Delete a row from a SQL Server table

Question

I m trying to simply delete a full row from my SQL Server database table using a button event  So far none of my attempts have succeeded  This is what I m trying to do   public static void deleteRow string table  string columnName  string IDNumber        try           using  SqlConnection con   new SqlConnection Global connectionString                  con Open             using  SqlCommand command   new SqlCommand  DELETE FROM     table     WHERE     columnName           IDNumber  con                             command ExecuteNonQuery                        con Close                    catch  SystemException ex                  MessageBox Show string Format  An error occurred   0    ex Message                       I keep receiving the error       A first chance exception of type  System Data SqlClient SqlException  occurred in System Data dll   An error occurred  Operand type clash  text is incompatible with int   All of the columns in the table are of TEXT type  Why cannot I compare the function argument of type string to the columns to find the match   And then delete the row

User · Answer

private void DeleteProductButton Click object sender  EventArgs e          string ProductID   deleteProductButton Text      if  string IsNullOrEmpty ProductID                 MessageBox Show  Please enter valid ProductID            deleteProductButton Focus              try               string SelectDelete    Delete from Products where ProductID     deleteProductButton Text          SqlCommand command   new SqlCommand SelectDelete  Conn           command CommandType   CommandType Text          command CommandTimeout   15           DialogResult comfirmDelete   MessageBox Show  Are you sure you want to delete this record             if  comfirmDelete    DialogResult No                        return                      catch  Exception Ex                MessageBox Show Ex Message

User · Answer

As you have stated that all column names are of TEXT type  So  there is need to use IDNumber as Text by using single quote around IDNumber           public static void deleteRow string table  string columnName  string IDNumber            try           using  SqlConnection con   new SqlConnection Global connectionString                  con Open             using  SqlCommand command   new SqlCommand  DELETE FROM     table     WHERE     columnName            IDNumber      con                             command ExecuteNonQuery                        con Close                    catch  SystemException ex                  MessageBox Show string Format  An error occurred   0    ex Message

User · Answer

If you are using MySql Wamp  This code work   string con  SERVER localhost  user id root  password   database dbname   public void delete     try   MySqlConnection connect   new MySqlConnection con   MySqlDataAdapter da   new MySqlDataAdapter    connect Open    da DeleteCommand   new MySqlCommand  DELETE FROM table WHERE ID      ID Text        connect   da DeleteCommand ExecuteNonQuery     MessageBox Show  Successfully Deleted      catch Exception e    MessageBox Show e Message

User · Answer

private void button4 Click object sender  EventArgs e        String st    DELETE FROM supplier WHERE supplier id      textBox1 Text       SqlCommand sqlcom   new SqlCommand st  myConnection       try               sqlcom ExecuteNonQuery            MessageBox Show  delete successful              catch  SqlException ex                MessageBox Show ex Message              private void button6 Click object sender  EventArgs e        String st    SELECT   FROM suppliers        SqlCommand sqlcom   new SqlCommand st  myConnection       try               sqlcom ExecuteNonQuery            SqlDataReader reader   sqlcom ExecuteReader            DataTable datatable   new DataTable            datatable Load reader           dataGridView1 DataSource   datatable            catch  SqlException ex                MessageBox Show ex Message

User · Answer

Either IDNumber should be an int instead of a string  or if it s really a string  add quotes   Better yet  use parameters

User · Answer

Looks like IDNumber is a string   It needs single quote wrapped around it    DELETE FROM     table     WHERE     columnName            IDNumber

User · Answer

Try with paramter                                                   using  SqlCommand command   new SqlCommand  DELETE FROM     table     WHERE     columnName            IDNumber  con                                     command Paramter Add   IDNumber  IDNumber                     command ExecuteNonQuery                                                                  No need to close connection in using statement

User · Answer

You may change the  columnName  type from TEXT to VARCHAR MAX   TEXT column can t be used with      see this topic

[c#] Delete a row from a SQL Server table

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