Locid country city
39409 US Aaronsburg
128426 US Aaronsburg
340356 US Aaronsburg
429373 US Aaronsburg
422717 US Abbeville
431344 US Abbeville
433062 US Abbeville
341726 US Abbeville
421248 US Abbeville
40779 US Abbeville
326718 US Abbeville
317654 US Abbeville
16707 US Abbeville
25771 US Abbeville
120301 US Abbeville
132115 US Abbeville
121770 US Abbeville
130397 US Abbeville
5585 US Abbeville
10227 US Abbeville
190173 US Abbeville
491120 US Abbeville
311174 US Abbeville
306532 US Abbeville
164271 US Abbot
465218 US Abbot
58452 US Abbotsford
359399 US Abbotsford
309116 US Abbotsford
8169 US Abbotsford
有人可以给我一个SQL查询来帮我清理这个表吗?
清理Locid(索引)之后应该重置,顺便说一下这是一个县城使用这个查询SELECT Locid,country,city FROM location WHERE country =’US’ORDER BY city ASC.当我通过PHPmyadmin的导入多次导入sql文本时出现这个冗余数据,这就是结果,
解决方法:
在表位置添加唯一索引,以便不会插入重复的记录
ALTER IGnorE TABLE location ADD UNIQUE KEY ix1(country, city);
这将自动从表中删除重复记录,并且对于将来的插入查询,您需要使用INSERT IGnorE子句以避免出现重复错误.
但正如@ AD7six在评论中所建议的,它可能不适用于MysqL版本5.1.41,5.5.1-m2,6.0:请参阅错误here
DELETE a
FROM location a
LEFT JOIN (
SELECT Locid
FROM location
GROUP BY country, city
)b
ON a.Locid = b.Locid
WHERE b.Locid IS NULL;
要重置auto_increment列Locid的值,您只需将主键放在Locid上并重新创建它:
ALTER TABLE location DROP column Locid;
ALTER TABLE location
ADD COLUMN Locid INT unsigned NOT NULL AUTO_INCREMENT PRIMARY KEY FirsT;
SET var_Locid = 0;
UPDATE location
SET Locid = (@var_Locid := @var_Locid + 1)
ORDER BY Locid ASC;