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
简单和快速的所有情况:
CREATE TEMPORARY TABLE IF NOT EXISTS _temp_duplicates AS (SELECT dub.id FROM table_with_duplications dub GROUP BY dub.field_must_be_uniq_1, dub.field_must_be_uniq_2 HAVING COUNT(*) > 1);
DELETE FROM table_with_duplications WHERE id IN (SELECT id FROM _temp_duplicates);
其他回答
我一直在访问这个页面，任何时候我谷歌“从mysql中删除重复”，但对于我的忽略解决方案不起作用，因为我有一个InnoDB mysql表
这段代码在任何时候都能更好地工作
CREATE TABLE tableToclean_temp LIKE tableToclean;
ALTER TABLE tableToclean_temp ADD UNIQUE INDEX (fontsinuse_id);
INSERT IGNORE INTO tableToclean_temp SELECT * FROM tableToclean;
DROP TABLE tableToclean;
RENAME TABLE tableToclean_temp TO tableToclean;
tableToclean =需要清理的表的名称
tableToclean_temp =创建和删除的临时表
这个解决方案将把重复的数据移到一个表中，唯一的数据移到另一个表中。
-- speed up creating uniques table if dealing with many rows
CREATE INDEX temp_idx ON jobs(site_id, company, title, location);
-- create the table with unique rows
INSERT jobs_uniques SELECT * FROM
(
SELECT *
FROM jobs
GROUP BY site_id, company, title, location
HAVING count(1) > 1
UNION
SELECT *
FROM jobs
GROUP BY site_id, company, title, location
HAVING count(1) = 1
) x
-- create the table with duplicate rows
INSERT jobs_dupes
SELECT *
FROM jobs
WHERE id NOT IN
(SELECT id FROM jobs_uniques)
-- confirm the difference between uniques and dupes tables
SELECT COUNT(1)
AS jobs,
(SELECT COUNT(1) FROM jobs_dupes) + (SELECT COUNT(1) FROM jobs_uniques)
AS sum
FROM jobs
简单和快速的所有情况:
CREATE TEMPORARY TABLE IF NOT EXISTS _temp_duplicates AS (SELECT dub.id FROM table_with_duplications dub GROUP BY dub.field_must_be_uniq_1, dub.field_must_be_uniq_2 HAVING COUNT(*) > 1);
DELETE FROM table_with_duplications WHERE id IN (SELECT id FROM _temp_duplicates);
为了复制具有唯一列的记录，例如COL1,COL2, COL3不应该被复制(假设我们在表结构中遗漏了3个唯一列，并且在表中添加了多个重复项)
DROP TABLE TABLE_NAME_copy;
CREATE TABLE TABLE_NAME_copy LIKE TABLE_NAME;
INSERT INTO TABLE_NAME_copy
SELECT * FROM TABLE_NAME
GROUP BY COLUMN1, COLUMN2, COLUMN3;
DROP TABLE TABLE_NAME;
ALTER TABLE TABLE_NAME_copy RENAME TO TABLE_NAME;
希望将有助于开发。
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;
}
