创建表格后，它将显示此数组([0] => 00000 [1] => [2] =>) [英] After creating table it shows this Array ( [0] => 00000 [1] => [2] => )

问题描述

在PDO中使用exec()创建表后，它显示如下

After creating table using exec() in PDO,it shows like this

Array ( [0] => 00000 [1] => [2] => )

这是错误还是我成功创建了表格? 当我在数据库中查找表时，就会创建表.

Is this an error or did I successfully create my table? When I looked up in the database the table is created.

这就是我执行的

try{

    $tbl = new PDO("mysql:host=localhost;dbname=myDB",'root',''); 
     $tbl->exec("CREATE TABLE test(fld1 CHAR(40),fld2 CHAR(40))")
     or die(print_r($tbl->errorInfo(),true));
   }
catch(Exception $e){
     echo $e.getMessage();
 } 

@Vikas，如果我错了，请纠正我.这可以正常工作

@Vikas,correct me if i am wrong.and this is working

    $queryTBl="CREATE TABLE test(fld1 CHAR(40),fld2 CHAR(40))";

    $evaluateTBL=tbl->exec($queryTBL);

    if ($evaluateTBL===false)
         print "Test table could not be created";
    else
         print "Successfully Created";

推荐答案

根据 PDO :: exec manual ，它返回受查询影响的行数.而且没有任何行受CREATE查询影响.因此，此查询的exec即使成功也将返回0.它将被评估为false.这就解释了为什么即使没有错误也要调用die的原因.

According to PDO::exec manual it returns number of rows affected by the query. And there is no rows affected by a CREATE query. So exec for this query will return 0 even if it was successful. And it will be evaluated false. This explains why die is called even when there is no error.

最好依靠异常或对exec的返回码进行=== false以确定它是否失败.从手册中:

It is better to either rely on exception or do a === false on return code of exec to decide if it failed. From the manual:

此函数可以返回布尔FALSE，但也可以返回非布尔值，其值为FALSE.请阅读有关布尔值的部分以了解更多信息.使用===运算符测试此函数的返回值.

This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.

执行相同操作的示例，但有例外:

Example of doing the same thing with exceptions:

try {
  $connection = new PDO("mysql:host=localhost;dbname=myDB",'root','');
  $connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

  $connection->exec('CREATE TABLE test(fld1 CHAR(40),fld2 CHAR(40))');
} catch (PDOException $e) {
  <handle exception>
}

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