Question

I did my homework prior to asking this questions. Though, none of the results that google showed functioned .

I have a textbox whose input I wish to validate against a list of values which exist in a column of a table (ASP.NET with C# and SQL Server 2014 Express) . Should user enter some other value, than the error must be displayed.

I have done multiple tryouts with CustomValidator control and one when an event on the Textbox (.TextChanged). But I lost something, may be in the details. Could you give me a practical solution and at best, guide towards a useful online resource to study the connection to databases from asp.net (c#)?

I am aware that I did not catch the subject.

Answer 1

Here is a basic rough version how you could get it done. Can also use a Stored procedure rather than direct..Wasn't sure if you meant after a button was clicked or not, but you can put this in a method and have it return true or false if its valid.

        SqlConnection cnn = null;
        SqlCommand cmd = null;
        SqlDataAdapter sda = null;
        DataTable Dt = new Datatable();

        cnn = new SqlConnection(strConnectionString);
        cmd = new SqlCommand("Select COLUMN FROM WHEREVER WHERE VALUE =@TextboxValue", cnn);
        cnn.Open();
        cmd.CommandType = CommandType.Text;
        cmd.Parameters.Add("@TextboxValue", SqlDbType.VarChar).Value = Textbox.Text;
        sda = new SqlDataAdapter(cmd);
        sda.Fill(dt);

       if (dt.rows.count > 0 ) 
        {
           //MATCH FOUND
        }

how do I validate a user input in a Textbox against a column from a SQL Server table

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