sql 自定义函数--十进制转二进制

随笔记忆:

 if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[DECTOBIN]') and xtype in (N'FN', N'IF', N'TF'))
 drop function [dbo].[DECTOBIN]
 GO

 SET QUOTED_IDENTIFIER ON
 GO
 SET ANSI_NULLS ON
 GO

 create FUNCTION dbo.DECTOBIN(@Dec INT, @StrLen INT)
 RETURNS VARCHAR(31)
 AS
 BEGIN
     DECLARE @BinStr AS VARCHAR(31)
     DECLARE @Div2 AS INT
     DECLARE @Mod2 AS INT
     IF @Dec < 0
         RETURN 'NULL'
     SET @Div2 = @Dec / 2
     SET @Mod2 = @Dec % 2
     SET @BinStr = ''
     WHILE @Div2 <> 0
     BEGIN
         SET @BinStr = CAST(@Mod2 AS CHAR(1)) + @BinStr
         SET @Dec = @Dec / 2
         SET @Div2 = @Dec / 2
         SET @Mod2 = @Dec % 2

     END;
     SET @BinStr = CAST(@Mod2 AS CHAR(1)) + @BinStr
     IF @StrLen > LEN(@BinStr)
         BEGIN
             IF @StrLen > 31
                 SET @StrLen = 31

             DECLARE @ZeroStr VARCHAR(31)
             DECLARE @OffsetLen TINYINT
             SET @ZeroStr = ''
             SET @OffsetLen = @StrLen - LEN(@BinStr)

             WHILE  @OffsetLen > 0
             BEGIN
                 SET @ZeroStr = @ZeroStr + ''
                 SET @OffsetLen = @OffsetLen - 1
             END

             SET @BinStr = @ZeroStr + @BinStr
         END
     RETURN @BinStr

 END

 GO
 SET QUOTED_IDENTIFIER OFF
 GO
 SET ANSI_NULLS ON
 GO