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Editor to share with you the problem of MySQL custom variables to achieve row_number analysis function examples, I hope you will learn something after reading this article, let's discuss it together!

MySQL often uses custom variables to implement complex queries, such as row_number 's ability to add line numbers by group.

But there is a sinkhole in it. It's not deep.

Take a look at the test first.

Create table tmp_num (gid int, score int); create table tmp_var (gid varchar (32), score int); insert into tmp_numselect id%4,ceil (1000*rand ()) from nums where id

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