sql通过日期判断年龄函数的示例代码

定义函数：

CREATE FUNCTION [dbo].[GetAge]  
(  
@BirthDay nvarchar(20) --生日  
)  
RETURNS varchar(20)  
AS  
BEGIN  
if(@BirthDay is NUlL or @BirthDay='')
return '';
-- Declare the return variable here  
DECLARE @age varchar(20)  
DECLARE @years int  
DECLARE @months int  
DECLARE @days int  
-- Add the T-SQL statements to compute the return value here  
set @age = ''  

set @years = year(GETDATE()) - year(@birthday)  
set @months = month(GETDATE()) - month(@birthday)  
if day(@birthday)<=day(GETDATE())  
  set @days = day(GETDATE()) - day(@birthday)  
else  
  begin  
    set @months = @months - 1  
    if MONTH(@birthday) in (1,3,5,7,8,10,12)  
      set @days = 31-day(@birthday)+day(GETDATE())  
    else if MONTH(@birthday) in (4,6,9,11)  
      set @days = 30-day(@birthday)+day(GETDATE())  
    else if MONTH(@birthday) = 2  
      if (year(@birthday)％4 = 0 and year(@birthday)％100 <> 0) or year(@birthday)％400 = 0  
        set @days = 29-day(@birthday)+day(GETDATE())  
      else  
        set @days = 28-day(@birthday)+day(GETDATE())  
  end  
if @months < 0  
  begin  
    set @years = @years - 1  
    set @months = @months + 12  
  end  
if @years = 0 and @months = 0  
begin  
    return convert(varchar,@days+1) + '天'  
 end  
if @years > 0  
  set @age = cast(@years as varchar(5)) + '岁'  
if @years < 3 and @months > 0 and @years>-1  
begin  
  set @age = @age + cast(@months as varchar(5)) + '月'  
end  
if @years<0  
set @age=''  
RETURN @age  
END

使用函数：

来源：https://www.cnblogs.com/Allofus/p/15016007.html