If Exists, Then Select Else Insert and Then Select

Select if exist else insert?

Your statement is fine as it is. Only problem is, you can't use it like a normal query. Control structures like IF or WHILE are only allowed in stored procedures or functions.

Just create a procedure like this:

delimiter $$

create procedure select_or_insert()
begin

IF EXISTS (select * from users where username = 'something') THEN
    select id from users where username = 'something';
ELSE 
    insert into users (username) values ('something');
END IF;

end $$

and call it like this:

call select_or_insert();

That's it.

UPDATE if exists else INSERT in SQL

The below query will fulfill your requirement.

INSERT INTO `ALLOWANCE` (`EmployeeID`, `Year`, `Month`, `OverTime`,`Medical`,
`Lunch`, `Bonus`, `Allowance`) values (10000001, 2014, 4, 10.00, 10.00,
10.45, 10.10, 40.55) ON DUPLICATE KEY UPDATE `EmployeeID` = 10000001

if exists update else insert mysql

You can use Store Procedures to solve this problem like below

    DELIMITER $$
    DROP PROCEDURE IF EXISTS `select_or_insert`$$
    CREATE PROCEDURE select_or_insert()
    begin

    IF EXISTS (SELECT * FROM test WHERE id="id") THEN
       SELECT * FROM test WHERE id="id";
    ELSE
       INSERT INTO test (id,name) VALUES ("id",'name');
    END if;

    END$$

   DELIMITER ;

and call it like this:

call select_or_insert();

SQL Server IF EXISTS THEN 1 ELSE 2

If you want to do it this way then this is the syntax you're after;

IF EXISTS (SELECT * FROM tblGLUserAccess WHERE GLUserName ='xxxxxxxx') 
BEGIN
   SELECT 1 
END
ELSE
BEGIN
    SELECT 2
END

You don't strictly need the BEGIN..END statements but it's probably best to get into that habit from the beginning.

SQL - IF EXISTS UPDATE ELSE INSERT INTO

1. Create a UNIQUE constraint on your subs_email column, if one does not already exist:

   ALTER TABLE subs ADD UNIQUE (subs_email)
   

2. Use INSERT ... ON DUPLICATE KEY UPDATE:

   INSERT INTO subs
     (subs_name, subs_email, subs_birthday)
   VALUES
     (?, ?, ?)
   ON DUPLICATE KEY UPDATE
     subs_name     = VALUES(subs_name),
     subs_birthday = VALUES(subs_birthday)
   

You can use the VALUES(col_name) function in the UPDATE clause to
refer to column values from the INSERT portion of the INSERT ... ON
DUPLICATE KEY UPDATE - dev.mysql.com

3. Note that I have used parameter placeholders in the place of string literals, as one really should be using parameterised statements to defend against SQL injection attacks.

---

Related Topics