Question

I got a table with username, usergroup and usertype.

A 0 0
B 0 1
C 1 2
D 2 2

Now i want something like

get all the users where the group is 0 or 1 and type is 2

I use:

SELECT * FROM table WHERE usergroup= 0 OR 1 AND usertype=2 GROUP BY usergroup

I expect it will return the username C, but strangely it returns A,C,D
What am I doing wrong?

Answer 1

_{I’m going to ignore that GROUP BY.}

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SELECT * FROM table WHERE usergroup= 0 OR 1 AND usertype=2

What am I doing wrong?

First, you have precedence issues; your SQL query is equivalent to:

SELECT * FROM table WHERE usergroup = 0 OR (1 AND usertype=2)

Use parentheses to be clear:

SELECT * FROM table WHERE (usergroup = 0 OR 1) AND usertype=2

There’s still a problem, in that boolean operators simply don’t work like this: 0 OR 1 is an expression that evaluates to 1.

You have to repeat the thing you’re comparing against:

SELECT * FROM table WHERE (usergroup = 0 OR usergroup = 1) AND usertype=2

However, this can be shortened thus:

SELECT * FROM table WHERE usergroup IN (0, 1) AND usertype=2