sql去重，备份表惯用sql等

sql去重，备份表常用sql等

1:SELECT INTO 和 INSERT INTO SELECT 两种表复制语句

转至http://www.cnblogs.com/freshman0216/archive/2008/08/15/1268316.html

?

Insert是T-sql中常用语句，Insert INTO table(field1,field2,...) values(value1,value2,...)这种形式的在应用程序开发中必不可少。但我们在开发、测试过程中，经常会遇到需要表复制的情况，如将一个table1的数据的部分字段复制到table2中，或者将整个table1复制到table2中，这时候我们就要使用SELECT INTO 和 INSERT INTO SELECT 表复制语句了。

????? 1.INSERT INTO SELECT语句

??????语句形式为：Insert into Table2(field1,field2,...) select value1,value2,... from Table1

????? 要求目标表Table2必须存在，由于目标表Table2已经存在，所以我们除了插入源表Table1的字段外，还可以插入常量。示例如下：

SELECT INTO FROM创建表并复制表数据
<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />-->???--1.创建测试表
????create?TABLE?Table1
????(
????????a?varchar(10),
????????b?varchar(10),
????????c?varchar(10),
????????CONSTRAINT?[PK_Table1]?PRIMARY?KEY?CLUSTERED
????????(
????????????a?ASC
????????)
????)?ON?[PRIMARY]
????GO

????--2.创建测试数据
????Insert?into?Table1?values('赵','asds','90')
????Insert?into?Table1?values('钱','asds','100')
????Insert?into?Table1?values('孙','asds','80')
????Insert?into?Table1?values('李','asds',null)
????GO

????--3.SELECT?INTO?FROM语句创建表Table2并复制数据
????select?a,c?INTO?Table2?from?Table1
????GO

????--4.显示更新后的结果
????select?*?from?Table2
????GO
????--5.删除测试表
????drop?TABLE?Table1
????drop?TABLE?Table22:自己总结的sql去重

--author:陈超

--查询是否有template_id重复的模板(comframe里)
select template_id,count(template_id) from vm_template vt group by template_id having count(8)>1;

--查出所有重复的数据
SELECT ROWID,NCA.CLASS_NAME FROM NG_CFG_AUDIT NCA WHERE NCA.CLASS_NAME IN
(SELECT NCA2.CLASS_NAME FROM NG_CFG_AUDIT NCA2 GROUP BY NCA2.CLASS_NAME HAVING COUNT(*)>1);

--查询多余的数据的rowid最大的一条
SELECT MAX(NCA3.ROWID),NCA3.CLASS_NAME FROM NG_CFG_AUDIT NCA3 GROUP BY NCA3.CLASS_NAME HAVING COUNT(*)>1;

--查询多出来的数据
(
SELECT NCA.ROWID,NCA.CLASS_NAME FROM NG_CFG_AUDIT NCA WHERE NCA.CLASS_NAME IN
(SELECT NCA2.CLASS_NAME FROM NG_CFG_AUDIT NCA2 GROUP BY NCA2.CLASS_NAME HAVING COUNT(*)>1)
)
MINUS
(
SELECT MAX(NCA3.ROWID),NCA3.CLASS_NAME FROM NG_CFG_AUDIT NCA3 GROUP BY NCA3.CLASS_NAME HAVING COUNT(*)>1
);

--删除多余的数据(对于多的只保留一条)
DELETE? FROM NG_CFG_AUDIT NCA4 WHERE NCA4.ROWID IN(
(
SELECT NCA.ROWID FROM NG_CFG_AUDIT NCA WHERE NCA.CLASS_NAME IN
(SELECT NCA2.CLASS_NAME FROM NG_CFG_AUDIT NCA2 GROUP BY NCA2.CLASS_NAME HAVING COUNT(*)>1)
)
MINUS
(
SELECT MAX(NCA3.ROWID) FROM NG_CFG_AUDIT NCA3 GROUP BY NCA3.CLASS_NAME HAVING COUNT(*)>1
)
);

SELECT ROWID,NCA.* FROM NG_CFG_AUDIT NCA WHERE NCA.CLASS_NAME='com.asiainfo.boss.channel.ng.channelinfo.service.impl.PopularizeCostDrawInfoSVImpl';
注：如果多个字段联合唯一去重，则可以用||将它们连接起来in操作

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