mysql 创建函数
CREATE FUNCTION `GetCustomer_A_Realpay`(id varchar(100), begindate datetime, enddate datetime) RETURNS double BEGIN
-- 定义一个变量 fTime,类型为 VARCHAR,长度是255,
-- 默认值为空即'',不是NULL,为空和NULL不一样
declare sumrealpay DOUBLE;
SELECT IFNULL(sum(realpay),0) into sumrealpay from( select DISTINCT b1.id,b1.realpay from gd_orderbill b1 LEFT JOIN gd_orders b on FIND_IN_SET(b.id,b1.orderdid)>0 WHERE b.customerid=id AND b.orderdate BETWEEN begindate AND enddate ) as realpaytb;
RETURN sumrealpay;
END
1. 赋值使用select into ;
2. RETURN 前一行 使用 分号 ; 标识语句结束