if exists

[xxreenaxx1]

I am trying to run this query on a webpage but I am getting an error. So I tested this on mysql and this is giving me error as well.

 

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IF EXISTS(SELECT * FROM user u, subject s, test t, question q, answer a WHERE u.' at line 1

 

IF EXISTS
(SELECT * FROM user u, subject s, test t, question q, answer a WHERE u.Use_ID = 1
    AND t.Sub_ID = 1
AND s.Sub_ID = t.Sub_ID
AND q.Que_ID = a.Que_ID)

 

am I doing anything wrong.

[Adam]

You cannot use an IF statement in MySQL out of a routine (i.e. stored procedure or function). Also EXISTS is for use on sub-queries. What exactly is it's purpose in being there?

[JustLikeIcarus]

Looks like your trying to use MS-SQL on MySQL.

[xxreenaxx1]

oh..

 

I want to check if the user has already taken a question. This is the reason why I am compairing a.Que_ID = q.Que_ID. So if the person has taken the exam, this will not be displayed.

[Adam]

Well then you should just let the query return 0 rows and check for an empty result set within the application.

[xxreenaxx1]

I dont know how implement that?? :S

[Adam]

Show us the PHP you're using to make the query.

[JustLikeIcarus]

$link = mysql_connect("localhost", "mysql_user", "mysql_password");
mysql_select_db("database", $link);

$result = mysql_query("SELECT * FROM user u, subject s, test t, question q, answer a WHERE u.Use_ID = 1
    AND t.Sub_ID = 1
    AND s.Sub_ID = t.Sub_ID
    AND q.Que_ID = a.Que_ID", $link);

$num_rows = mysql_num_rows($result);

if($num_rows)
{
}
else
{
}