[sql] WHERE Clause to find all records in a specific month

I want to be able to give a stored procedure a Month and Year and have it return everything that happens in that month, how do I do this as I can't compare between as some months have different numbers of days etc?

What's the best way to do this? Can I just ask to compare based on the year and month?

Thanks.

SELECT * FROM yourtable WHERE yourtimestampfield LIKE 'AAAA-MM%';

Where AAAA is the year you want and MM is the month you want

As an alternative to the MONTH and YEAR functions, a regular WHERE clause will work too:

select *
from yourtable
where '2009-01-01' <= datecolumn and datecolumn < '2009-02-01'

Can I just ask to compare based on the year and month?

You can. Here's a simple example using the AdventureWorks sample database...

DECLARE @Year       INT
DECLARE @Month      INT

SET @Year = 2002
SET @Month = 6

SELECT 
    [pch].* 
FROM 
    [Production].[ProductCostHistory]   pch
WHERE
    YEAR([pch].[ModifiedDate]) = @Year
AND MONTH([pch].[ModifiedDate]) = @Month

I find it easier to pass a value as a temporal data type (e.g. DATETIME) then use temporal functionality, specifically DATEADD and DATEPART, to find the start and end dates for the period, in this case the month e.g. this finds the start date and end date pair for the current month, just substitute CURRENT_TIMESTAMP for you parameter of of type DATETIME (note the 1990-01-01 value is entirely arbitrary):

SELECT DATEADD(M, 
          DATEDIFF(M, '1990-01-01T00:00:00.000', CURRENT_TIMESTAMP), 
          '1990-01-01T00:00:00.000'), 
       DATEADD(M, 
          DATEDIFF(M, '1990-01-01T00:00:00.000', CURRENT_TIMESTAMP), 
          '1990-01-31T23:59:59.997')

Something like this should do it:

select * from yourtable where datepart(month,field) = @month and datepart(year,field) = @year

Alternatively you could split month and year out into their own columns when creating the record and then select against them.

Iain

If you're using SQL Server, look into DATEPART.

http://msdn.microsoft.com/en-us/library/ms174420(SQL.90).aspx

DATEPART(mm, [THE DATE YOU'RE LOOKING AT])

You can then use normal integer logic with it. Same for year, just use yy instead of mm.

One way would be to create a variable that represents the first of the month (ie 5/1/2009), either pass it into the proc or build it (concatenate month/1/year). Then use the DateDiff function.

WHERE DateDiff(m,@Date,DateField) = 0

This will return anything with a matching month and year.

Using the MONTH and YEAR functions as suggested in most of the responses has the disadvantage that SQL Server will not be able to use any index there may be on your date column. This can kill performance on a large table.

I would be inclined to pass a DATETIME value (e.g. @StartDate) to the stored procedure which represents the first day of the month you are interested in.

You can then use

SELECT ... FROM ...
WHERE DateColumn >= @StartDate 
AND DateColumn < DATEADD(month, 1, @StartDate)

If you must pass the month and year as separate parameters to the stored procedure, you can generate a DATETIME representing the first day of the month using CAST and CONVERT then proceed as above. If you do this I would recommend writing a function that generates a DATETIME from integer year, month, day values, e.g. the following from a SQL Server blog.

create function Date(@Year int, @Month int, @Day int)
returns datetime
as
    begin
    return dateadd(month,((@Year-1900)*12)+@Month-1,@Day-1)
    end
go

The query then becomes:

SELECT ... FROM ...
WHERE DateColumn >= Date(@Year,@Month,1)
AND DateColumn < DATEADD(month, 1, Date(@Year,@Month,1))

More one tip very simple. You also could use to_char function, look:

For Month:

to_char(happened_at , 'MM') = 01

to_char(happened_at , 'YYYY') = 2009

to_char(happened_at , 'DD') = 01

to_char funcion is suported by sql language and not by one specific database.

I hope help anybody more...

Abs!