PHP代码返回未知列错误

Question

I wonder if any PHP/MySQL experts out there can help me. I have written a PHP code which I am hoping will add new columns to my table in a database. Here is the following code:

     <?php

              // All the database connection codes here

      $retro = mysqli_real_escape_string($con, $_POST['retro']);
      $moon = mysqli_real_escape_string($con, $_POST['moon']);
      $astronomicalunit = mysqli_real_escape_string($con, $_POST['astronomicalunit']);

      $sql = "ALTER TABLE Planets
      ADD (COLUMN 'RetrogradePrograde' VARCHAR(45),
      COLUMN 'NumberOfMoons' VARCHAR(45),
      COLUMN 'DistanceFromSun' SMALLINT(5));";

      $sql = "UPDATE Planets
      SET   RetrogradePrograde = '$retro',
      NumberOfMoons = '$moon',
      DistanceFromSun = '$astronomicalunit';";

      // all the mysqli connection failure notification here

      // close mysqli connection

      ?>

But when I try to run this program on my browser, I get the message "Error: Unknown column 'RetrogradePrograde' in 'field list'" How can there be an UNKNOWN column when I have just created it? Please help.

Answer 1

Remove the column from the definition. Try this:-

$sql = "ALTER TABLE Planets
      ADD COLUMN(RetrogradePrograde VARCHAR(45),
      NumberOfMoons VARCHAR(45),
      DistanceFromSun SMALLINT(5));";