how i can cast Command.ExecuteScalar() to nullable type ?

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C#

private static int GenerationId()
{
    OleDbCommand Command = new OleDbCommand();
    Command.Connection = ConnectionDB.OLEConnection;

    Command.CommandText = "Select MAX(Client_ID) from Client";
    ConnectionDB.OLEConnection.Open();


    int? Client_ID = (int?)CommandGenerationId.ExecuteScalar(); //i get exception here


    ConnectionDB.OLEConnection.Close();
    return (int)Client_ID;
}

Posted 22-Mar-13 9:31am

Anderso0on

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Bernhard Hiller 25-Mar-13 7:36am

By the way, the ID should be generated by the sql server - use an autoincrement column or something like that depending on your database system.
When you insert a new row into the table, you do not provide the id at all. You can query it afterwards with a SELECT @@Identity (or similar queries)

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ZurdoDev · Answer 1 · 2013-03-22T09:36:00

Solution 1

There are always many ways of doing things but this is how I do it:

C#

Object tempVal = CommandGenerationId.ExecuteScalar();
Int32 returnVal;

if (tempVal != null)
    returnVal = Int32.Parse(tempVal);

Something along those lines. For me, this approach works better than trying to cram it into a single line.

Posted 22-Mar-13 9:36am

ZurdoDev

Comments

Anderso0on 22-Mar-13 16:17pm

CommandGenerationId.ExecuteScalar()does not return null, it return {} when find nothig

ZurdoDev 22-Mar-13 16:24pm

If your query returns no records then tempVal will be null.