SQL Server Date Time Useful Functions

Here are some SQL Server Date Time Useful functions.

• DateCreate - Creates Date through Year, Month and Day
• DateToStrShort - Accepts Date and returns as '1-Jan-2009'
• DateGetDaysInMonth - Accepts Month and Year and returns number of days in month
• DateGetTimeOnly - Accepts date and returns time as '10:33 PM'
• DateGetDateOnly - Accepts Date and convert it into Date only i.e. removes the Time Part
• DateGetMonthFirstDate - Gets the first date of Month
• DateGetMonthLastDate - Gets the last date of Month
• DateGetMonthName - Gets the Month Name

Review the functions below or download the SQL file.

-- =============================================
-- Author:        Arsalan Tamiz
-- Description:   This function accepts Year, Month and Day
--                and returns Date
-- =============================================
CREATE FUNCTION [DateCreate]
(
    @Year int,
    @Month int,
    @Day int
)
RETURNS datetime
AS
BEGIN
    -- Declare the return variable here
    DECLARE @Result datetime;

    -- Add the T-SQL statements to compute the return value here
    SET @Result = CAST    (
                            CAST(@Year AS varchar(10)) + '-' +
                            CAST(@Month AS varchar(2)) + '-' + 
                            CAST(@Day AS varchar(2))
                            AS datetime
                          );

    -- Return the result of the function
    RETURN @Result;
END

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-- =============================================
-- Author:        Arsalan Tamiz
-- Description:   This function converts the given
--                date in to string. Useful function
--                for displaying date as '10-Jan-2009' for example
-- =============================================
CREATE FUNCTION [DateToStrShort] 
(
    -- Add the parameters for the function here
    @DateToConvert datetime
)
RETURNS varchar(50)
AS
BEGIN
    -- Declare the return variable here
    DECLARE @Result varchar(50)

    SET @Result = CAST(Day(@DateToConvert) AS varchar(50)) + '-' + 
                    Left(DateName(m, @DateToConvert), 3) + '-' + 
                    CAST(Year(@DateToConvert) AS varchar(50))

    -- Return the result of the function
    RETURN @Result;
END

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-- =============================================
-- Author:        unknown (I copied it from internet)
-- Description:   Returns the Days in a Month
--                parameters = Year and Month
-- =============================================
CREATE FUNCTION [DateGetDaysInMonth] (@Year int, @Month int)
RETURNS INT
AS
BEGIN

    RETURN CASE WHEN @Month IN (1, 3, 5, 7, 8, 10, 12) THEN 31
                WHEN @Month IN (4, 6, 9, 11) THEN 30
                ELSE CASE WHEN (@Year % 4    = 0 AND
                                @Year % 100 != 0) OR
                               (@Year % 400  = 0)
                          THEN 29
                          ELSE 28
                     END
           END

END

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-- =============================================
-- Author:  Arsalan Tamiz
-- Description: Gets the Time from Date
-- =============================================
CREATE FUNCTION [DateGetTimeOnly] 
(
 -- Add the parameters for the function here
 @DateToFormat datetime
)
RETURNS varchar(100)
AS
BEGIN
 -- Declare the return variable here
 DECLARE @Result varchar(100);
 
 DECLARE @H varchar(3);
 DECLARE @Hour int;
 DECLARE @M varchar(3); 

 SET @Hour = DatePart(hh, @DateToFormat);
 SET @M = DateName(mi, @DateToFormat);
 If @M = '0' SET @M = '00';

 -- Add the T-SQL statements to compute the return value here
 SET @H = CAST(CASE WHEN @Hour > 12 THEN @Hour - 12 ELSE CASE WHEN @Hour = 0 THEN 12 ELSE @Hour END END AS varchar);
 
 SET @Result = @H + ':' + @M + ' ' + CASE WHEN @Hour >= 12 THEN 'PM' ELSE 'AM' END;
 
 -- Return the result of the function
 RETURN @Result;
END

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-- =============================================
-- Author:  Arsalan Tamiz
-- Description: Returns Date only from given Date
--    That is removes the Time Part
--    so that we can compare two dates
-- =============================================
CREATE FUNCTION [DateGetDateOnly] 
(
 -- Add the parameters for the function here
 @DateToConvert datetime
)
RETURNS datetime
AS
BEGIN
 -- Declare the return variable here
 DECLARE @Result datetime;

 -- Add the T-SQL statements to compute the return value here
 SET @Result = CAST(CONVERT(varchar(100), @DateToConvert, 112) AS datetime);

 -- Return the result of the function
 RETURN @Result;
END

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-- =============================================
-- Author:  Arsalan Tamiz
-- Description: Gets the first date of month
-- =============================================
CREATE FUNCTION [DateGetMonthFirstDate] 
(
 -- Add the parameters for the function here
 @Month int
)
RETURNS datetime
AS
BEGIN
 -- Declare the return variable here
 DECLARE @Result datetime;
 DECLARE @Year int;

 SET @Year = Year(GetDate());

 SET @Result = CAST (
    CAST(@Year AS varchar(10)) + '-' + 
    CAST(@Month AS varchar(2)) + '-1' AS datetime
    );

 -- Return the result of the function
 RETURN @Result;
END

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-- =============================================
-- Author:  Arsalan Tamiz
-- Description: Returns last date of month
-- ***********************************************
-- IMPORTANT: This function depends on [dbo].[DateGetDaysInMonth]() function
--    which can be found above
-- ***********************************************
-- =============================================
CREATE FUNCTION [DateGetMonthLastDate] 
(
 -- Add the parameters for the function here
 @Month int
)
RETURNS datetime
AS
BEGIN
 -- Declare the return variable here
 DECLARE @Result datetime;
 DECLARE @Year int;
 
 SET @Year = Year(GetDate());
 
 SET @Result = CAST (
    CAST(@Year AS varchar(10)) + '-' + 
    CAST(@Month AS varchar(2)) + '-' +
    CAST([dbo].[DateGetDaysInMonth](@Year, @Month) AS varchar(2)) +
    AS datetime
    );

 -- Return the result of the function
 RETURN @Result;
END

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-- =============================================
-- Author:  Arsalan Tamiz
-- Description: This function Retuns the name of month
-- =============================================
CREATE FUNCTION [DateGetMonthName] 
(
 -- Add the parameters for the function here
 @Month int
)
RETURNS varchar(100)
AS
BEGIN
 -- Declare the return variable here
 DECLARE @Result varchar(100)
 DECLARE @d datetime;

 SET @d = CAST('2009-' + CAST(@Month AS varchar(2)) + '-1' AS datetime);

 -- Add the T-SQL statements to compute the return value here
 SET @Result = DateName(mm, @d);

 -- Return the result of the function
 RETURN @Result;
END

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