Server Error in '/' Application.

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Line 51:         conn.ConnectionString = ConfigurationSettings.AppSettings["SQLConnectionString"];//给连接字符串赋值
Line 52:     
Line 53:         conn.Open();//打开数据库
Line 54:         try
Line 55:         {

[SqlException (0x80131904): 无法打开登录所请求的数据库 "jg0"。登录失败。
用户 'sa' 登录失败。]
   System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection) +357
   System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection) +79
   System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection) +201
   System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +156
   System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +22
   System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry) +92
   System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry) +219
   System.Data.SqlClient.SqlConnection.Open() +101
   s41.GreatDs(String sql) in d:\web\JG\dygs.jgdyde.com\s41.aspx.cs:53
   s41.Page_Load(Object sender, EventArgs e) in d:\web\JG\dygs.jgdyde.com\s41.aspx.cs:17
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +52
   System.Web.UI.Control.OnLoad(EventArgs e) +97
   System.Web.UI.Control.LoadRecursive() +61
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +693