CODEWITHSUNDEEP
sql
MyNameHere
MyNameHere

Reputation: 305

When talking about ANSI SQL, is there a difference between JOIN and LEFT JOIN?

I had an interview today where they asked the question, "Tell me the difference between a JOIN and INNER JOIN." I proceeded to explain what INNER JOIN is, and started to talk about LEFT JOIN. The interviewer interrupted me and said, "No I didn't say LEFT JOIN, just JOIN." I was honestly stuck because I never used "JOIN" I always specified LEFT JOIN.

He told me that LEFT JOIN and JOIN act the same. When looking up "JOIN" I can't find any information saying that it works just like left join.

Does JOIN work the same as LEFT JOIN? Is it normal, for tech/IT jobs, to have trick questions like this?

Upvotes: 0

Views: 55

Answers (1)

Gordon Linoff
Gordon Linoff

Reputation: 1269503

Plain old JOIN is a synonym for INNER JOIN. That is quite different from a LEFT JOIN

SQL implements through explicit syntax five JOIN operations:

  • CROSS JOIN
  • INNER JOIN
  • LEFT JOIN
  • RIGHT JOIN
  • FULL JOIN

In addition, "join" can colloquially mean "combining rows from two tables" and there are other join types -- such as semi-joins.

Upvotes: 1

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