Selecting one or all records in a stored procedure

I am trying to do a stored procedure where when a you have a value then it returns one record but if no value is inserted into the stored procedure, it returns all records.  So here is my stored procedure:

ALTER PROCEDURE
[dbo].[SP_SelectAllContinentsLoc]
@continentName      nvarchar(50)
AS
SELECT continentId, continentName
FROM
dbo.tblcontinents
WHERE
continentName = @continentName


So how would I set it that if @continentName is null, it returns all records?  Thanks!
VBBRettAsked:
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LIONKINGConnect With a Mentor Commented:
You can also try something like this:

ALTER PROCEDURE 
[dbo].[SP_SelectAllContinentsLoc]
@continentName      nvarchar(50)
AS
SELECT continentId, continentName
FROM
dbo.tblcontinents
WHERE
ISNULL(@continentName, continentName) = continentName

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Chris LuttrellConnect With a Mentor Senior Database ArchitectCommented:
ALTER PROCEDURE 
[dbo].[SP_SelectAllContinentsLoc]
@continentName      nvarchar(50) = NULL
AS
SELECT continentId, continentName
FROM
dbo.tblcontinents
WHERE
@continentName IS NULL
OR
continentName = @continentName

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Now you can pass in NULL or not supply it at all and it should return all records from tblcontinents
0
 
harshada_sonawaneConnect With a Mentor Commented:
u can use if else

ALTER PROCEDURE
[dbo].[SP_SelectAllContinentsLoc]
@continentName      nvarchar(50) = NULL
AS
if @continentName is null
    SELECT continentId, continentName
    FROM
    dbo.tblcontinents
else
     SELECT continentId, continentName
    FROM
    dbo.tblcontinents where continentName = @continentName
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Chris LuttrellSenior Database ArchitectCommented:
I do not really recommend making a practice of using IF/ELSE with 2 selects in a stored procedure as it will cause performance issues with the optimizer and stored execution plans depending on which path is taken the first time the Procedure is called, but that is a much larger discussion.
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Alpesh PatelConnect With a Mentor Assistant ConsultantCommented:
SELECT TOP
            (CASE WHEN (SELECT COUNT(1) FROM
            dbo.tblcontinents where continentName = @continentName)) > 0 THEN  (SELECT COUNT(1) FROM
            dbo.tblcontinents where continentName = @continentName) ELSE (SELECT COUNT(1) FROM
            dbo.tblcontinents) END )
      continentId, continentName
FROM
      dbo.tblcontinents
WHERE
      continentName = @continentName
0
 
Anthony PerkinsCommented:
I do not really recommend making a practice of using IF/ELSE with 2 selects
Actually I suspect it would actually perform better.  The real problem is that I suspect that this is not just a simple case of 2 SELECTs, but rather could morph into something much more complex.
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