MySQL 触发器、存储过程、游标

程序员文章站 2022-06-04 08:45:42

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MySQL 触发器、函数

触发器有时也称作事件-条件-动作规则，或者ECA规则。

触发器语法

DROP 如果触发器已存在，则删除
delimiter 设置数据库语句的定界符（分隔符）
CREATE TRIGGER创建触发器
指出触发事件并告诉触发器实在触发事件之前还是之后使用数据库状态的子句
FOR EACH ROW 告诉触发器只对每个修改的行执行依次，还是对由SQL语句做的所有修改执行一次的子句
BEGIN 触发器执行部分，OLD表示原来的数据，NEW表示新插入的数据，因此对于SELECT语句可以使用OLD值，对于DELECT使用OLD值，INSERT使用NEW值，UPDATE 使用NEW值和OLD值

DROP TRIGGER IF EXISTS tr_after_delete_distribution_goods;
delimiter //
CREATE TRIGGER tr_after_delete_distribution_goods
AFTER DELETE ON t_distribution_goods FOR EACH ROW
trig:BEGIN
    DECLARE var_warehouseCode SMALLINT;-- 定义变量
    SELECT f_warehouseCode INTO var_warehouseCode FROM t_distribution WHERE f_distNumber=OLD.f_distNumber;
    UPDATE t_stock_total SET f_lockedQuantity=f_lockedQuantity-OLD.f_distQuantity WHERE f_goodsId=OLD.f_goodsId AND f_warehouseCode=var_warehouseCode;

END;
//
delimiter ;

设置触发器条件，当f_flag为“已作废”时执行更新语句

DROP TRIGGER IF EXISTS tr_after_update_distribution;
delimiter //
CREATE TRIGGER tr_after_update_distribution
AFTER UPDATE ON t_distribution FOR EACH ROW
trig:BEGIN
        DECLARE var_goodsId INT;
        DECLARE var_distQuantity INT;
    if (NEW.f_flag='INVALID') then 
        SELECT f_goodsId,f_distQuantity INTO var_goodsId,var_distQuantity FROM t_distribution_goods WHERE f_distNumber=OLD.f_distNumber;
        UPDATE t_stock_total SET f_lockedQuantity=f_lockedQuantity-var_distQuantity WHERE f_goodsId=var_goodsId AND f_warehouseCode=OLD.f_warehouseCode;
    end if;

END;
//
delimiter ;

插入触发器

DROP TRIGGER IF EXISTS tr_after_insert_commodity_stock;
delimiter //
CREATE TRIGGER tr_after_insert_commodity_stock
AFTER INSERT ON t_commodity FOR EACH ROW
trig:BEGIN
    DECLARE var_warehouseCode INT;
    SELECT f_warehouseCode INTO var_warehouseCode FROM t_stock WHERE f_purchaseNumber=NEW.f_purchaseNumber AND f_goodsId=NEW.f_goodsId;
    UPDATE t_stock SET f_inQuantity=f_inQuantity+1 WHERE f_purchaseNumber=NEW.f_purchaseNumber AND f_goodsId=NEW.f_goodsId;
    UPDATE t_stock_total SET f_quantity=f_quantity+1 WHERE f_goodsId=NEW.f_goodsId AND f_warehouseCode=var_warehouseCode;

END;
//
delimiter ;

查看触发器

SELECT TRIGGER_NAME  FROM information_schema.`TRIGGERS`;

触发器详细代码

SHOW CREATE TRIGGER tr_after_update_stock;

推荐参考链接：http://www.cnblogs.com/fengxw/p/6076150.html

MySQL 存储过程

-- 生成一个RFID
-- 参数var_goodsId,var_quantity

DROP PROCEDURE IF EXISTS p_next_sheet_rfid;
delimiter //
CREATE PROCEDURE p_next_sheet_rfid (
    OUT var_return      VARCHAR(30),-- 输出值
    IN  var_goodsId    INT,-- 输入值
    IN  var_quantity   INT
    )
BEGIN
    DECLARE var_category SMALLINT;-- 临时变量
    DECLARE var_brand INT;
    DECLARE var_goods INT;
    DECLARE var_maxRfid INT;
    DECLARE var_str VARCHAR(20) DEFAULT ''; 

    -- 异常时回滚跳出
    -- DECLARE EXIT HANDLER FOR SQLEXCEPTION ROLLBACK;

    SET var_return='0';
    START TRANSACTION;
    -- 临时变量赋值
    SELECT f_id,f_categoryCode,f_brandCode,f_lastRfidNumber INTO var_goods, var_category, var_brand, var_maxRfid FROM t_goods WHERE f_id=var_goodsId;

    SET var_maxRfid = var_maxRfid % 100000000;
    UPDATE t_goods SET f_lastRfidNumber=var_maxRfid+var_quantity WHERE f_id=var_goodsId;
    -- concat连接各参数，LPAD(str,len,padstr)用字符串 padstr对 str进行左边填补直至它的长度达到 len个字符长度，然后返回 str。如果 str的长度长于 len'，那么它将被截除到 len个字符。RPAD(str,len,padstr)为右边
    SELECT CONCAT(LPAD(var_category, 3, '0'), LPAD(var_brand, 4, '0'), LPAD(var_goods, 5, '0'), LPAD(var_maxRfid+1, 8, '0')) INTO var_str;
    SET var_return = RIGHT(var_str, 20);

    COMMIT;
END;
//
delimetr;

