SELECT statement issue with OR

Question

I am trying to do a filter query by using the next statement:

SELECT * FROM user_jobs,users WHERE user_jobs.job_title LIKE "%some_keyword%" **OR** user_jobs.job_title LIKE "%another_keyword%" AND user.id=user_jobs.userid

Specs: users.id is PK and user_jobs.userid is FK to users.id

I am trying to filter the users to get the ones that have similar values as specified. When I run it I get a very long loop and finally a large list of users that contains duplicates. (eg I only have 300 users and the query shows over 3000 results)

What am I doing wrong, please?

Thanks in advance!

Answer 1

AND takes precedence over OR ; use parentheses to achieve the desired result.

SELECT * FROM user_jobs, users
WHERE
    (user_jobs.job_title LIKE "%some_keyword%"
  OR user_jobs.job_title LIKE "%another_keyword%")
AND users.id = user_jobs.userid

Answer 2

You need to use parentheses in that query.

SELECT * FROM user_jobs,users WHERE user.id=user_jobs.userid
AND (user_jobs.job_title LIKE "%some_keyword%"
OR user_jobs.job_title LIKE "%another_keyword%")

Answer 3

First off, the AND operator holds precedence in this case. Isolate your logic like so:

SELECT * FROM user_jobs,users WHERE (user_jobs.job_title LIKE "%some_keyword%" OR user_jobs.job_title LIKE "%another_keyword%") AND user.id=user_jobs.userid

Second of all, don't use SELECT * FROM ... . This selects all your data, adding network overhead and taking up more time to transfer it all across the server.

Reference : https://dev.mysql.com/doc/refman/5.0/en/func-op-summary-ref.html

Answer 4

Even though you table contains 300 records it will result around 3000 records because you are selecting columns from both the tables but not giving any join condition in your query , so it will CROSS JOIN both the tables.

and for finding the `JOB_TITLE patter you can use Regular Expressions also as

SELECT * FROM USER_JOBS T1,USERS T2 WHERE REGEXP_LIKE(USER_JOBS.JOB_TITLE ,'SOME_KEYWORD|OTHER_KEYWORD') AND T2.ID=T1.USERID;