sql中获取字符串中的字母,数字,非数字函数

sql获取字母:
CREATE FUNCTION dbo.F_Get_STR (@S VARCHAR(100))
RETURNS VARCHAR(100)
AS
BEGIN
    WHILE PATINDEX('%[^a-z]%',@S)>0
          BEGIN
                set @s=stuff(@s,patindex('%[^a-z]%',@s),1,'')
          END
    RETURN @S
END
GO
sql获取数字:
create function dbo.F_Get_Number (@S varchar(100))
returns int
AS
begin
    while PATINDEX('%[^0-9]%',@S)>0
          begin
                set @s=stuff(@s,patindex('%[^0-9]%',@s),1,'')
          end
    return cast(@S as int)
end
Go
sql获取非数字:
create function dbo.F_Get_NANnumber (@S varchar(100))
returns varchar(500)
AS
begin
    while PATINDEX('%[0-9]%',@S)>0
          begin
                set @s=stuff(@s,patindex('%[0-9]%',@s),1,'')
          end
    return @s
end
GO