计算两个时间相差多少年月日的sql算法

 1 /****** Object:  StoredProcedure [dbo].[GetDateDiff]    Script Date: 11/12/2019 16:14:05 ******/
 2 SET ANSI_NULLS ON
 3 GO
 4 SET QUOTED_IDENTIFIER ON
 5 GO
 6 --计算两个时间相差多少年月日的sql算法，用于新生儿年龄计算
 7 ALTER PROCEDURE [dbo].[GetDateDiff]
 8     @fromDate NVARCHAR(10) ,--开始日期
 9     @toDate NVARCHAR(10)    --结束日期
10 AS 
11     DECLARE @YearDiff INTEGER
12     DECLARE @MonthDiff INTEGER
13     DECLARE @DayDiff INTEGER
14     DECLARE @ToMonth INTEGER
15     DECLARE @FromDay INTEGER
16     DECLARE @ToDay INTEGER
17 
18 
19     SET @YearDiff = LTRIM(DATEDIFF(yy, @fromDate, @toDate))
20     SET @MonthDiff = LTRIM(DATEDIFF(mm, @fromDate, @toDate) % 12)
21     SET @ToMonth = MONTH(CAST(@toDate AS DATETIME))
22     SET @FromDay = DAY(CAST(@fromDate AS DATETIME))
23     SET @ToDay = DAY(CAST(@ToDate AS DATETIME))
24     IF ( @ToDay - @FromDay ) < 0 
25         BEGIN
26             IF ( @ToMonth - 1 ) = 1
27                 OR ( @ToMonth - 1 ) = 3
28                 OR ( @ToMonth - 1 ) = 5
29                 OR ( @ToMonth - 1 ) = 7
30                 OR ( @ToMonth - 1 ) = 8
31                 OR ( @ToMonth - 1 ) = 10
32                 OR ( @ToMonth - 1 ) = 12 
33                 BEGIN
34                     SET @DayDiff = 31 + @Today - @FromDay
35                     SET @MonthDiff = @MonthDiff - 1
36                 END    
37             ELSE 
38                 BEGIN
39                     SET @DayDiff = 30 + @Today - @FromDay
40                     SET @MonthDiff = @MonthDiff - 1
41                 END
42         END
43     ELSE 
44         BEGIN
45             SET @DayDiff = @Today - @FromDay
46         END
47         
48     SELECT  CAST(@YearDiff AS NVARCHAR(10)) + '岁'
49             + CAST(@MonthDiff AS NVARCHAR(10)) + '个月'
50             + CAST(@DayDiff AS NVARCHAR(10)) + '天'        
51