Calculate an expression

  • Hello, I need help to calculate an expression in sql.

    For example I have to send (248/5)*30 to a store procedure or to a function and the sp or the function has to return me the result, in this case is 1488.

  • You can use Dynamic SQL to handle the scenario

    But, be really careful about SQL Injection and take necessary steps to avoid it

    CREATE PROCEDURE dbo.usp_ShowExpressionResults

    (

    @Expression NVARCHAR(MAX)

    )

    AS

    BEGIN

    SET @Expression = 'SELECT ' + @Expression + ' AS Result'

    EXECUTE sp_executesql @Expression

    END


    Kingston Dhasian

    How to post data/code on a forum to get the best help - Jeff Moden
    http://www.sqlservercentral.com/articles/Best+Practices/61537/

  • sistemas_casinomnes (2/26/2013)


    Hello, I need help to calculate an expression in sql.

    For example I have to send (248/5)*30 to a store procedure or to a function and the sp or the function has to return me the result, in this case is 1488.

    Can you explain why the calculation has to be done in SQL?

    Here is one way. Create three variables in your package:

    1) Expression. A String which will contain the expression to be evaluated, eg (248/5)*30 in this case.

    2) Result. A Single which will contain the result.

    3) SQLExpression a String which is a calculated expression. Set the Expression as follows:

    "select " + @[User::Expression] + " Result"

    Notice that, if you click on Evaluate Expression, the result will be as follows:

    select (248/5)*30 Result

    Which is the query which will give you your result in T-SQL.

    Now create an ExecuteSQL task. Define the connection to your SQL Server instance and set SQLSourceType to variable. Set the source variable to be User::SQLExpression and set ResultSet to SingleRow.

    Now move to the Result Set section of the ExecuteSQL task and click on the Add button. Set Result Name to 'Result' and Variable name to User::Result.

    Done. When the ExecuteSQL task runs it will execute the SQL and store the result in 'Result'.

    Note that in this case, the result will be 1470, not 1488, as your expression will be performed using integer arithmetic.

    You can force T-SQL to do the calculation using real arithmetic by using something like this instead: (248.0 / 5) * 30

    The absence of evidence is not evidence of absence.
    Martin Rees

    You can lead a horse to water, but a pencil must be lead.
    Stan Laurel

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