Error using IF statement in MySQL

Question

I'm trying to create a mySQL Script file, so i can easily execute my changes in differente databases, but I'm having problems with a IF statement. (I'm using MySQL Workbench).

CREATE TABLE IF NOT EXISTS `build` (
    `ID` int(11) NOT NULL AUTO_INCREMENT,
    `Version` varchar(20) NOT NULL,
    `Date` datetime DEFAULT NULL,  
    PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

IF EXISTS(select 1 from build where Versao = '1.1') THEN select "yes";

The create table sentence is executed correctly, but the "IF Exists(select..." statement is giving the following error:

SYNTAX ERROR: IF (if) is not a valid input at this position

The select "Yes" command will actually be replaced by an insert command. I'm just trying to test if the IF command will work.

I've also tried to put the IF EXISTS(select line in a separated query, but had the same result.

What am I doing wrong?

Tim Biegeleisen · Accepted Answer · 2016-06-20 15:49:21Z

1

The SQL IF function as I imagine you want to use should be used inside a function, which you never declared.

If you want a standalone query which will behave the way you expect, then you can try this:

SELECT CASE WHEN EXISTS (SELECT 1 FROM build WHERE Versao = '1.1')
            THEN "yes"
            ELSE "no"
       END
LIMIT 1

answered Jun 20, 2016 at 15:49

Tim Biegeleisen

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Comments

Zach Victor · Accepted Answer · 2016-08-19 05:36:04Z

0

SQL functions can only be used inside a statement or inside a stored procedure/routine.

This SELECT statement should work for you:

SELECT IF(EXISTS(SELECT 1 FROM build WHERE Versao = '1.1'), 'yes', 'no') AS test;

answered Aug 19, 2016 at 5:36

Zach Victor

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2 Comments

Marlon Over a year ago

The problem is that i don't want to return yes or no. It was just a test. what i want is to execute one or more commands depending on the table existing.

Zach Victor Over a year ago

OK. Could you please give an example of the commands you'd like to execute conditionally? Are they in SQL?

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