C与sqlserver数据库操作附实例说明及sql语句大全

1、成功信息网C#数据库连接操作大全+sql语句大全下面是c#与数据库的连接及增删改除的各种操作，全部经过上机验证。学习软件的过程中， 数据库起着至关重要的作用。软件行业里面有句老话，不会数据库就没有入门。软件思想可以慢慢培养，但是数据库的链接是一定要学会的。增删改查各种都不能少。创建数据库创建之前判断该数据库是否存在 if exists (select * from sysdatabases where n ame='databaseName') drop database 'databaseName' go Create DATABASE database-na

2、me删除数据库drop database dbn ame备份 sql server-创建 备份数据的 device USE master EXEC sp_addumpdevice 'disk', 'testBack', 'c:mssql7backupMyNwind_1.dat' -开始 备份 BACKUP DATABASE pubs TO testBack创建新表create table tab name(col1 type1 not n ull primary key,col2 type2 not null,.)根据已有的表创建新表：A: cr

3、eate table tab_new like tab_old (使用旧表创建新表) B : create table tab_new as select col1,col2from tab_olddefinition only 删除新表drop table tab name增加一个列Alter table tab name add colu mn col type注：列增加后将不能删除。DB2中列加上后数据类型也不能改变，唯一能改变的是增加varchar类型的长度。添加主键Alter table tab name add primary key(col) 说明：删除主键： Alter tab

4、le tabn ame drop primary key(col)创建索引create uniq ue in dex idx name on tab name(col删除索弓丨：drop in dexidxn ame on tab name注：索引是不可更改的，想更改必须删除重新建。创建视图create view view name as select stateme nt删除视图：drop view view name几个简单的基本的sql语句选择：select * from tablei where 范围插入：insert into table1(field1,field2)values(

5、value1,value2) 删除：delete from tablei where 范围 更新：update tablei set field仁valuel where 范围 查找：select * from tablei where fieldi like ?%valuei%?(所有包含，valuei?这个模式的字符串)-like的语法很精妙， 查资料！排序：select * from tablei order by fieldi,field2 desc 总数：selectcount(*) as totalcount from tablei 求和：select sum(fieldi) as

6、 sumvalue fromtablel 平均：select avg（fieldl） as avgvalue from tablel 最大：select max（fieldl） as maxvalue from table1 最小：select min（field1） as minvalue from table1separator 几个高级查询运算词A: UNION运算符 UNION运算符通过组合其他两个结果表（例如 TABLE1和TABLE2）并消去表中任何重复行而派生出一个结果表。当ALL随UNION 一起使用时（即 UNION ALL ），不消除重复行。两种情况下，派生表 的每一行不是

7、来自 TABLE1就是来自TABLE2。 B: EXCEPT 运算符 EXCEPT运算符通过包括所有在 TABLE1中但不在TABLE2中的行并消除 所有重复行而派生出一个结果表。当ALL随EXCEPT 一起使用时（EXCEPTALL），不消除重复行。C: INTERSECT运算符 INTERSECT运算符通过只包括TABLE1和TABLE2中都有的行并消除所有重复行而派生出一个结 果表。当ALL随INTERSECT 一起使用时（INTERSECT ALL），不消除重复 行。注：使用运算词的几个查询结果行必须是一致的。使用外连接A、left outer join :左外连接（左连接）：结果集既

8、包括连接表的匹配行，也包括左连接表的所有行。SQL: select a.a, a.b, a.c, b.c, b.d, b.f from aLEFT OUT JOIN b ON a.a = b.c B： right outer join:右外连接（右连接）：结果集既包括连接表的匹配连接行，也包括右连接表的所有行。C: full outerjoin :全外连接：不仅包括符号连接表的匹配行，还包括两个连接表中的所有记录。编辑本段提升复制表（只复制结构，源表名:a新表名：b） （Access可用） 法一：select * into b from a where 1<>1 法二：select

