Solomon » SQL Server

COALESCE function instead of long CASE WHEN … ELSE (T-SQL)

Solomon — Wed, 27 Apr 2011 17:35:09 +0000

Instead of using long “SELECT … CASE WHEN … ELSE …” construction, you can use the COALESCE function when you need to find a value that is not NULL. Lets review the following T-SQL expression, in which we need to select an available “source”:

http://dotnettipoftheday.org/tips/sql-coalesce.aspx

SELECT TheSource =
   CASE
      WHEN localSource IS NOT NULL THEN localSource
      WHEN intranetSource IS NOT NULL THEN intranetSource
      WHEN internetSource IS NOT NULL THEN internetSource
      ELSE ''
   END
FROM ...

Now lets rewrite the code above using COALESCE function:

SELECT TheSource =
   COALESCE(localSource, intranetSource, internetSource, '')
FROM ...

The tip applies to MS SQL Server 2000/2005.

SQL Server Date Formats

Solomon — Wed, 27 Apr 2011 08:11:39 +0000

Standard Date Formats
Date Format	Standard	SQL Statement	Sample Output
Mon DD YYYY ¹ HH:MIAM (or PM)	Default	SELECT CONVERT(VARCHAR(20), GETDATE(), 100)	Jan 1 2005 1:29PM ¹
MM/DD/YY	USA	SELECT CONVERT(VARCHAR(8), GETDATE(), 1) AS [MM/DD/YY]	11/23/98
MM/DD/YYYY	USA	SELECT CONVERT(VARCHAR(10), GETDATE(), 101) AS [MM/DD/YYYY]	11/23/1998
YY.MM.DD	ANSI	SELECT CONVERT(VARCHAR(8), GETDATE(), 2) AS [YY.MM.DD]	72.01.01
YYYY.MM.DD	ANSI	SELECT CONVERT(VARCHAR(10), GETDATE(), 102) AS [YYYY.MM.DD]	1972.01.01
DD/MM/YY	British/French	SELECT CONVERT(VARCHAR(8), GETDATE(), 3) AS [DD/MM/YY]	19/02/72
DD/MM/YYYY	British/French	SELECT CONVERT(VARCHAR(10), GETDATE(), 103) AS [DD/MM/YYYY]	19/02/1972
DD.MM.YY	German	SELECT CONVERT(VARCHAR(8), GETDATE(), 4) AS [DD.MM.YY]	25.12.05
DD.MM.YYYY	German	SELECT CONVERT(VARCHAR(10), GETDATE(), 104) AS [DD.MM.YYYY]	25.12.2005
DD-MM-YY	Italian	SELECT CONVERT(VARCHAR(8), GETDATE(), 5) AS [DD-MM-YY]	24-01-98
DD-MM-YYYY	Italian	SELECT CONVERT(VARCHAR(10), GETDATE(), 105) AS [DD-MM-YYYY]	24-01-1998
DD Mon YY ¹	-	SELECT CONVERT(VARCHAR(9), GETDATE(), 6) AS [DD MON YY]	04 Jul 06 ¹
DD Mon YYYY ¹	-	SELECT CONVERT(VARCHAR(11), GETDATE(), 106) AS [DD MON YYYY]	04 Jul 2006 ¹
Mon DD, YY ¹	-	SELECT CONVERT(VARCHAR(10), GETDATE(), 7) AS [Mon DD, YY]	Jan 24, 98 ¹
Mon DD, YYYY ¹	-	SELECT CONVERT(VARCHAR(12), GETDATE(), 107) AS [Mon DD, YYYY]	Jan 24, 1998 ¹
HH:MM:SS	-	SELECT CONVERT(VARCHAR(8), GETDATE(), 108)	03:24:53
Mon DD YYYY HH:MI:SS:MMMAM (or PM) ¹	Default + milliseconds	SELECT CONVERT(VARCHAR(26), GETDATE(), 109)	Apr 28 2006 12:32:29:253PM ¹
MM-DD-YY	USA	SELECT CONVERT(VARCHAR(8), GETDATE(), 10) AS [MM-DD-YY]	01-01-06
MM-DD-YYYY	USA	SELECT CONVERT(VARCHAR(10), GETDATE(), 110) AS [MM-DD-YYYY]	01-01-2006
YY/MM/DD	-	SELECT CONVERT(VARCHAR(8), GETDATE(), 11) AS [YY/MM/DD]	98/11/23
YYYY/MM/DD	-	SELECT CONVERT(VARCHAR(10), GETDATE(), 111) AS [YYYY/MM/DD]	1998/11/23
YYMMDD	ISO	SELECT CONVERT(VARCHAR(6), GETDATE(), 12) AS [YYMMDD]	980124
YYYYMMDD	ISO	SELECT CONVERT(VARCHAR(8), GETDATE(), 112) AS [YYYYMMDD]	19980124
DD Mon YYYY HH:MM:SS:MMM(24h) ¹	Europe default + milliseconds	SELECT CONVERT(VARCHAR(24), GETDATE(), 113)	28 Apr 2006 00:34:55:190 ¹
HH:MI:SS:MMM(24H)	-	SELECT CONVERT(VARCHAR(12), GETDATE(), 114) AS [HH:MI:SS:MMM(24H)]	11:34:23:013
YYYY-MM-DD HH:MI:SS(24h)	ODBC Canonical	SELECT CONVERT(VARCHAR(19), GETDATE(), 120)	1972-01-01 13:42:24
YYYY-MM-DD HH:MI:SS.MMM(24h)	ODBC Canonical (with milliseconds)	SELECT CONVERT(VARCHAR(23), GETDATE(), 121)	1972-02-19 06:35:24.489
YYYY-MM-DDTHH:MM:SS:MMM	ISO8601	SELECT CONVERT(VARCHAR(23), GETDATE(), 126)	1998-11-23T11:25:43:250
DD Mon YYYY HH:MI:SS:MMMAM ¹	Kuwaiti	SELECT CONVERT(VARCHAR(26), GETDATE(), 130)	28 Apr 2006 12:39:32:429AM ¹
DD/MM/YYYY HH:MI:SS:MMMAM	Kuwaiti	SELECT CONVERT(VARCHAR(25), GETDATE(), 131)	28/04/2006 12:39:32:429AM

Extended Date Formats
Date Format	SQL Statement	Sample Output
YY-MM-DD	SELECT SUBSTRING(CONVERT(VARCHAR(10), GETDATE(), 120), 3, AS [YY-MM-DD] SELECT REPLACE(CONVERT(VARCHAR(8), GETDATE(), 11), ‘/’, ‘-’) AS [YY-MM-DD]	99-01-24
YYYY-MM-DD	SELECT CONVERT(VARCHAR(10), GETDATE(), 120) AS [YYYY-MM-DD] SELECT REPLACE(CONVERT(VARCHAR(10), GETDATE(), 111), ‘/’, ‘-’) AS [YYYY-MM-DD]	1999-01-24
MM/YY	SELECT RIGHT(CONVERT(VARCHAR(8), GETDATE(), 3), 5) AS [MM/YY] SELECT SUBSTRING(CONVERT(VARCHAR(8), GETDATE(), 3), 4, 5) AS [MM/YY]	08/99
MM/YYYY	SELECT RIGHT(CONVERT(VARCHAR(10), GETDATE(), 103), 7) AS [MM/YYYY]	12/2005
YY/MM	SELECT CONVERT(VARCHAR(5), GETDATE(), 11) AS [YY/MM]	99/08
YYYY/MM	SELECT CONVERT(VARCHAR(7), GETDATE(), 111) AS [YYYY/MM]	2005/12
Month DD, YYYY ¹	SELECT DATENAME(MM, GETDATE()) + RIGHT(CONVERT(VARCHAR(12), GETDATE(), 107), 9) AS [Month DD, YYYY]	July 04, 2006 ¹
Mon YYYY ¹	SELECT SUBSTRING(CONVERT(VARCHAR(11), GETDATE(), 113), 4, AS [Mon YYYY]	Apr 2006 ¹
Month YYYY ¹	SELECT DATENAME(MM, GETDATE()) + ‘ ‘ + CAST(YEAR(GETDATE()) AS VARCHAR(4)) AS [Month YYYY]	February 2006 ¹
DD Month ¹	SELECT CAST(DAY(GETDATE()) AS VARCHAR(2)) + ‘ ‘ + DATENAME(MM, GETDATE()) AS [DD Month]	11 September ¹
Month DD ¹	SELECT DATENAME(MM, GETDATE()) + ‘ ‘ + CAST(DAY(GETDATE()) AS VARCHAR(2)) AS [Month DD]	September 11 ¹
DD Month YY ¹	SELECT CAST(DAY(GETDATE()) AS VARCHAR(2)) + ‘ ‘ + DATENAME(MM, GETDATE()) + ‘ ‘ + RIGHT(CAST(YEAR(GETDATE()) AS VARCHAR(4)), 2) AS [DD Month YY]	19 February 72 ¹
DD Month YYYY ¹	SELECT CAST(DAY(GETDATE()) AS VARCHAR(2)) + ‘ ‘ + DATENAME(MM, GETDATE()) + ‘ ‘ + CAST(YEAR(GETDATE()) AS VARCHAR(4)) AS [DD Month YYYY]	11 September 2002 ¹
MM-YY	SELECT RIGHT(CONVERT(VARCHAR(8), GETDATE(), 5), 5) AS [MM-YY] SELECT SUBSTRING(CONVERT(VARCHAR(8), GETDATE(), 5), 4, 5) AS [MM-YY]	12/92
MM-YYYY	SELECT RIGHT(CONVERT(VARCHAR(10), GETDATE(), 105), 7) AS [MM-YYYY]	05-2006
YY-MM	SELECT RIGHT(CONVERT(VARCHAR(7), GETDATE(), 120), 5) AS [YY-MM] SELECT SUBSTRING(CONVERT(VARCHAR(10), GETDATE(), 120), 3, 5) AS [YY-MM]	92/12
YYYY-MM	SELECT CONVERT(VARCHAR(7), GETDATE(), 120) AS [YYYY-MM]	2006-05
MMDDYY	SELECT REPLACE(CONVERT(VARCHAR(10), GETDATE(), 1), ‘/’, ”) AS [MMDDYY]	122506
MMDDYYYY	SELECT REPLACE(CONVERT(VARCHAR(10), GETDATE(), 101), ‘/’, ”) AS [MMDDYYYY]	12252006
DDMMYY	SELECT REPLACE(CONVERT(VARCHAR(10), GETDATE(), 3), ‘/’, ”) AS [DDMMYY]	240702
DDMMYYYY	SELECT REPLACE(CONVERT(VARCHAR(10), GETDATE(), 103), ‘/’, ”) AS [DDMMYYYY]	24072002
Mon-YY ¹	SELECT REPLACE(RIGHT(CONVERT(VARCHAR(9), GETDATE(), 6), 6), ‘ ‘, ‘-’) AS [Mon-YY]	Sep-02 ¹
Mon-YYYY ¹	SELECT REPLACE(RIGHT(CONVERT(VARCHAR(11), GETDATE(), 106), 8), ‘ ‘, ‘-’) AS [Mon-YYYY]	Sep-2002 ¹
DD-Mon-YY ¹	SELECT REPLACE(CONVERT(VARCHAR(9), GETDATE(), 6), ‘ ‘, ‘-’) AS [DD-Mon-YY]	25-Dec-05 ¹
DD-Mon-YYYY ¹	SELECT REPLACE(CONVERT(VARCHAR(11), GETDATE(), 106), ‘ ‘, ‘-’) AS [DD-Mon-YYYY]	25-Dec-2005 ¹

