分隔符，因此你必须临时重新定义分隔符，使 mysql 将整个存储程序定义传递给服务器。If you use the mysql client program to define a stored program containing semicolon characters, a problem arises. By default, mysql itself recognizes the semicolon as a statement delimiter, so you must redefine the delimiter temporarily to cause mysql to pass the entire stored program definition to the server.

要重新定义 mysql 分隔符，请使用 delimiter 命令。以下示例展示了如何对刚才显示的 dorepeat() 存储过程执行此操作。分隔符被更改为 //，以便将整个定义作为单条语句传递给服务器，然后在调用存储过程之前恢复为 ;。这使得存储过程体中使用的 ; 分隔符可以传递给服务器，而不会被 mysql 本身解释。To redefine the mysql delimiter, use the delimiter command. The following example shows how to do this for the dorepeat() procedure just shown. The delimiter is changed to // to enable the entire definition to be passed to the server as a single statement, and then restored to ; before invoking the procedure. This enables the ; delimiter used in the procedure body to be passed through to the server rather than being interpreted by mysql itself.

mysql> delimiter //

mysql> CREATE PROCEDURE dorepeat(p1 INT)
    -> BEGIN
    ->   SET @x = 0;
    ->   REPEAT SET @x = @x + 1; UNTIL @x > p1 END REPEAT;
    -> END
    -> //
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;

mysql> CALL dorepeat(1000);
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT @x;
+------+
| @x   |
+------+
| 1001 |
+------+
1 row in set (0.00 sec)

您可以将分隔符重新定义为除 // 以外的字符串，分隔符可以由单个字符或多个字符组成。您应避免使用反斜杠 (\) 字符，因为它是 MySQL 的转义字符。You can redefine the delimiter to a string other than //, and the delimiter can consist of a single character or multiple characters. You should avoid the use of the backslash (\) character because that is the escape character for MySQL.

下面是一个示例函数，该函数接受一个参数，使用 SQL 函数执行操作，并返回结果。在这种情况下，不需要使用 delimiter，因为函数定义中没有内部的 ; 语句分隔符：The following is an example of a function that takes a parameter, performs an operation using an SQL function, and returns the result. In this case, it is unnecessary to use delimiter because the function definition contains no internal ; statement delimiters:

mysql> CREATE FUNCTION hello (s CHAR(20))
mysql> RETURNS CHAR(50) DETERMINISTIC
    -> RETURN CONCAT('Hello, ',s,'!');
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT hello('world');
+----------------+
| hello('world') |
+----------------+
| Hello, world!  |
+----------------+
1 row in set (0.00 sec)