mysql´æ´¢¹ý³ÌÓï·¨

±äÁ¿¶¨Òå:
DECLARE variable_name [,variable_name...] datatype [DEFAULT value];
ÆäÖУ¬datatypeΪmysqlµÄÊý¾ÝÀàÐÍ£¬Èç:INT, FLOAT, DATE, VARCHAR(length)
Àý:
DECLARE l_int INT unsigned default 4000000; DECLARE l_numeric NUMERIC(8,2) DEFAULT 9.95; DECLARE l_date DATE DEFAULT '1999-12-31'; DECLARE l_datetime DATETIME DEFAULT '1999-12-31 23:59:59'; DECLARE l_varchar VARCHAR(255) DEFAULT 'This will not be padded'; 
±äÁ¿¸³Öµ
SET ±äÁ¿Ãû = ±í´ïʽֵ [,variable_name = expression ...]
 
²ÎÊý
mysql´æ´¢¹ý³ÌµÄ²ÎÊýÓÃÔÚ´æ´¢¹ý³ÌµÄ¶¨Ò壬¹²ÓÐÈýÖÖ²ÎÊýÀàÐÍ,IN,OUT,INOUT
Create procedure|function([[IN |OUT |INOUT ] ²ÎÊýÃû Êý¾ÝÀàÐÎ...])
 
IN ÊäÈë²ÎÊý
±íʾ¸Ã²ÎÊýµÄÖµ±ØÐëÔÚµ÷Óô洢¹ý³Ìʱָ¶¨£¬ÔÚ´æ´¢¹ý³ÌÖÐÐ޸ĸòÎÊýµÄÖµ²»Äܱ»·µ»Ø£¬ÎªÄ¬ÈÏÖµ
OUT Êä³ö²ÎÊý
¸ÃÖµ¿ÉÔÚ´æ´¢¹ý³ÌÄÚ²¿±»¸Ä±ä£¬²¢¿É·µ»Ø
INOUT ÊäÈëÊä³ö²ÎÊý
µ÷ÓÃʱָ¶¨£¬²¢Çҿɱ»¸Ä±äºÍ·µ»Ø
IN²ÎÊýÀý×Ó:
´´½¨
mysql> CREATE PROCEDURE sp_demo_in_parameter(IN p_in INT) BEGIN SELECT p_in; /*²éѯÊäÈë²ÎÊý*/*/ SET p_in=2; /*ÐÞ¸Ä*/ select p_in;/*²é¿´Ð޸ĺóµÄÖµ*/ END;
Ö´Ðнá¹û:
mysql> set @p_in=1
mysql> call sp_demo_in_parameter(@p_in)
+------+
| p_in |
+------+
|    1 |
+------+
 
+------+
| p_in |
+------+
|    2 |
+------+
 
mysql> select @p_in;
 
+-------+
| @p_in |
+-------+
| 1     |
+-------+
 
ÒÔÉÏ¿ÉÒÔ¿´³ö£¬p_inËäÈ»ÔÚ´æ´¢¹ý³ÌÖб»Ð޸ģ¬µ«²¢²»Ó°Ïì@p_idµÄÖµ
OUT²ÎÊýÀý×Ó
´´½¨:
mysql> CREATE PROCEDURE sp_demo_out_parameter(OUT p_out INT) BEGIN SELECT p_out;/*²é¿´Êä³ö²ÎÊý*/ SET p_out=2;/*Ð޸IJÎÊýÖµ*/ SELECT p_out;/*¿´¿´Óзñ±ä»¯*/ END;
Ö´Ðнá¹û:
mysql> SET @p_out=1
mysql> CALL sp_demo_out_parameter(@p_out)
+-------+
| p_out |
+-------+
|  NULL |
+-------+
/*δ±»¶¨Ò壬·µ»ØNULL*/
+-------+
| p_out |
+-------+
|     2 |
+-------+
 
mysql> SELECT @p_out;
+-------+
| p_out |
+-------+
|     2 |
+----------+
INOUT²ÎÊýÀý×Ó:
mysql>