如果使用SQL函数让公历转农历，应该如何写这个函数呢？下面就将为您介绍让公历变农历的SQL函数写法，供您参考，希望对您学习SQL有所帮助。

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE FUNCTION [dbo].[fn_GetLunar1](
@solarDay DATETIME)
RETURNS varchar(200)

AS
BEGIN
DECLARE @solData int
DECLARE @offset int
DECLARE @iLunar int
DECLARE @i INT
DECLARE @j INT
DECLARE @yDays int
DECLARE @mDays int
DECLARE @mLeap int
DECLARE @mLeapNum int
DECLARE @bLeap smallint
DECLARE @temp int

DECLARE @YEAR INT
DECLARE @MONTH INT
DECLARE @DAY INT

DECLARE @OUTPUTDATE varchar(100)

--保证传进来的日期是不带时间
SET @solarDay=cast(@solarDay AS char(10))
SET @offset=CAST(@solarDay-'1900-01-30' AS INT)

--确定农历年开始
SET @i=1900
--SET @offset=@solData
WHILE @i<2050 AND @offset>0
BEGIN
SET @yDays=348
SET @mLeapNum=0
SELECT @iLunar=dataInt FROM SolarData WHERE yearId=@i

--传回农历年的总天数
SET @j=32768
WHILE @j>8
BEGIN
IF @iLunar & @j >0
SET @yDays=@yDays+1
SET @j=@j/2
END

--传回农历年闰哪个月 1-12 , 没闰传回 0
SET @mLeap = @iLunar & 15

--传回农历年闰月的天数 ,加在年的总天数上
IF @mLeap > 0
BEGIN
IF @iLunar & 65536 > 0
SET @mLeapNum=30
ELSE
SET @mLeapNum=29

SET @yDays=@yDays+@mLeapNum
END

SET @offset=@offset-@yDays
SET @i=@i+1
END

IF @offset <= 0
BEGIN
SET @offset=@offset+@yDays
SET @i=@i-1
END
--确定农历年结束
SET @YEAR=@i

--确定农历月开始
SET @i = 1
SELECT @iLunar=dataInt FROM SolarData WHERE yearId=@YEAR

--判断那个月是润月
SET @mLeap = @iLunar & 15
SET @bLeap = 0

WHILE @i < 13 AND @offset > 0
BEGIN
--判断润月
SET @mDays=0
IF (@mLeap > 0 AND @i = (@mLeap+1) AND @bLeap=0)
BEGIN--是润月
SET @i=@i-1
SET @bLeap=1
--传回农历年闰月的天数
IF @iLunar & 65536 > 0
SET @mDays = 30
ELSE
SET @mDays = 29
END
ELSE
--不是润月
BEGIN
SET @j=1
SET @temp = 65536
WHILE @j<=@i
BEGIN
SET @temp=@temp/2
SET @j=@j+1
END

IF @iLunar & @temp > 0
SET @mDays = 30
ELSE
SET @mDays = 29
END

--解除闰月
IF @bLeap=1 AND @i= (@mLeap+1)
SET @bLeap=0

SET @offset=@offset-@mDays
SET @i=@i+1
END

IF @offset <= 0
BEGIN
SET @offset=@offset+@mDays
SET @i=@i-1
END

--确定农历月结束
SET @MONTH=@i

--确定农历日结束
SET @DAY=@offset
if @bLeap=1
SET @OUTPUTDATE=convert(varchar(10),CAST((CAST(@YEAR AS VARCHAR(4))+'-'+CAST(@MONTH AS VARCHAR(2))+'-'+CAST(@DAY AS VARCHAR(2))) AS DATETIME) ,120)+',1'
else
SET @OUTPUTDATE=convert(varchar(10),CAST((CAST(@YEAR AS VARCHAR(4))+'-'+CAST(@MONTH AS VARCHAR(2))+'-'+CAST(@DAY AS VARCHAR(2))) AS DATETIME) ,120)+',0'
RETURN @OUTPUTDATE
END

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