SQL Server Bug Set "Custom Function and Group By"

zhaozj2021-02-16  90

/ ** == ** 1. Custom function is used for Group By error ** == ** /

- A simple function

Create Function F_STR (@str sysname, @ i int)

Returns char (1)

as begin

Return (Substring (@ Str, @ i, 1))

end

Go

- The following is a test

- Define Test Data Declare @t Table (Name Sysname) Insert Into @t Values ​​('ABCD')

- There is a group by the case, the result is incorrect a = dbo.f_str (name, 1), b = dbo.f_str (name, 2) from @tgroup by dbo.f_str (name, 1), dbo.f_str (Name ,2)

- There is no group by the situation, the result is correct Select a = dbo.f_str (name, 1), b = dbo.f_str (name, 2) from @TGO

- Delete Custom Function DROP FUNCTION F_STR

/ * - Test results A b ---- ---- a a

(The number of rows affects is 1 line)

A b ---- ---- a b

(The number of rows affects is 1 line) - * /

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