Strange Behavior with SqlDataReader and long columns

Question

I stumbled across this thing today:

I have a little helper method with the following:

private static T GetValOrDefault<T>(this IDataRecord rdr, string name)
{
    return rdr[name] is T ? (T) rdr[name] : default(T);
}

and all my models use public long Id { get; set; }

SQL server columns are BIGINT

Somehow the GetValOrDefault<long>("Id") returns '0', and i went ahead and used the Immediate Window there, and had a look at rdr["Id"].GetType()

It was Int32... any ideas why that happens? Everywhere i look, it says BIGINT = INT64 = long... and somehow the SqlDataReader gives me int32...

Edit:
That is my Sql Query:

    SELECT
        Id,
        Created,
        CreatedById,
        LastModified,
        LastModifiedById,
        Deleted,
        DeletedById
    FROM dbo.MyTable
    WHERE Id = @id

to StackOverflow · Accepted Answer · 2013-11-14 08:04:48Z

2

A BIGINT column should be returned as a long. I suspect a bug in your code - perhaps you're not getting the column you think you are, from the database you think you are using, or perhaps your SQL query is casting the column value.

answered Nov 14, 2013 at 8:04

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1 Comment

Nefarion Over a year ago

you were right, i used a temp table with DECLARE @temp AS TABLE(Id int

Kain · Accepted Answer · 2013-11-14 06:55:46Z

1

your can use Convert.ChnageType implement

public T Change<T>(IDataReader rd,string fieldName)
{
    return (T)Convert.ChangeType(rd[fieldName], typeof(T));
}

answered Nov 14, 2013 at 6:55

Kain

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