通用合并表存储过程循环变量与字符连接
存储过程循环变量与字符连接
Java代码
mysql> DELIMITER $$
mysql> drop PROCEDURE sp_test_switch$$
Query OK, 0 rows affected (0.01 sec)
mysql> CREATE PROCEDURE sp_test_switch()
-> BEGIN
-> declare a int;
-> declare b varchar(5000);
-> set a=1;
-> set b='';
-> while a<10 do
-> set b = concat(b,',',a);
-> set a=a+1;
-> end while;
-> select b;
-> END
-> $$
Query OK, 0 rows affected (0.00 sec)
mysql> DELIMITER ;
mysql>
mysql> call sp_test_switch();
+--------------------+
| b |
+--------------------+
| ,1,2,3,4,5,6,7,8,9 |
+--------------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql存储过程的变量定义：declare和直接set @var什么区别？
我的理解是, declare定义的是局部变量, 只能用在存储过程或函数中, 其有效区间就是存储过程或函数中声明该变量的begin end区间.而@var属于用户变量(自己声明的), 其有效区间就是该session, 你既可以在存储过程或函数中使用, 也可以在自己写的SQL语句中使用.还有@不需要声明类型，declare必须指定类型
Java代码
CREATE PROCEDURE sp_starnight_cbj()
BEGIN
DECLARE A INT DEFAULT 1;
DECLARE B VARCHAR(5000) DEFAULT '';
WHILE A<10 DO
SET B = CONCAT(B,',',A);
SET A=A+1;
END WHILE;
SELECT B;
END;
应用：所有分表的视图
Java代码
DROP PROCEDURE IF EXISTS `merage_branch_table`;
CREATE PROCEDURE `merage_branch_table`(
IN p_table_name VARCHAR(200),
IN p_branch_size INT,
in p_lpad INT
)
BEGIN
DECLARE m_begin_row INT DEFAULT 0;
SET @m_merage_sql_view = CONCAT('CREATE VIEW ', p_table_name, ' AS ');
WHILE m_begin_row
IF(m_begin_row=p_branch_size-1)
THEN SET @m_merage_sql_view = CONCAT(@m_merage_sql_view, 'SELECT * FROM ', p_table_name, '_', LPAD(m_begin_row, p_lpad, 0));
ELSE SET @m_merage_sql_view = CONCAT(@m_merage_sql_view, 'SELECT * FROM ', p_table_name, '_', LPAD(m_begin_row, p_lpad, 0),' UNION ALL ');
END IF;
SET m_begin_row = m_begin_row+1;
END WHILE;
PREPARE main_stmt FROM @m_merage_sql_view;
EXECUTE main_stmt;
END;
所有分表的视图