2017年計(jì)算機(jī)等考三級(jí)數(shù)據(jù)庫(kù)SQL語(yǔ)句整理

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1、說(shuō)明:創(chuàng)建數(shù)據(jù)庫(kù) CREATE DATABASE database-name 2、說(shuō)明:刪除數(shù)據(jù)庫(kù) drop database dbname 3、說(shuō)明:備份sql server --- 創(chuàng)建 備份數(shù)據(jù)的 device USE master EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' --- 開(kāi)始 備份 BACKUP DATABASE pubs TO testBack 4、說(shuō)明:創(chuàng)建新表 create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) 根據(jù)已有的表創(chuàng)建新表: A:create table tab_new like tab_old (使用舊表創(chuàng)建新表) B:create table tab_new as select col1,col2… from tab_old definition only 5、說(shuō)明:刪除新表 drop table tabname 6、說(shuō)明:增加一個(gè)列 Alter table tabname add column col type 注:列增加后將不能刪除。DB2中列加上后數(shù)據(jù)類(lèi)型也不能改變,能改變的是增加varchar類(lèi)型的長(zhǎng)度。 7、說(shuō)明:添加主鍵: Alter table tabname add primary key(col) 說(shuō)明:刪除主鍵: Alter table tabname drop primary key(col) 8、說(shuō)明:創(chuàng)建索引:create [unique] index idxname on tabname(col….) 刪除索引:drop index idxname 注:索引是不可更改的,想更改必須刪除重新建。 9、說(shuō)明:創(chuàng)建視圖:create view viewname as select statement 刪除視圖:drop view viewname 10、說(shuō)明:幾個(gè)簡(jiǎn)單的基本的sql語(yǔ)句 選擇:select * from table1 where 范圍 插入:insert into table1(field1,field2) values(value1,value2) 刪除:delete from table1 where 范圍 更新:update table1 set field1=value1 where 范圍 查找:select * from table1 where field1 like ’%value1%’ ---like的語(yǔ)法很精妙,查資料! 排序:select * from table1 order by field1,field2 [desc] 總數(shù):select count as totalcount from table1 求和:select sum(field1) as sumvalue from table1 平均:select avg(field1) as avgvalue from table1 :select max(field1) as maxvalue from table1 最?。簊elect min(field1) as minvalue from table1