以下是出错信息~~~==================================无法连接到 (local)。===================================在与 SQL Server 建立连接时出现与网络相关的或特定于实例的错误。未找到或无法访问服务器。请验证实例名称是否正确并且 SQL Server 已配置为允许远程连接。 (provider: 命名管道提供程序, error: 40 - 无法打开到 SQL Server 的连接) (.Net SqlClient Data Provider)------------------------------
有关帮助信息,请单击: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&EvtSrc=MSSQLServer&EvtID=2&LinkId=20476------------------------------
错误号: 2
严重性: 20
状态: 0
------------------------------
程序位置: 在 System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
在 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
在 System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, SqlConnection owningObject)
在 System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject)
在 System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart)
在 System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance)
在 System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance)
在 System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection)
在 System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup)
在 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
在 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
在 System.Data.SqlClient.SqlConnection.Open()
在 Microsoft.SqlServer.Management.UI.VSIntegration.ObjectExplorer.ObjectExplorer.ValidateConnection(UIConnectionInfo ci, IServerType server)
在 Microsoft.SqlServer.Management.UI.ConnectionDlg.Connector.ConnectionThreadUser()SQL
有关帮助信息,请单击: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&EvtSrc=MSSQLServer&EvtID=2&LinkId=20476------------------------------
错误号: 2
严重性: 20
状态: 0
------------------------------
程序位置: 在 System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
在 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
在 System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, SqlConnection owningObject)
在 System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject)
在 System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart)
在 System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance)
在 System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance)
在 System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection)
在 System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup)
在 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
在 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
在 System.Data.SqlClient.SqlConnection.Open()
在 Microsoft.SqlServer.Management.UI.VSIntegration.ObjectExplorer.ObjectExplorer.ValidateConnection(UIConnectionInfo ci, IServerType server)
在 Microsoft.SqlServer.Management.UI.ConnectionDlg.Connector.ConnectionThreadUser()SQL
1、确定数据库的协议配置打开了没有?TCP/IP开了?VIA协议关闭了没?
2、确定本机上的服务开了没?记下实例名称。
3、在VS2012下用集成的SQL测试功能测试,注意要写好机器名\实例名。
1、SQLServer引擎开启没有?
2、SQLServer是否有多实例?local只是默认实例,如果你还有express,很有可能就连错了
3、named piped 、sql browser开一下吧。
4、如果你不知道要怎么连,打开SSMS,在服务器那里下拉再浏览。看看有什么可用的实例名
上次安装的是SQLManagementStudio_x86_CHS。
group by 成绩表.Student_ID
Having avg(Score) > (select avg(成绩表.Score)as 全部平均分 from 成绩表) )报出【当没有用 EXISTS 引入子查询时,在选择列表中只能指定一个表达式。】
select * from 成绩表
select * from 课程表
insert into 学生表 (Student_ID,Name,Age)values('01','Sam',15)
insert into 学生表 (Student_ID,Name,Age)values('02','Tom',14)
insert into 学生表 (Student_ID,Name,Age)values('03','Jim',13)
insert into 成绩表 (Grade_ID,Student_ID,Subject_ID,Score)values('101','01','A',95)
insert into 成绩表 (Grade_ID,Student_ID,Subject_ID,Score)values('101','01','B',96)
insert into 成绩表 (Grade_ID,Student_ID,Subject_ID,Score)values('101','01','C',99)
insert into 成绩表 (Grade_ID,Student_ID,Subject_ID,Score)values('101','02','A',85)
insert into 成绩表 (Grade_ID,Student_ID,Subject_ID,Score)values('101','02','B',86)
insert into 成绩表 (Grade_ID,Student_ID,Subject_ID,Score)values('101','02','C',89)
insert into 成绩表 (Grade_ID,Student_ID,Subject_ID,Score)values('101','03','A',100)
insert into 成绩表 (Grade_ID,Student_ID,Subject_ID,Score)values('101','03','B',98)
insert into 成绩表 (Grade_ID,Student_ID,Subject_ID,Score)values('101','03','C',99)
insert into 课程表 (Subject_ID,Subject_Name)values('A','CH')
insert into 课程表 (Subject_ID,Subject_Name)values('B','EN')
insert into 课程表 (Subject_ID,Subject_Name)values('C','MA')select 学生表.Student_ID,学生表.Name from 学生表,成绩表 where 学生表.Student_ID =
(select 成绩表.Student_ID ,avg(Score)as 个人平均分 from 成绩表
group by 成绩表.Student_ID
Having avg(Score) > (select avg(成绩表.Score)as 全部平均分 from 成绩表) )实现个人平均分 大于 总体平均分 的学生?
(select 成绩表.Student_ID from 成绩表
group by 成绩表.Student_ID
Having avg(Score) > (select avg(成绩表.Score)as 全部平均分 from 成绩表) )