Shulou(Shulou.com)05/31 Report--

This article introduces the relevant knowledge of "how to understand MySQL subquery". Many people will encounter such a dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Description

1. Select statements that appear in other statements are called subqueries or internal queries.

2. When multi-table association or intra-table field association, or when making similar function judgment, subqueries are often used to solve the corresponding problems.

Grammar

# external query SELECT "field 1" FROM "table 1" WHERE "field 2" [comparison operator] # query (SELECT "field 1" FROM "table 2" WHERE "condition); # can be the operator of a symbol, such as =, >, =,

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