SqlDataReader with no rows.

[me]

I am using a sqldatareader with this command:

select max(id) from x

If there is no rows in table x then using
sqldatareader.read() still return true as if
there is a row, which means this code breaks:

if (sqldatareader.read()) {
... = sqldatareader.GetInt32(0); // field 0 is null!?
}

All the examples i have seen on ms website and
in books dont take any precautions for empty
tables. Right now i am doing this:

if (sqldatareader.read() && !sqldatareader.IsDBNull(0)) {
... = sqldatareader.GetInt32(0);
}

It seems clumsy. I am doing somthing wrong here?

 

[Jon Skeet [C# MVP]]

I am using a sqldatareader with this command:

select max(id) from x

If there is no rows in table x then using
sqldatareader.read() still return true as if
there is a row, which means this code breaks:

if (sqldatareader.read()) {
... = sqldatareader.GetInt32(0); // field 0 is null!?
}

All the examples i have seen on ms website and
in books dont take any precautions for empty
tables. Right now i am doing this:

if (sqldatareader.read() && !sqldatareader.IsDBNull(0)) {
... = sqldatareader.GetInt32(0);
}

It seems clumsy. I am doing somthing wrong here?

Nope - the result of your select is *exactly* a table with a single
row, which has a null value. If you execute the query in SQL Server
Enterprise Manager you'll see the same behaviour.

 

[Sheila Jones]

Hello,

If you're using version 1.1 of the .Net framework, you can use the HasRows
property to test for this.

Hope that helps!