CODEWITHSUNDEEP
sql-server
Muhammad Ali
Muhammad Ali

Reputation: 873

Select Columns In Select Query Sql Server

Declare @tempvar as Varchar(10)
    Set @tempvar='true'

    select dbo.InformationTable.Name,dbo.InformationTable.Address,dbo.InformationTable.FavoriteDish
    from dbo.InformationTable

I want to show dbo.InformationTable.FavoriteDish column only when @tempvar is set to true,else it will not include in select statement?How can i achieve this.Thanks.

Upvotes: 2

Views: 81

Answers (1)

Crono
Crono

Reputation: 10478

Unfortunately there is no efficient way to conditionally exclude a column from a SELECT query.

You can either do it this way:

DECLARE @tempvar AS VARCHAR(10)
SET @tempvar='true'

IF @tempvar = 'true'
BEGIN
    SELECT
        dbo.InformationTable.Name,
        dbo.InformationTable.Address,
        dbo.InformationTable.FavoriteDish
    FROM
        dbo.InformationTable
END
ELSE
BEGIN
    SELECT
        dbo.InformationTable.Name,
        dbo.InformationTable.Address
    FROM
        dbo.InformationTable
END

Or, if you don't mind the column descending anyway as part of the resultset (with NULL values), like this:

SELECT
    dbo.InformationTable.Name,
    dbo.InformationTable.Address,
    CASE
        WHEN @tempvar = 'true' THEN
            dbo.InformationTable.FavoriteDish
        ELSE NULL
    END FavoriteDish
FROM
    dbo.InformationTable

You also could build your query dynamically in a VARCHAR variable and pass it to the EXEC method:

DECLARE @myquery VARCHAR(1000)

/*
Build your query here on your own conditions
*/

EXEC(@myquery)

I strongly advise against the last one, though, because it comes with multiple tradeoffs.

Hope that helps.

Upvotes: 1

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