从 MySQL 中的多个表导出数据的最佳方法是什么。我基本上是在处理产品细节。假设一个产品有 150 个数据属性。我如何将其导出到一行中，然后将其导出到 CSV 或制表符格式的平面文件中。

获取错误表太多； MySQL一次连接只能使用61张表

/**** Get Resultset *****/
$rs = mysql_query($sql);
/**** End of Get Resultset *****/

$objProfileHistory->addHistory($this->profile_id, "Loaded ". mysql_num_rows($rs)." records");


$this->runQuery($sql);

$this->exportToCSV();

/**
  * getAttributeDetails
  */
function getAttributeDetails(){
    global $dbObj, $profile;

    $base_table = "catalog_product_entity";
    $select  = array();
    $tables  = array();
    $i   = 0;

    $profile->showLog("Start fields mapping", "success");

   if( is_array($this->attributes_in_db) && sizeof($this->attributes_in_db) > 0 ){
    $arr = implode("','", $this->attributes_in_db);
    $sql = "select attribute_id, attribute_code, backend_type, frontend_input
        from eav_attribute 
        where attribute_code in ('".$arr."') 
        and entity_type_id = 
         (select entity_type_id 
          from eav_entity_type 
          where entity_type_code = 'catalog_product')";
    $rs = $dbObj->customqry($sql);

    if( $rs ){
     while( $row = mysql_fetch_assoc( $rs ) ){
      $backend_type  = $row["backend_type"];
      $attribut_code = $row["attribute_code"];
      $attribute_id = $row["attribute_id"];
      $frontend_input = $row["frontend_input"];
      switch( $backend_type ){
       case "text":
        $where[]  = $base_table."_".$backend_type."".$i.".attribute_id=".$attribute_id;
        $and[]  = $base_table.".entity_id=".$base_table."_".$backend_type."".$i.".entity_id";
        $select[]  = $base_table."_".$backend_type."".$i.".value as ".$attribut_code;
        $tables[]  = $base_table."_".$backend_type." as ".$base_table."_".$backend_type."".$i;
       break;

       case "decimal":
        $where[]  = $base_table."_".$backend_type."".$i.".attribute_id=".$attribute_id;
        $and[]  = $base_table.".entity_id=".$base_table."_".$backend_type."".$i.".entity_id";
        $select[]  = $base_table."_".$backend_type."".$i.".value as ".$attribut_code;
        $tables[]  = $base_table."_".$backend_type." as ".$base_table."_".$backend_type."".$i;
       break;

       case "static":
        $where[]  = $base_table."".$i.".entity_id=".$base_table.".entity_id";
        $and[]  = $base_table.".entity_id=".$base_table."".$i.".entity_id";
        $select[]  = $base_table."".$i.".".$attribut_code." as ".$attribut_code;
        $tables[]  = $base_table." as ".$base_table."".$i;
       break;

       case "int":
        if( $attribut_code == "tax_class_id" && $frontend_input == "select" ){
         $where[]  = "tax_class{$i}.class_id=(select ".$base_table."_".$backend_type."".$i.".value from ".$base_table."_".$backend_type." as ".$base_table."_".$backend_type."".$i." where  ".$base_table."_".$backend_type."".$i.".attribute_id=".$attribute_id." and ".$base_table."_".$backend_type."".$i.".entity_id=".$base_table.".entity_id limit 1))";
         $and[]  = "";
         $select[]  = "tax_class{$i}.class_name as {$attribut_code}";
         $tables[]  = "tax_class as tax_class{$i}";
         } else if( $frontend_input == "select" ){
         $where[]  = "eav_attribute_option_value{$i}.option_id=(select ".$base_table."_".$backend_type."".$i.".value from ".$base_table."_".$backend_type." as ".$base_table."_".$backend_type."".$i." where  ".$base_table."_".$backend_type."".$i.".attribute_id=".$attribute_id." and ".$base_table."_".$backend_type."".$i.".entity_id=".$base_table.".entity_id limit 1))";
         $and[]  = "";
         $select[] = "eav_attribute_option_value{$i}.value as {$attribut_code}";
         $tables[]  = "eav_attribute_option_value as eav_attribute_option_value{$i}";
        } else {
         $where[]  = $base_table."_".$backend_type."".$i.".attribute_id=".$attribute_id;
         $and[]  = $base_table.".entity_id=".$base_table."_".$backend_type."".$i.".entity_id";
         $select[]  = $base_table."_".$backend_type."".$i.".value as ".$attribut_code;
         $tables[]  = $base_table."_".$backend_type." as ".$base_table."_".$backend_type."".$i;
        }
       break;

       case "varchar":
        $where[]  = $base_table."_".$backend_type."".$i.".attribute_id=".$attribute_id;
        $and[]  = $base_table.".entity_id=".$base_table."_".$backend_type."".$i.".entity_id";
        $select[]  = $base_table."_".$backend_type."".$i.".value as ".$attribut_code;
        $tables[]  = $base_table."_".$backend_type." as ".$base_table."_".$backend_type."".$i;
       break;

       case "datetime":
        $where[]  = $base_table."_".$backend_type."".$i.".attribute_id=".$attribute_id;
        $and[]  = $base_table.".entity_id=".$base_table."_".$backend_type."".$i.".entity_id";
        $select[]  = $base_table."_".$backend_type."".$i.".value as ".$attribut_code;
        $tables[]  = $base_table."_".$backend_type." as ".$base_table."_".$backend_type."".$i;
       break;
      }//switch
      $i++;
     }//while


