How to count the no of rows in a table?

Question

0.00/5 (No votes)

See more:

How can we count the number of rows in a table?

C#

string dbcnstr = @"Data Source=.\SQLEXPRESS;AttachDbFilename=path.mdf;Integrated Security=True;User Instance=True";
            
SqlConnection conn = new SqlConnection(dbcnstr);
conn.Open();
       
DataSet ds = new DataSet();
int c = ds.Tables["pic"].Rows.Count;
MessageBox.Show("pic table contains "+ c+" no of rows");
conn.Close();

This doesn't work properly. Please can any one help me?

Posted 31-May-11 8:15am

Member 7779792

Updated 31-May-11 8:37am

Sandeep Mewara

v3

Add a Solution

3 solutions

Solution 1

Well, you could try putting some data in the table...

"table is already containing data."

DataSet ds = new DataSet();
int c = ds.Tables["pic"].Rows.Count;

Since when?

Posted 31-May-11 8:24am

OriginalGriff

Updated 31-May-11 8:44am

v2

Comments

Member 7779792 31-May-11 14:29pm

table is already containing data.

OriginalGriff 31-May-11 14:44pm

Answer updated

Solution 3

You know, instead of using a DataSet to read an entire table just to get the number of rows, one could ask the database for just the rowcount directly:

C#

string dbcnstr = @"Data Source=.\SQLEXPRESS;AttachDbFilename=path.mdf;Integrated Security=True;User Instance=True";
            
SqlConnection conn = new SqlConnection(dbcnstr);
conn.Open();
       
SqlCommand getRowCount = new SqlCommand("SELECT COUNT(*) FROM pic", conn);
int c = (int)getRowCount.ExecuteScalar();

MessageBox.Show("pic table contains "+ c+" no of rows");
conn.Close();

Of course, this code assumes that you only want to get the number of rows, and not do anything else with the data in your DataSet. If that's not the case then just ignore this answer :)

Posted 31-May-11 9:42am

R. Hoffmann

Add a Solution

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

R. Hoffmann · Accepted Answer · 2011-05-31T08:27:00

Solution 2

It looks like you're referring to a table that doesn't exist in the DataSet yet ("pic"). The code you provided creates an empty DataSet, and then tries to access a specific table that simply isn't there.

You'll have to populate the DataSet somehow, perhaps by using a DataAdapter, before trying to access its contents.

I'm guessing that this is what you mean by "this doesn't work properly." If not, please reply to this answer, and provide any error messages or exceptions you're getting, or add them to your original question. Thanks.

Posted 31-May-11 8:27am

R. Hoffmann

Comments

Member 7779792 31-May-11 14:42pm

it runs a NullReference Exception. the message says "object reference is not set to an object".
what should i do to correct it?please help me!!! any suggestions?

R. Hoffmann 31-May-11 14:56pm

This will be because your DataSet is empty - the part that says "ds.Tables["pic"]" returns a null because the "pic" table doesn't exist, and when you then call ".Rows" on it, it throws an exception.

You must understand that a DataSet is simply a container for data, it isn't capable of getting the data by itself. You need to add code to read data from the database connection you instantiated and put it into the DataSet, between where you create the Dataset and where you try to get the rowcount, for this to work. Your existing code is good, it is just a little incomplete.

R. Hoffmann 31-May-11 14:58pm

And when I say "the pic table doesn't exist", I mean it doesn't exist in the DataSet. It may exist in your actual database, but as I said, the DataSet doesn't know that, it's simply a "dumb" container for data.

Member 7779792 31-May-11 15:40pm

i include the DataAdapter.now it executes as i expected.thank you very much for your help!i appreciate your help a lot! thank you so much.

R. Hoffmann 31-May-11 15:44pm

I'm happy to have been of service :)

How to count the no of rows in a table?

3 solutions

Solution 2

Solution 1

Solution 3

Add your solution here

Preview 0

How to count the no of rows in a table?

3 solutions

Solution 2

Solution 1

Solution 3

Add your solution here

Preview 0

Existing Members

...or Join us