Why do we have OUTER clause in LEFT JOIN?
join, mysql, sql, sql-server
Solution
There is no difference. The `OUTER` keyword is optional.
Problem
What the difference between the 2 queries below UPDATE This question is already answered in a similar question here LEFT JOIN vs. LEFT OUTER JOIN in SQL Server. ``` SELECT * FROM ca LEFT JOIN exam ON ca.subject = exam.subject ``` and ``` SELECT * FROM ca LEFT OUTER JOIN exam ON ca.subject = exam.subject ``` Tables ``` Table 'CA' -------------------- subject|score ---------------- ENG |25 MTH |34 BIO |18 Table 'Exam' -------------------- subject|score ---------------- ENG |25 ``` Running the 2 queries produce the same result in mysql, sqlserver 2008. I didn't test in Oracle. ``` subject | score1 | subject | score1 -------------------------------------- ENG 14 ENG 44 MTH 28 NULL NULL BIO 22 NULL NULL ``` What's the purpose of that OUTER clause