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MySql官方手册学习笔记3—MySql中的存储过程简介_MySQL
- WBOYOriginal
- 2016-06-01 13:39:331239browse
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SELECT INTO
CREATE PROCEDURE sp1 (x VARCHAR(5)) //创建储存过程
BEGIN
DECLARE xname VARCHAR(5) DEFAULT 'bob'; //声明局部变量
DECLARE newname VARCHAR(5);
DECLARE xid INT;
SELECT xname,id INTO newname,xid //将查到的属性值存入变量中
FROM table1 WHERE xname = xname;
SELECT newname;
END;
变量名不能与列名一样，当这个程序被调用的时候，无论table.xname列的值是什么，变量newname将返回值‘bob’。
HANDLER
mysql> CREATE TABLE test.t (s1 int,primary key (s1));
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter // //将定界符“;”改为“//”，因为程序中需要用到“;”。
mysql> CREATE PROCEDURE handlerdemo ()
-> BEGIN
-> DECLARE insertErr CONDITION FOR SQLSTATE '23000'; //声明CONDITION
-> DECLARE CONTINUE HANDLER FOR insertErr SET @x2 = 1;//声明HANDLER
-> SET @x = 1; //为局部变量赋值
-> INSERT INTO test.t VALUES (1);
-> SET @x = 2;
-> INSERT INTO test.t VALUES (1);
-> SET @x = 3;
-> END;
-> //
Query OK, 0 rows affected (0.00 sec)
mysql> CALL handlerdemo()//
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT @x//
+------+
| @x |
+------+
| 3 |
+------+
1 row in set (0.00 sec)
注意到，@x是3，这表明MySQL被执行到程序的末尾。如果DECLARE CONTINUE HANDLER FOR insertErr SET @x2 = 1; 这一行不在，第二个INSERT因PRIMARY KEY强制而失败之后,MySQL可能已经采取 默认(EXIT)路径，并且SELECT @x可能已经返回2。
CURSOR
CREATE PROCEDURE curdemo()
BEGIN
DECLARE done INT DEFAULT 0;
DECLARE a CHAR(16);
DECLARE b,c INT;
DECLARE cur1 CURSOR FOR SELECT id,data FROM test.t1;
DECLARE cur2 CURSOR FOR SELECT i FROM test.t2;
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;
OPEN cur1; //使用前先打开游标
OPEN cur2;
REPEAT
FETCH cur1 INTO a, b;
FETCH cur2 INTO c;
IF NOT done THEN
IF b
INSERT INTO test.t3 VALUES (a,b);
ELSE
INSERT INTO test.t3 VALUES (a,c);
END IF;
END IF;
UNTIL done END REPEAT;
CLOSE cur1;
CLOSE cur2;
END
CASE
CASE case_value
WHEN when_value THEN statement_list
[WHEN when_value THEN statement_list] ...
[ELSE statement_list]
END CASE
Or:
CASE
WHEN search_condition THEN statement_list
[WHEN search_condition THEN statement_list] ...
[ELSE statement_list]
END CASE
存储程序的CASE语句实现一个复杂的条件构造。如果search_condition 求值为真，相应的SQL被执行。如果没有搜索条件匹配，在ELSE子句里的语句被执行。
LEAVE
LEAVE label
这个语句被用来退出任何被标注的流程控制构造。它和BEGIN ... END或循环一起被使用。
ITERATE
ITERATE label
ITERATE只可以出现在LOOP, REPEAT, 和WHILE语句内。ITERATE意思为：“再次循环。”
例如：
CREATE PROCEDURE doiterate(p1 INT)
BEGIN
label1: LOOP
SET p1 = p1 + 1;
IF p1
LEAVE label1;
END LOOP label1;
SET @x = p1;
END
REPEAT
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> CALL dorepeat(1000)//
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT @x//
+------+
| @x |
+------+
| 1001 |
+------+
1 row in set (0.00 sec)
WHILE
CREATE PROCEDURE dowhile()
BEGIN
DECLARE v1 INT DEFAULT 5;
WHILE v1 > 0 DO
...
SET v1 = v1 - 1;
END WHILE;
EN
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