我有一个varchar列的表,我想找到在这个列中有重复值的所有记录。我可以使用什么查询来查找重复项?
当前回答
我从下面开始改进:
SELECT
col,
COUNT(col)
FROM
table_name
GROUP BY col
HAVING COUNT(col) > 1;
其他回答
进一步采取@maxyfc的答案,我需要找到所有返回的重复值的行,这样我就可以在MySQL Workbench中编辑它们:
SELECT * FROM table
WHERE field IN (
SELECT field FROM table GROUP BY field HAVING count(*) > 1
) ORDER BY field
下面的代码将找到所有使用了不止一次的product_id。每个product_id只能得到一条记录。
SELECT product_id FROM oc_product_reward GROUP BY product_id HAVING count( product_id ) >1
代码取自:http://chandreshrana.blogspot.in/2014/12/find-duplicate-records-based-on-any.html
我看到上面的结果和查询将工作良好,如果你需要检查单列值是重复的。比如电子邮件。
但如果你需要检查更多的列,并希望检查结果的组合,那么这个查询将正常工作:
SELECT COUNT(CONCAT(name,email)) AS tot,
name,
email
FROM users
GROUP BY CONCAT(name,email)
HAVING tot>1 (This query will SHOW the USER list which ARE greater THAN 1
AND also COUNT)
我从下面开始改进:
SELECT
col,
COUNT(col)
FROM
table_name
GROUP BY col
HAVING COUNT(col) > 1;
如果你想删除重复使用DISTINCT
否则使用这个查询:
SELECT users.*,COUNT(user_ID) as user FROM users GROUP BY user_name有用户>