mysql删除重复数据
删除表内重复数据的一种解决方案:
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Create Table: CREATE TABLE `tt` (
? `id` int(11) DEFAULT NULL,
? `name` varchar(30) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
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200万的数据
100万 id从1到100w name是zz
100条 id从1到100 name是zz
100万 id从1到100w name是mike
100条 id从1到100 name是mike
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存储过程:
新增sizes+1条数据,name为paramsCREATE PROCEDURE pro_insert2(in sizes int,in params varchar(30))begindeclare i int;start transaction;set i = 0;while i<=sizes doinsert into tt values(i,params);set i=i+1;end while;commit;endmysql> select count(*) from tt;
+----------+
| count(*) |
+----------+
| ?2000204 |
+----------+
1 row in set (0.00 sec)
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Create Table: CREATE TABLE `tt2` (
? `id` int(11) DEFAULT NULL,
? `name` varchar(30) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)
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mysql> insert into tt2 (select distinct * from tt);
Query OK, 2000002 rows affected (51.55 sec)
Records: 2000002 ?Duplicates: 0 ?Warnings: 0
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mysql> drop table tt;
Query OK, 0 rows affected (0.10 sec)
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mysql> alter table tt2 rename tt;
Query OK, 0 rows affected (0.09 sec)
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mysql> select count(*) from tt;
+----------+
| count(*) |
+----------+
| ?2000002 |
+----------+
1 row in set (2.54 sec)
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到此OK,这种方法效率不是很高,期待更有效率的方法