9、 top 0 * into b from a拷贝表（拷贝数据,源表名：a目标表名：b） （Access可用）insert into b（a, b, c） select d,e,f from b;跨数据库之间表的拷贝（具体数据使用绝对路径）（Access 可用）insert into b（a, b, c） select d,e,f from b in ,具体数据库？ where条件 例子：.from b inServer.M apPath（".' '&"data.mdb" &"' where.子查询（表名 1: a

10、表名 2: b） select a,b,c from a where a IN （select d from b 或 者:select a,b,c from a where a IN （1,2,3） 显示文章、提交人和最后回复时间select a.title,a.user name,b.adddate from table a,（select max（adddate）adddate from table where table.title=a.title） b外连接查询（表名 1: a 表名 2: b） select a.a, a.b, a.c, b.c, b.d, b.f from a LE

11、FT OUT JOIN b ON a.a = b.c 在线视图查询(表名 1: a select * from (Select a,b,c FROM a) T where t.a > 1; between 的用法between限制查询数据范围时包括了边界值,not between不包括 select * from tablel where time betwee n timel and time2 select a,b,c, from tablel where a not between 数值 1 and 数值 2in的使用方法select * from tablel where a n

12、ot in (, 值 1?,值 2?,值 4?,值 6?)删除主表中已经在副表中没有的信息两张关联表 delete from table1 where not exists ( select * from table2 where table1.field仁table2.field1四表联查问题select * from a left inner joi n b on a.a=b.b right inner join c on a.a=c.c innerjoin d on a.a=d.d where .日程安排提前五分钟提醒SQL: select * from 日程安排 where dated

13、iff('minute',f 开始时间,getdate()>5 一条sql语句搞定数据库分页select top 10 b.* from (select top 20 主键字段，排序字段 from 表名 order by 排序字段desc) a,表名b where b.主键字段=a.主键字段order by a.排序字段 前10条记录select top 10 * form table1 where 范围选择排名选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的 用法可以用于论坛每月排行榜，每月热销产品分析，按科目成绩排名，等等.) select a,b

14、,c from table name ta where a=(select max(a) from table name tb where tb.b=ta.b)派生结果表包括所有在TableA中但不在TableB和TableC中的行并消除所有重复行而派生出一个结果表(select a from tableA except (select a from tableB)except (select a from tableC)随机取出10条数据select top 10 * from table name order by n ewid()随机选择记录select n ewid()删除重复记录De

15、lete from table name where id not in (select max(id) from table name groupby col1,col2,.J列出数据库里所有的表名select n ame from sysobjects where type='U'列出表里的所有的select n ame from syscolu mns where id=object_id('TableName')列示排列一列示type、vender、pcs字段，以type字段排列，case可以方便地实现多重 选择，类似 select 中的 case。se

16、lect type,sum(case vender when 'A' then pcselse 0 en d),sum(case ven der whe n C the n pcs else 0 en d),sum(case ven der whe n 'B' the n pcs else 0 end) FROM table name group by type显示结果：type vender pcs电脑 A 1 电脑 A 1 光盘 B 2 光盘 A 2 手机 B 3手机C 3 初始化表table1TRUNCATE TABLE table1选择从10到15的记录

17、select top 5 * from (select top 15 * from table order by id asc) table_ 另名 order by id desc数据类型转换declare numid int declare id varchar(50)set nu mid=2005setid=convert(varchar,numid)通过上述语句完成数据类型 Int转换成varchar，其他转换类似，可参看 con vert函数编辑本段技巧仁1 , 1=2的使用在SQL语句组合时用的较多“where仁1是表示选择全部“where仁2全部不选，女口：if strWhere

18、 !=' beginset strSQL = 'select cou nt(*)as Total from ' + tblName + ' where ' + strWhere end elsebeg inset strSQL = 'select co un t(*) as Total from ' + tblName + ''end 我们可以直接写成set strSQL = 'select co un t(*) as Total from ' + tblName +'where 1=1 安定

19、9;+ strWhere收缩数据库-重建索引DBCC REINDEX DBCC INDEXDEFRAG-收缩数据和日志 DBCC SHRINKDB DBCC SHRINKFILE压缩数据库dbcc shri nkdatabase(db name)转移数据库给新用户以已存在用户权限exec sp_cha nge_users_log in 'update_ on e',' newn ame','old name'go检查备份集_RESTORE VERIFYONLY from disk='E:dvbbs.bak'修复数据库Alter D