¹ To make the month name in upper case, simply use the UPPER string function.

Comma Delimited Output – single select statement – SQL Server

Solomon — Fri, 20 Aug 2010 11:07:14 +0000

We can get a comma delimited output from a single select statement in SQL Server by using the following SQL Script.


select  stuff(( select  ',' + CountryRegionCode
                from    Person.CountryRegion
              for
                xml path('')
              ), 1, 1, '') as CodeList

Comma-Delimited Output (SQL Server)

Solomon — Sat, 02 May 2009 10:26:00 +0000

Using Query:


use Northwind
GO

declare @CustIDs varchar(8000)

select top 10
        @CustIDs = isnull(@CustIDs + ',', '') + CustomerID
from    Customers

select  @CustIDs

GO

Using Cursor:


declare cCustomerIDs cursor for

select [CustomerID] from [dbo].[Customers] order by [CustomerID]

declare @CustomerIDs varchar(8000)

declare @CustomerID varchar(10)

open cCustomerIDs

fetch next from cCustomerIDs into @CustomerID

while @@FETCH_STATUS = 0
    begin

        set @CustomerIDs = isnull(@CustomerIDs + ',', '') + @CustomerID

        fetch next from cCustomerIDs into @CustomerID

    end

close cCustomerIDs

deallocate cCustomerIDs

select  @CustomerIDs as CustomerIDs

GO

Find the balance amount (sum(credit) – sum(debit)) from the following table?

Solomon — Tue, 24 Feb 2009 04:44:11 +0000

Ans: find out the balance amount of account no: 1


select  a.SumCr as Credit ,
        b.SumDr as Debit ,
        a.SumCr - b.SumDr as Balance
from    ( select    sum(A_Amount) as SumCr
          from      tblAccount
          where     A_ID = 1
                    and A_Type = 'Cr'
        ) a ,
        ( select    sum(A_Amount) as SumDr
          from      tblAccount
          where     A_ID = 1
                    and A_Type = 'Dr'
        ) b

Ans: find out the balance amount for all the account numbers in the table:


select  a.A_ID as ID ,
        a.SumCr as Credit ,
        b.SumDr as Debit ,
        a.SumCr - b.SumDr as Balance
from    ( select    A_ID ,
                    sum(A_Amount) as SumCr
          from      tblAccount
          where     A_Type = 'Cr'
          group by  A_ID
        ) a
        inner join ( select A_ID ,
                            sum(A_Amount) as SumDr
                     from   tblAccount
                     where  A_Type = 'Dr'
                     group by A_ID
                   ) b on a.A_ID = b.A_ID

Find out the N’th maxium salary?

Solomon — Tue, 24 Feb 2009 04:42:25 +0000

Ans: find the 5^th maxium salary:

   1: SELECT TOP 1 * FROM tblEmployee WHERE E_Salary NOT IN

   2:     (SELECT DISTINCT TOP 4 E_Salary FROM tblEmployee ORDER BY E_Salary DESC)

   3:     ORDER BY E_Salary DESC