我有一个表与以下字段:

id (Unique)
url (Unique)
title
company
site_id

现在,我需要删除具有相同标题、company和site_id的行。一种方法是使用下面的SQL和脚本(PHP):

SELECT title, site_id, location, id, count( * ) 
FROM jobs
GROUP BY site_id, company, title, location
HAVING count( * ) >1

运行此查询后,可以使用服务器端脚本删除重复项。

但是,我想知道这是否只能使用SQL查询。


当前回答

我找到了一个简单的方法。(保持最新的)

DELETE t1 FROM table_name t1 INNER JOIN table_name t2 
WHERE t1.primary_id < t2.primary_id 
AND t1.check_duplicate_col_1 = t2.check_duplicate_col_1 
AND t1.check_duplicate_col_2 = t2.check_duplicate_col_2
...

其他回答

如果您试图删除其中一个副本并保留另一个副本,那么这是完美的。注意,如果没有子查询,您将得到#1093错误。

DELETE FROM table_name
WHERE id IN (
    SELECT * FROM (SELECT n.id FROM table_name n
    WHERE n.column2 != "value"
    GROUP BY n.column HAVING COUNT(n.column ) > 1) x
)

还有另一种解决方案:

DELETE t1 FROM my_table t1, my_table t2 WHERE t1.id < t2.id AND t1.my_field = t2.my_field AND t1.my_field_2 = t2.my_field_2 AND ...

你可以很容易地从这个代码中删除重复的记录。

$qry = mysql_query("SELECT * from cities");
while($qry_row = mysql_fetch_array($qry))
{
$qry2 = mysql_query("SELECT * from cities2 where city = '".$qry_row['city']."'");

if(mysql_num_rows($qry2) > 1){
    while($row = mysql_fetch_array($qry2)){
        $city_arry[] = $row;

        }

    $total = sizeof($city_arry) - 1;
        for($i=1; $i<=$total; $i++){


            mysql_query( "delete from cities2 where town_id = '".$city_arry[$i][0]."'");

            }
    }
    //exit;
}

如果IGNORE语句在我的例子中不起作用,你可以使用下面的语句:

CREATE TABLE your_table_deduped LIKE your_table;


INSERT your_table_deduped
SELECT *
FROM your_table
GROUP BY index1_id,
         index2_id;

RENAME TABLE your_table TO your_table_with_dupes;

RENAME TABLE your_table_deduped TO your_table;

#OPTIONAL
ALTER TABLE `your_table` ADD UNIQUE `unique_index` (`index1_id`, `index2_id`);

#OPTIONAL
DROP TABLE your_table_with_dupes;

我找到了一个简单的方法。(保持最新的)

DELETE t1 FROM table_name t1 INNER JOIN table_name t2 
WHERE t1.primary_id < t2.primary_id 
AND t1.check_duplicate_col_1 = t2.check_duplicate_col_1 
AND t1.check_duplicate_col_2 = t2.check_duplicate_col_2
...