20、ATABASE dvbbs SET SINGLE_USER GO DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCKGO AlterDATABASE dvbbs SET MULTI_USER GO日志清除SET NOCOUNT ON DECLARE LogicalFileName sys name, MaxMi nutes INT, NewSize INTUSE table name - 要操作的数据库名 Select LogicalFileName = 'table name_log',-日志文件

21、名MaxMi nutes = 10, - Limit o n time allowed to wrap log.NewSize = 1 -你想设定的日志文件的大小(M)- Setup / initializeDECLAREOrigi nalSize int Select Origi nalSize = size FROM sysfiles Wheren ame = LogicalFileNameSelect 'Origi nal Size of ' + db_n ame() + ' LOG is'+CONVERT(VARCHAR(30),Orig in alSi

22、ze) + ' 8K pages or ' +CONVERT(VARCHAR(30),(Origi nalSize*8/1024) + 'MB'FROM sysfilesWhere n ame = LogicalFileNameCreate TABLE DummyTra ns(DummyColu mn char (8000) not null)DECLARE Cou nter INT,StartTime DATETIME,Tru ncLog VARCHAR(255)SelectStartTime = GETDATE(), Tru ncLog = 'BAC

23、KUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' DBCC SHRINKFILE (LogicalFileName, NewSize) EXEC (Tru ncLog) - Wrap the log if necessary. WHILE MaxMi nutes > DATEDIFF (mi, StartTime, GETDATE() - time has not expired AND Origi nalSize = (Select size FROM sysfiles Where name = LogicalFileN

24、ame) AND (Orig in alSize * 8 /1024) > NewSize BEGIN -Outer loop. Select Cou nter = 0 WHILE (Cou nter < Origi nalSize / 16) AND (Cou nter < 50000) BEGIN - update In sert DummyTra ns VALUES ('Fill Log') Delete DummyTra nsSelect Cou nter = Cou nter+ 1 END EXEC (Tru ncLog) END Select &#

25、39;Fi nal Size of ' + db_name() + ' LOG is ' + CONVERT(VARCHAR(30),size) + ' 8K pages or ' + CONVERT(VARCHAR(30),(size*8/1024) + 'MB' FROM sysfiles Where n ame = LogicalFileNameDrop TABLE DummyTra nsSETNOCOUNT OFF 更改某个表exec sp_cha ngeobjectow ner 'table name','

26、;dbo'存储更改全部表Create PROCEDURE dbo.User_Cha ngeObjectOw nerBatch as NVARCHAR(128),NewOw ner as NVARCHAR(128)DECLARE Name as NVARCHAR(128) NVARCHAR(128)OldOw ner ASDECLARE Ow ner as DECLARE Ow nerName as NVARCHAR(128)DECLARE curObject CURSOR FOR user_ name(uid)from sysobjectsorder by n ameOPEN curO

27、bjectName, Ow ner Ow ner=OldOw ner rtrim(Name)select 'Name' = n ame,'Ow ner'=where user_ name(uid)=OldOw ner FETCH NEXT FROM curObject INTOWHILE(FETCH_STATUS=0) BEGIN if beginset Ow nerName = OldOw ner + '.' +exec sp_cha ngeobjectow ner Ow nerName, NewOw nerend - select n ame

28、,NewOw ner,OldOw nerFETCH NEXT FROMcurObject INTO Name, Ow nerEND close curObject deallocatecurObject GOSQL SERVER中直接循环写入数据declare i int set i=1 while i<30 beg in in sert into test (userid) values(i) set i=i+1 end:数据库连接代码:SqlConnection objSqlConnection = new SqlConnection ("server = 127.0.0.