存储过程，使用游标循环遍历数据表修改另一张表

-- 逐条从t_goods_temp导入货品到t_goods.
DROP procedure IF EXISTS p_import_goods_from_temp;
delimiter //
CREATE PROCEDURE p_import_goods_from_temp ()
BEGIN
    DECLARE var_categoryCode SMALLINT;
    DECLARE var_name VARCHAR(120);
    DECLARE var_brandCode SMALLINT;
    -- DECLARE var_brandName VARCHAR(18);
    DECLARE var_superCategoryName VARCHAR(18);
    DECLARE var_categoryName VARCHAR(18);
    DECLARE var_saleSpec VARCHAR(18); 
    DECLARE var_unitCode SMALLINT;
    -- DECLARE var_unitName VARCHAR(12);
    DECLARE var_marketPrice DECIMAL(6, 2);
    DECLARE var_done INT DEFAULT 0;
    DECLARE var_warning INT DEFAULT 0; 

    DECLARE cur_goods_temp CURSOR FOR -- 定义游标，设置结果集
        SELECT f_name, f_brandCode, f_superCategoryName, f_categoryName, f_saleSpec, f_unitCode, f_marketPrice
        FROM v_goods_temp;

    -- 声明异常处理
    DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET var_done = 1; -- 若没有数据返回,程序继续,并将变量var_done设为1 类似于DECLARE CONTINUE HANDLER FOR NOT FOUNDSET var_done = 1;
    DECLARE CONTINUE HANDLER FOR SQLWARNING SET var_warning = 1;
    DECLARE EXIT HANDLER FOR SQLEXCEPTION ROLLBACK;
    START TRANSACTION;-- 开启事务

    SET var_done = 0;
    OPEN cur_goods_temp;  -- 打开游标
    REPEAT-- 开始循环
        FETCH cur_goods_temp INTO var_name, var_brandCode, var_superCategoryName, var_categoryName, var_saleSpec, var_unitCode, var_marketPrice;
        -- SELECT f_categoryCode, var_brandCode, var_unitCode, var_name, var_saleSpec, var_marketPrice, now(), var_done
        --        FROM v_category WHERE f_superCategoryName=var_superCategoryName AND f_categoryName=var_categoryName LIMIT 1;
        -- SELECT 'cur_goods_return_out var_done: ', var_done;
        IF NOT var_done THEN -- var_done=0,异常标识
            INSERT INTO t_goods (f_categoryCode, f_brandCode, f_unitCode, f_name, f_saleSpec, f_marketPrice, f_creationTime)
                SELECT f_categoryCode, var_brandCode, var_unitCode, var_name, var_saleSpec, var_marketPrice, now()
                FROM v_category WHERE f_superCategoryName=var_superCategoryName AND f_categoryName=var_categoryName LIMIT 1;

            IF var_warning THEN
                SHOW warnings;
                CALL p_debug(CONCAT('warning for ', var_categoryName), false);
            END IF;
        END IF;
    UNTIL var_done END REPEAT; -- 出错时退出循环
    CLOSE cur_goods_temp; -- 关闭游标

    COMMIT; -- 提交数据
END;
//
delimiter ;

添加判断条件的，在游标定义语句之前不能使用SELECT定义变量，if条件判断使用=，而不是==

DROP procedure IF EXISTS p_update_distribution_stock;
delimiter //
CREATE PROCEDURE p_update_distribution_stock(
        IN  var_distNumber  INT,
        IN  var_flag     VARCHAR(10)
)
trig:BEGIN
        DECLARE var_goodsId INT;
        DECLARE var_distQuantity INT;
        DECLARE var_done INT DEFAULT 0;
    DECLARE var_warning INT DEFAULT 0; 
        DECLARE var_warehouseCode INT;


        DECLARE cur_disribution CURSOR FOR
            SELECT f_goodsId,f_distQuantity FROM t_distribution_goods WHERE f_distNumber=var_distNumber;

    DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET var_done = 1;
    DECLARE CONTINUE HANDLER FOR SQLWARNING SET var_warning = 1;
    DECLARE EXIT HANDLER FOR SQLEXCEPTION ROLLBACK;
    START TRANSACTION;

    SET var_done = 0;
    OPEN cur_disribution; 
    REPEAT
        FETCH cur_disribution INTO var_goodsId,var_distQuantity;
        IF NOT var_done THEN
            IF (var_flag = 'INVALID') THEN
                SELECT f_warehouseCode INTO var_warehouseCode FROM t_distribution WHERE f_distNumber=var_distNumber;
                UPDATE t_stock_total SET f_lockedQuantity=f_lockedQuantity-var_distQuantity WHERE f_goodsId=var_goodsId AND f_warehouseCode=var_warehouseCode;

            ELSEIF (var_flag = 'CLEAR') THEN
                    SELECT f_warehouseCode INTO var_warehouseCode FROM t_distribution WHERE f_distNumber=var_distNumber;
                UPDATE t_stock_total SET f_lockedQuantity=f_lockedQuantity+var_distQuantity WHERE f_goodsId=var_goodsId AND f_warehouseCode=var_warehouseCode;

            ELSEIF var_warning THEN
                SHOW warnings;
                CALL p_debug(CONCAT('warning for ', var_goodsId), false);
            END IF;
        END IF;
    UNTIL var_done END REPEAT;
    CLOSE cur_disribution;

    COMMIT;
END;
//
delimiter ;

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