加速 SQL 更新循环通过 Select 语句的语句

Question

发现代码中的 SQL 查询需要 31 分钟（1900 秒）才能完成。首先 select 语句获取 1955 行，然后代码循环遍历这些行以运行根据该记录集中的数字进行更新。它运行通过的 table 有 14,000 行。我怎样才能加快速度？

$sql = "select id, did, customer_id from dids";
        $rs = $db->PDOquery($sql, $qry_arr);
        //Loop through all DIDs and attach to cdrs  select id, did, customer_id from dids   
        while($row=$rs->fetch()){                           
            $qry_arr = array(':did_id' => $row['id'],
                        ':customer_id' => $row['customer_id'],
                        ':did' => $row['did']);
            $sql = "update ".$billing_table."  c ";
            $sql .= "set c.did_id = :did_id, c.customer_id = :customer_id  ";
            $sql .= "where c.customer_id = 0 and c.telcom_num = :did ";

            $result=$db->PDOquery($sql, $qry_arr);
            set_time_limit(30);  //Reset time limit after each query
            if (!$result) {
                error_log(date("Y/m/d h:i:sa").": "."\nError In Sql.\n".$sql, 3, $cron_log);
            }
        }

尝试使用以下方法，但收到错误消息：错误代码：1054。'where clause'

中的未知列 'dids.did'

 UPDATE ".billing_table." SET ".billing_table.".did_id = dids.id, ".billing_table.".customer_id = dids.customer_id WHERE dids.did =  ".billing_table.".telcom_num

Answer 1

序列化 SQL 查询通常会导致性能不佳。您可以在一条语句中完成所有操作：

$sql = "update ".$billing_table." c ".
       "inner join dids d on d.did=c.telcom_num ".
       "set c.did_id = d.id, c.customer_id = d.customer_id ".
       "where c.customer_id = 0;";

加速 SQL 更新循环通过 Select 语句的语句

Speed Up SQL Update Statement That Is Looped Through A Select Statement

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