How can I know if such value exists in database? (ADO.NET)

Question

For example, I have a table, and there is a column named 'Tags'. I want to know if value 'programming' exists in this column. How can I do this in ADO.NET?

I did this:

OleDbCommand cmd = new OleDbCommand("SELECT * FROM table1 WHERE Tags='programming'", conn);
OleDbDataReader = cmd.ExecuteReader();

What should I do next?

Answer 1

use SELECT COUNT(*) and check the results. (and use ExecuteScalar)

(assuming you know how to set the connection and use it)

Answer 2

SELECT  TOP 1 1
FROM    table1
WHERE   Tags='programming'

Answer 3

better version, it is a good practice to use parameters instead of string concatenation, see sql injection

OleDbCommand cmd = new OleDbCommand("SELECT TOP 1 1
 FROM table1 WHERE Tags=?", conn);
cmd.Parameters.Add("@p1", OleDbType.VarChar).Value = "Programming";
OleDbDataReader rdr = cmd.ExecuteReader();
if(rdr.Read())
    // record exists
else
   //Not exists

Answer 4

You should do two things:

If you are just checking the presence of a tag called Programming, you should change your query to return a COUNT instead of returning all rows.

SELECT TOP 1 Column1 FROM Table1 WHERE Tags = 'Programming'

You should check the returned set in the reader to see if there are any rows. If there are, then it means that the tag exists.