php - 从表中删除列

Question

我有一个 .csv 文件数据正在导入到 mysql 表中。每次运行代码时，我喜欢做的就是删除所有列和数据并用更新的 .csv 内容替换它。

   $affectedRows = $pdo->exec("
     //HERE I do need additional code to drop column data from $databasetable similar to following
  /*------------------------------------------*/
    DROP TABLE IF EXISTS '$databasetable'

    CREATE TABLE IF NOT EXISTS `$databasetable` (
          Column names1
          Column name 2
          .
     ) ENGINE=MyISAM DEFAULT CHARSET=utf8;
  /*------------------------------------------*/


     LOAD DATA LOCAL INFILE ".$pdo->quote($csvfile)." INTO TABLE `$databasetable`
     FIELDS TERMINATED BY ".$pdo->quote($fieldseparator)."
     LINES TERMINATED BY ".$pdo->quote($lineseparator));

Answer 1

我认为您想要做的是截断有问题的表。那就是删除表中的所有数据，但不删除表本身，对吗？所以，这里有 1 个提示:

<?php 
    //FIRST TRUNCATE (REMOVE OLD DATA IN THE TABLE $databasetable
    $stmt      = $db->prepare("TRUNCATE TABLE {$databasetable}");
    $tblEmpty  = $stmt->execute();

    //NOW, ONCE THE TABLE'S BEEN TRUNCATED; YOU MAY CONTINUE WITH THE NEW "INSERTS"...
    if($tblEmpty){
        // INSERT THE DATA FROM THE CSV...
    }

    //...
    //...
    // MORE CODE HERE...