Intro of SQL | #3 Subquery

이지수·2022년 2월 28일
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SQL

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1. Subqueries

  • so far all joins are additive joins
  • 2 joins will cover use a right table to determine which records to keep in the left table(오른쪽 표를 이용해서 왼쪽 표에 남겨둘 데이터를 결정)
  • use a way similar to a WHERE clause
SubqueriesDESCRIPTION
SEMI JOINMatches records by key field in the right table with those in the left
Then picks out only the rows in the left table that match that condition
ANTI JOINPicks out those columns in the left table that do not match the condition on the right table
SEMI JOIN and ANTI JOIN
SEMI JOIN & ANTI JOIN


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