问题
I have created some stored procedures in my database (MySQL) as follows.
Stored Procedure 1
CREATE PROCEDURE sp_Name1(
param1,
param2,
......
)
BEGIN
.....
some code
IF cond THEN
call sp_Name2 //Calling 2nd procedure from here.
Update SomeTable .....
SELECT '1' As Result;
END IF
END
Stored Procedure 2
CREATE PROCEDURE sp_Name2(
param1,
param2,
......
)
BEGIN
.....
some code
IF cond THEN
SELECT '2' As Result;
SELECT '3' As Result;
END IF
END
Now I am calling my first stored procedure as follows:
Call sp_Name1(param1, param2, ... );
Here I am getting 4 result sets in MySQL Workbench. 2 results from sp_Name2, 3rd for the update statement in sp_Name1 and 4th from the select statement, also in sp_Name1. Here I am looking for just the last result set. Sometimes the result sequence appears in the expected order, which means the results may come in like Result 1, Result 2, Result 4, Result 3 (In this case I can not judge which result set is useful to me, because last result set may be changed).
How do I suppress unwanted result sets?
EDIT : I have use case for your better understanding.
CREATE PROCEDURE sp_LoginUser( IN Username varchar(50) , IN password varchar(50) )
BEGIN
IF EXISTS( SELECT 1 FROM Users where name = UserName and Pwd = password)
SET userid = 0;
SET loginid = 0;
SELECT userid INTO userid
FROM users
WHERE name = UserName and Pwd = password;
IF userid > 0 THEN
CALL sp_Login(userid);
SET loginid = LAST_INSERT_ID();
END IF;
//only this result i am expecting.
IF loginid > 0 THEN
SELECT userid as userid, loginid AS loginid;
ELSE
SELECT 0 userid, 0 loginid;
END IF;
END IF;
END
CREATE PROCEDURE sp_Login( IN Userid int )
BEGIN
INSERT Logins ( userid, datetime )
VALUES ( Userid, now() );
SELECT LAST_INSERT_ID() AS loginid;
END
So, Now when my user requesting for login and enter his/her username with password on my login page, then I have call sp_LoginUser() on my server. In many cases I have to call sp_Login() separately.
In above case I can set one parameter (eg. loginid) AS INOUT in sp_Login() procedure, assign LAST_INSERT_ID() to it, remove SELECT statement and retrieve in sp_LoginUser(). But when I need to call sp_Login() separately, i must have to declare some variable in my coding to retrieve value.
回答1:
If you don't want those result sets, don't select them.
回答2:
When you perform a select inside a stored procedure the resultset is returned to the client. http://dev.mysql.com/doc/refman/5.5/en/faqs-stored-procs.html#qandaitem-B-4-1-14
CREATE PROCEDURE sp_LoginUser( IN Username varchar(50) , IN password varchar(50) )
BEGIN
--put the resultset into a variable so it don't return back
DECLARE doesUserExist BOOL;
SELECT EXISTS( SELECT 1 FROM Users where name = UserName and Pwd = password ) INTO doesUserExist;
IF doesUserExist
SET userid = 0;
SET loginid = 0;
SELECT userid INTO userid
FROM users
WHERE name = UserName and Pwd = password;
IF userid > 0 THEN
-- call a function instead of a procedure so you don't need to call last_insert_id again
SET loginid = sp_Login(userid);
END IF;
//only this result i am expecting.
IF loginid > 0 THEN
SELECT userid as userid, loginid AS loginid;
ELSE
SELECT 0 userid, 0 loginid;
END IF;
END IF;
END
-- this is now a function so it can return what you need
CREATE FUNCTION sp_Login(Userid int)
RETURNS INTEGER
BEGIN
INSERT Logins ( userid, datetime )
VALUES ( Userid, now() );
SET loginid = LAST_INSERT_ID();
RETURN loginid;
END
回答3:
Use DO SELECT.. if you don't want to return a result set for a select (http://dev.mysql.com/doc/refman/5.6/en/do.html). However, I don't understand why you run the selects in the first place if you don't want the results.
回答4:
I'm not sure why you are selecting LAST_INSERT_ID() in sp_Login and again in sp_LoginUser?
If you need to return LAST_INSERT_ID() from sp_Login you need to either assign an output variable to it or consider using a scalar function instead.
回答5:
Why the stored procs? You can do it with normal SQL:
SET @previous := LAST_INSERT_ID();
INSERT INTO Logins ( userid, datetime )
SELECT Userid, now()
FROM users
WHERE name = UserName
and Pwd = password;
SELECT *
FROM Logins
WHERE ID = LAST_INSERT_ID()
AND ID != @previous;
If the username/password was correct, your rowset will have the row for the login - you could join it to the user table to also get all the user data too.
If the username/password was incorrect, you'll have an empty rowset.
FYI, LAST_INSERT_ID() returns 0 if there are no previous inserts.
Stored procedures are the least preferred way to implement SQL, particularly because they are the least portable way (there are other good reasons too); if you can implement in plain SQL it's a better option. Although this SQL isn't completely portable, it can be converted reasonably easily as most databases have similar functions and features to mysql's.
回答6:
Return multiple values like
CREATE PROCEDURE `sp_ReturnValue`(
p_Id int(11), -- Input param
OUT r_status1 INT(11) -- output param
OUT r_status2 VARCHAR(11) -- output param
OUT r_status3 INT(11) -- output param
)
BEGIN
SELECT Status FROM tblUsers WHERE tblUsers_ID = p_Id; // use of input param
SET r_status1 = 2; // use of output param
SET r_status2 = "ABCD"; // use of string output param
SET r_status3 = 2; // use of output param
END
And READ Like
CREATE PROCEDURE `sp_ReadReturnValue`()
BEGIN
SELECT @ret_value1 AS ret_value1,
@ret_value2 AS ret_value2,
@ret_value3 AS ret_value3;
END
Parameter in node for Out param
con.query("CALL sp_ReturnValue(?, @ret_value1, @ret_value2, @ret_value3); CALL sp_ReadReturnValue;", [id], (err, rows) => {
console.log("Print return value \n ");
console.log(rows[1][0].ret_value1 "\n");
console.log(rows[1][0].ret_value2 "\n");
console.log(rows[1][0].ret_value3 );
})
来源：https://stackoverflow.com/questions/20629558/mysql-stored-procedure-returning-multiple-record-sets