如何使用 java 和 mysql 计算表中的所有行

Question

I want to Count all the rows in the table using java and display the count of all the rows in the textfield. I need the count of employee from the table. I have attached below the code and the query used to achieve this. I received the error of the below code Column 'id' not found. error displayed

public void Customer()
{
    try {
         pst = con.prepareStatement("SELECT COUNT(*) FROM customer");
         ResultSet rs = pst.executeQuery(); 
         while(rs.next())
         {
         String id1 = rs.getString("id");
            txtmsg.setText(id1);
         } 
    } catch (SQLException ex) {
        Logger.getLogger(gsm.class.getName()).log(Level.SEVERE, null, ex);
    }
}

Answer 1

There clearly is no "id" column in your select. You could either get the result by column number like so:

int count = rs.getInt(1);

Or you could use an alias for the column and get result by that name, eg.:

pst = con.prepareStatement("SELECT COUNT(*) AS customerCount FROM customer");
int count = rs.getInt("customerCount");