Check if a database cell is empty first

Question

I am accessing an MS Access 2007 database through C#, and I keep getting an exception whenever I try to read an empty cell.

Specifically, I am trying to read a "Date/Time" cell that may or may not be empty. I am using OLE DB, and have filled a DataSet. None of these conditions work:

DataSet dataSet = GetDataSet();
DataRow row = dataSet.Tables[0].Rows[0];
DateTime time = new DateTime();
time = (DateTime)row[5];   // Exception thrown

How to check if the cell is empty before trying to assign it? None of these work:

if(row[5] == null) ;
if(row[5] == DBNull) ;
if(row[5] == (String)"") ;

Edit: I should have mentioned: When I debug, it says that row[5] equals "System.DBNull,", but I get an error when I try "if(row[5] == DBNULL)". The error says "DBNULL is a type, which is not valid in the given context".

"cell" is what you reference in a spreadsheet; it's a specific column in a record when dealing with a database. — OMG Ponies, Dec 10 '10 at 05:41

score 11 · Accepted Answer · edited Feb 17 '11 at 21:04

11

You can check it like the following.

if (row[5] == DBNull.Value)
{
    // value is null
}
else if (String.IsNullOfEmpty(Convert.ToString(row[5]))
{
    // value is still null
}
else
{
    // value is not null here
}

edited Feb 17 '11 at 21:04

Peter Mortensen

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answered Dec 10 '10 at 05:47

Zain Shaikh

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Thanks, that's it. I didn't put the ".Value" after DBNULL. – Eric Dec 10 '10 at 05:50

score 3 · Answer 2 · answered Dec 10 '10 at 05:47

3

if(row[5] == DBNull.Value)

answered Dec 10 '10 at 05:47

TalentTuner

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5
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Thanks. That's it. Forgot the ".Value" – Eric Dec 10 '10 at 05:51

score 0 · Answer 3 · edited Feb 15 '18 at 15:21

0

if(Convert.IsDBNull(row[5]))
{
...
}

edited Feb 15 '18 at 15:21

Liam

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answered Feb 15 '18 at 14:15

Ilaria

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Check if a database cell is empty first

3 Answers3

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