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SQL code:

select case (select count(*) from tb1 where uid=9) as t when t > 0 then (select * from tb2) else (select * from tb3) end

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SQL codeselectcase (selectcount(*)from tb1where uid=9)as twhen t>0then (select*from tb2)else (select*from tb3)end

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SQL code

select case (select count(*) from tb1 where uid=9) as t when t > 0 then (select * from tb2) else (select * from tb3) end

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SQL code

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