MySql存储过程

MySQL 存储过程

```sql
	CREATE PROCEDURE myprocedure
	(IN para01 INTEGER)
	BEGIN
		DECLARE var01 CHAR(10);
		IF para01 = 17 THEN
			SET var01 = 'birds';
		ELSE
			SET var01 = 'beasts';
		END IF;
		INSERT INTO table1 VALUES(var01);
	END
```

创建实例

```sql
	CREATE PROCEDURE p1			/*声明存储过程*/
	() 							/*参数列表*/
	SELECT * FROM table_t;		/*主体*/
```

调用存储过程

```sql
	CALL proc01();
```

特征子句

```sql
	CREATE PROCEDURE p2
	()
	LANGUAGE SQL								/*系统默认的，说明主体使用sql语句*/
	NOT DETERMINISTIC
	SQL SECURITY DEFINER
	COMMENT 'AN EXAMPLE PROCEDURE'
	SELECT CURRENT_DATE, RAND() FROM table_t;
```

特征子句反映存储过程的特性，在括号之后，主体之前。

参数

```sql
	CREATE PROCEDURE proc
	()
	...
```

括号里面用于存放参数列表通过IN(入参),OUT(返回值),INOUT(入参和出参相同)

声明变量

```sql
	CREATE PROCEDURE p8
	()
	BEGIN
		DECLARE a INTEGER;
		DECLARE b INTEGER;
		SET a = 5;
		SET b = 6;
		INSERT INTO table1 VALUES(a);
		SELECT s1*a FROM table1 WHERE s1 >= b;
	END;
```

指定默认值

```sql
	CREATE PROCEDURE p8
	()
	BEGIN
		DECLARE a INTEGER DEFAULT 5;
		DECLARE b INTEGER DEFAULT 5;
		INSERT INTO table1 VALUES(a);
		SELECT s1*a FROM table1 WHERE s1 >= b;
	END;
```

作用域

```sql
	CREATE PROCEDURE p8
	()
	BEGIN
		DECLARE x1 CHAR(5) DEFAULT 'outer';
		BEGIN
			DECLARE x1 CHAR(5) DEFAULT 'inner';
			SELECT x1;
		END;
	END;
```

条件表达式

```sql
	CREATE PROCEDURE p12
	(IN para01 INTEGER)
	BEGIN
		DECLARE var01 INTEGER;
		SET var01 = para01+1;
		IF var01 = 0 THEN
			INSERT INTO table1 VALUES(17);
		END IF;
		IF para01 = 0 THEN
			UPDATE table1 SET s1 = s1+1;
		ELSE
			UPDATE table1 SET s1 = s1 +2;
		END IF;
	END;
```

CASE 指令

```sql
	CREATE PROCEDURE p12
	(IN para01 INTEGER)
	BEGIN
		DECLARE var01 INTEGER;
		SET var01 = para01 + 1;
		CASE var01
			WHEN 0 THEN INSERT INTO table1 VALUES(12);
			WHEN 1 THEN INSERT INTO table1 VALUES(90);
			ELSE INSERT INTO table1 VALUES(80);
		END CASE;
	END;
```

循环

一种是类似编程语言中的while循环，另一种是do...while循环，还有一种是loop

```sql
	CREATE PROCEDURE p12
	()
	BEGIN
		DECLARE var01 INTEGER;
		SET var01 = 0;
		WHILE var01 < 5 DO
			INSERT INTO table1 VALUES(var01);
			SET var01 = var01 +1;
		END WHILE;
	END;
```

```sql
	CREATE PROCEDURE p23
	()
	BEGIN
		DECLARE var01 INTEGER;
		SET var01 = 0;
		REPEAT
			INSERT INTO table1 VALUES(12);
			SET var01 = var01 + 1;
			UNTIL var01 >=5；
		END REPEAT;
	END;
```

LEAVE 类似break

sql CREATE PROCEDURE p123 () BEGIN DECLARE var01 INTEGER; SET var01 = 0; myloop: LOOP INSERT INTO table1 VALUES(var01); SET var01 = var01 + 1; IF var01 >= 5 THEN LEAVE myloop; END IF; END LOOP; END;

ITERATE 类似循环中使用的continue

sql CREATE PROCEDURE p123 () BEGIN DECLARE var01 INTEGER; SET var01 = 0; myloop: LOOP INSERT INTO table1 VALUES(var01); SET var01 = var01 + 1; IF var01 >= 5 THEN ITERATE myloop; END IF; END LOOP; END;

标签

标签增加可读性

```sql
	CREATE PROCEDURE p34
	()
	label_01: BEGIN
		label_02: WHILE 0 =1 DO
			LEAVE label_02;
		END WHILE label_02;
	END label_01;
```

异常处理

```sql
	CREATE PROCEDURE p22
	(IN para01 INTEGER)
	BEGIN
		DECLARE EXIT HANDLER FOR 1215					/*声明异常处理器*/
			INSERT INTO error_log VALUES(error_msg);
		INSERT INTO table1 VALUES(para01);
	END;
```

异常声明语法：
DECLARE
{EXIT|CONTINUE} //退出还是继续
HANDLER FOR
{error-number|{SQLSTATE error-string}|condition} //异常的原因
SQL statement //捕获异常后执行的sql语句

```sql
	CREATE PROCEDURE p34
	()
	BEGIN
		DECLARE CONTINUE HANDLER
		FOR SQLSTATE '23000'
		SELECT * FROM table1;  /*当出现23000的错误后，会自动执行改行*/

		sql...

	END;
```

condition 声明，就是给异常处理器命名

```sql
	CREATE PROCEDURE p45
	()
	BEGIN
		DECLARE 'Constraint Violation'
			CONDITION FOR SQLSTATE '23000';
		DECLARE EXIT HANDLER FOR
			'Constraint Violation'
			ROLLBACK;
		START TRANSACTION;
		INSERT INTO table1 VALUES(1);
		COMMENT;
	END;
```

游标

```sql
	CREATE PROCEDURE p25
	(OUT returnval INTEGER)
	BEGIN
		DECLARE a,b INTEGER;
		DECLARE cur01 CURSOR FOR
			SELECT s1 FROM table1;
		DECLARE CONTINUE HANDLER FOR
			NOT FOUND
			SET b = 1;
		OPEN cur01;
		REPEAT
			FETCH cur01 INTO a;
			UNTIL b = 1;
		END REPEAT;
		CLOSE cur01;
		SET returnval = a;
	END;
```

声明顺序：先声明普通变量，然后声明游标，最后声明异常处理器。

游标的特性

在mysql5.0 中，游标是只读的，而且只能顺序读取，也不能执行更新操作。

函数

```sql
	CREATE FUNCTION	 factorial
		(n DECIMAL(3,0))
		DETERMINISTIC
		BEGIN
			DECLARE factorial DECIMAL(20,0) DEFAULT 1;
			DECLARE counter DECIMAL(3,0);
			SET counter = n;
			factorial_loop: REPEAT
				SET factorial = factorial * counter;
				SET counter = counter + 1;
			UNTIL counter =1
			END REPEAT;
		RETURN factorial;
		END;
```