Reusing the same value in a SQL query

Question

I am trying to use the same value from a SELECT statement multiple times.
The beginning of my query looks like this:

IF EXISTS (SELECT * FROM `friends` WHERE (`Friend1ID`=value OR `Friend2ID`=value))...

value should be the result of a SELECT query, say:

SELECT `ID` FROM `users` WHERE `name`='daniel'

I could use the same SELECT statement twice, but are there any other possibilities that would make the query "cleaner"?

Ross Bush · Accepted Answer · 2016-06-02 19:58:07Z

2

If you are simply trying to get a list of friends with an associated user name of 'daniel' then you can use an INNER JOIN.

SELECT 
    * 
FROM  
    friends
    INNER JOIN users ON users.ID=friends.friends1ID OR users.ID=friends.friends2ID

WHERE
    users.name='daniel'

answered Jun 2, 2016 at 19:35

Ross Bush

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