Mysql 使用“if”和“else”存储过程
我在尝试创建此存储过程时遇到一些困难,欢迎提供任何帮助:Mysql 使用“if”和“else”存储过程,mysql,database,stored-procedures,if-statement,Mysql,Database,Stored Procedures,If Statement,我在尝试创建此存储过程时遇到一些困难,欢迎提供任何帮助: create procedure checando(in nombrecillo varchar(30), in contrilla varchar(30), out resultado int) begin if exists (select * from compas where nombre = nombrecillo and contrasenia = contrilla) then set resultado =
create procedure checando(in nombrecillo varchar(30), in contrilla varchar(30), out resultado int)
begin
if exists (select * from compas where nombre = nombrecillo and contrasenia = contrilla) then
set resultado = 0;
else if exists (select * from compas where nombre = nombrecillo) then
set resultado = -1;
else
set resultado = -2;
end if;
end;
我正在处理的表格是:
+-------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------+-------------+------+-----+---------+-------+
| Nombre | varchar(30) | YES | | NULL | |
| contrasenia | varchar(30) | YES | | NULL | |
+-------------+-------------+------+-----+---------+-------+
问题是您要么没有关闭if,要么需要一个elseif:
我认为这个结构:如果存在选择。。。特定于MS SQL。在MySQL中,EXISTS谓词告诉您子查询是否找到任何行,它的用法如下:从t1中选择column1,其中EXISTS从t2中选择* 您可以像这样重写上述代码行:
DELIMITER $$
CREATE PROCEDURE `checando`(in nombrecillo varchar(30), in contrilla varchar(30), out resultado int)
BEGIN
DECLARE count_prim INT;
DECLARE count_sec INT;
SELECT COUNT(*) INTO count_prim FROM compas WHERE nombre = nombrecillo AND contrasenia = contrilla;
SELECT COUNT(*) INTO count_sec FROM FROM compas WHERE nombre = nombrecillo;
if (count_prim > 0) then
set resultado = 0;
elseif (count_sec > 0) then
set resultado = -1;
else
set resultado = -2;
end if;
SELECT resultado;
END
您可以在如下情况下使用CASE,以实现IF-ELSE
p、 s:以防万一有人需要这样做 @Bohemian说你可以用elif。我想知道在MySQL中哪里可以找到更多关于elif结构的信息。Bash?+1 por los nombrecillos
DELIMITER $$
CREATE PROCEDURE `checando`(in nombrecillo varchar(30), in contrilla varchar(30), out resultado int)
BEGIN
DECLARE count_prim INT;
DECLARE count_sec INT;
SELECT COUNT(*) INTO count_prim FROM compas WHERE nombre = nombrecillo AND contrasenia = contrilla;
SELECT COUNT(*) INTO count_sec FROM FROM compas WHERE nombre = nombrecillo;
if (count_prim > 0) then
set resultado = 0;
elseif (count_sec > 0) then
set resultado = -1;
else
set resultado = -2;
end if;
SELECT resultado;
END
SELECT FROM A a
LEFT JOIN B b
ON a.col1 = b.col1
AND (CASE
WHEN a.col2 like '0%' then TRIM(LEADING '0' FROM a.col2)
ELSE substring(a.col2,1,2)
END
)=b.col2;