[Reproduced]mysql in the implementation line number, Oracle in the ROWID

MySQL's variable is required to implement line numbers, because MySQL Wood has rownumber.

The variable definition in MySQL can be used

Set @var =0

Or

Set @var: =0

can be used = or: = both, but if the variable is used in other statements, such as: Select then must be used: =, because = will be treated as a comparison symbol

1 Select @rownum: [Email protected]+1 as rownum, b.* from (select @rownum: =0) A, b

This is very useful, for example, to get a lot of rankings.

[Reproduced]mysql in the implementation line number, Oracle in the ROWID