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 + '0'
                SET @OffsetLen = @OffsetLen - 1
            END
   
            SET @BinStr = @ZeroStr + @BinStr
        END
    RETURN @BinStr

END


GO
SET QUOTED_IDENTIFIER OFF 
GO
SET ANSI_NULLS ON 
GO