29、1;uid = sa; pwd=;database =test"); objSqlConnection.Open(); 二：数据库的添加记录代码：int i = 0; string s1 = "", s2 = ""i = Convert.ToInt16(textBox1.Text);s1 = textBox2.Text;s2 = textBox3.Text;SqlConnection objSqlConnection = new SqlConnection("server = ;uid = sa; pwd =;dat

30、abase =test");objSqlConnection.Open();MessageBox.Show(" 数据库连接成功 ", " 好 ");trySqlCommand sqlcom = new SqlCommand("insert into info(id,name,sex) values( " + i + ",'" + s1 + "','" + s2 + "')", objSqlConnection);sqlcom.Exec

31、uteNonQuery();MessageBox.Show(" 添加成功！ ", " 啊 ");catch (Exception a) MessageBox.Show(a.ToString(); MessageBox.Show(" 添加成功！ ", " 啊 ");三：数据库的修改代码：int i = 0;string s1 = "", s2 = ""s1 = textBox2.Text;s2 = textBox3.Text;if (textBox1.Text.Length =

32、 0)i = 0;elsei = Convert.ToInt32(textBox1.Text);SqlConnection objSqlConnection = new SqlConnection("server = ;uid = sa; pwd =;database =test");objSqlConnection.Open();MessageBox.Show(" 数据库连接成功 ", " 好 ");trysetSqlCommand sqlcom = new SqlCommand("update info

33、 name='"+s1+"',sex='"+s2+"'"+"where id=" + i, objSqlConnection);sqlcom.ExecuteNonQuery();MessageBox.Show(" 修改成功！ ", " 啊 "); objSqlConnection.Close();catch (Exception a) MessageBox.Show(a.ToString(); 四：数据库的删除代码：int i = 0;string s1

34、 = "", s2 = ""s1 = textBox2.Text;s2 = textBox3.Text; if(textBox1.Text.Length=0)i=0;elsei = Convert.ToInt16(textBox1.Text);SqlConnection objSqlConnection = new SqlConnection("server = ;uid = sa; pwd =;database =test");objSqlConnection.Open();MessageBox.Show(&quo

35、t; 数据库连接成功 ", " 好 ");trySqlCommand sqlcom = new SqlCommand("delete from info where id="+i, objSqlConnection);sqlcom.ExecuteNonQuery();MessageBox.Show(" 删除成功！ ", " 啊 "); objSqlConnection.Close();catch (Exception a) MessageBox.Show(a.ToString(); 五：数据库的查询代码：

36、1. 类开始：DataTable dt1 = new DataTable();SqlDataAdapter da1 = new SqlDataAdapter();2. 按钮代码：int i = 0,n=0;string s1 = "", s2 = ""s1 = textBox2.Text;s2 = textBox3.Text;if (textBox1.Text.Length = 0)i = 0;elsei = Convert.ToInt32(textBox1.Text);SqlConnection objSqlConnection = new SqlCo

37、nnection("server = ;uid = sa; pwd =;database =test");objSqlConnection.Open();MessageBox.Show(" 数据库连接成功 ", " 好 ");string query = "SELECT * from info where id="+i;DataSet objDataSet = new DataSet();SqlDataAdapter obj = new SqlDataAdapter();obj.SelectCom

38、mand = new SqlCommand(query, objSqlConnection); obj.Fill(objDataSet, "info");SqlCommand objSqlCommand = new SqlCommand(query, objSqlConnection);SqlDataReader objSqlReader = objSqlCommand.ExecuteReader();while (objSqlReader.Read() n += 1;MessageBox.Show(" 编 号 : " + objSqlReader.Ge

39、tvalue(0) + " 姓 名 :" + objSqlReader.Getvalue(1) + " 性别 " + objSqlReader.Getvalue(2); if (n = 0)MessageBox.Show(" 数据库中没有这样的记录！ "); 六：数据库的查询代码：int i = 0;/ int n = 0;string s1 = "", s2 = ""string sql;s1 = textBox2.Text;s2 = textBox3.Text;if (textBox1.Text.Length = 0)i = 0;elsei = Convert.ToInt32(textBox1.Text);SqlConnection objSqlConnection = new SqlConnection("server = ;uid = sa; pwd =;database =tes