     $sql = "select ".implode(",", $select)." from ".$base_table;
     for($i=0; $i < sizeof($select); $i++){
      $sql .= " left join ". $tables[$i] . " on (".$where[$i];//." and ".$and[$i].")";
      if( strlen($and[$i]) > 0 ){
       $sql .= " and ".$and[$i].")";
      }
     }//for
     $sql .= " group by {$base_table}.entity_id ";
    }//if
    //echo $sql; exit;
    return $sql;
   }
   //echo $sql;
   //echo "<pre>";print_r($tables);print_r($select);print_r($where);print_r($and);
  }//end function

  /**
  * runQuery
  */
  function runQuery( $sql ){
   global $dbObj, $profile;
   if( $sql != "" ){
    $rs = $dbObj->customqry( $sql );
    $profile->showLog("Loaded ". mysql_num_rows($rs) ." records", "success");
    if( $rs ){
     $i = 0;
     while( $row = mysql_fetch_assoc( $rs ) ){
      $cnt = sizeof($this->attributes_in_db);
      for($j=0; $j < $cnt; $j++){
       $db_key  = $this->attributes_in_db[$j];
       $file_key = $this->attributes_in_file[$j];
       $this->export_data[$i][$db_key] = $row[$db_key];
      }
      $i++;
     }//while
    }
   }//if
  }//end function


  /**
  * exportToCSV
  */
  function exportToCSV(){
   global $smarty, $objProfileHistory, $profile;
   //$newFileName = $smarty->root_dir."/export/".$this->filename; //file name that you want to create
   $cnt = sizeof($this->var_array);
   for($i=0; $i < $cnt; $i++){
    extract($this->var_array[$i]);
   }//for


   if( $delimiter = "\t" ){
    $delimiter = "\t";//$delimiter;
   }

   if( strlen($filename) < 1 ){
    $filename = time().".csv";
   }

//    echo "<pre>";
//    print_r($this->action_array);
//    print_r($this->var_array);
//    print_r($this->map_array);
//    exit;
   # add amazon headers
   if( $this->action_array[0]['type'] == 'header' ){
//     $template_type  = $this->var_array[0]['template_type'];
//     $version   = $this->var_array[0]['version'];
//     $status_message = $this->var_array[0]['status_message'];
    $sStr = "TemplateType=".$template_type."{$delimiter}{$delimiter}Version=".$version."{$delimiter}{$delimiter}{$status_message}";
    $sStr .= "� ��\n"; //to seprate every record
   }





   $export_path = $path;
   $x_path = $profile->createDir( $export_path );

   $newFileName = $x_path ."/". $filename;

   $fpWrite = fopen($newFileName, "w"); // open file as writable

   # create header
   $cnt_header = sizeof($this->attributes_in_file);
   for( $i=0; $i < $cnt_header; $i++){
    $sStr .= $deli . $this->attributes_in_file[$i];
    $deli = $delimiter;
   }//for
   $sStr .= "� ��\n"; //to seprate every record

   # attach data
   $cnt_row = sizeof($this->export_data);
   for( $i=0; $i < $cnt_row; $i++ ){
    $sStr .= $saperator;
    $newdeli = "";
    for($j=0; $j < $cnt_header; $j++){
     $key  = $this->attributes_in_db[$j];
     $sku = $this->export_data[$i]["sku"];

最佳答案

您正在使用 EAV 设计，并尝试从可变数量的属性中重新构建单行。这指出了您在使用 EAV 设计时会遇到的众多地雷之一:在单个 SQL 查询中可以进行的连接数量存在实际限制。

尤其是在 MySQL 中——如您所见，存在硬性限制。但即使在其他 RDBMS 品牌中，也存在有效限制，因为连接成本与表数量成几何关系。

如果您使用 EAV，不要尝试在 SQL 中重新构建行<​​ trong="">，就好像您有传统的数据库设计一样。相反，获取属性作为行，按实体 ID 排序。然后在您的应用程序代码中对它们进行后处理。这确实意味着您不能一步转储数据——您必须编写代码来循环遍历属性行，并在输出之前修改每一行数据。

EAV 不是一个方便的数据库设计。使用它有很多代价高昂的缺点，而您恰恰遇到了其中一个。

关于mysql - table 太多； MySQL 在一个连接中只能使用 61 个表，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/1684971/