SQL Server 2008(版本10.50.2550) .
我有一个选择查询来返回uniqueidentifier类型的单个列 .
我想把它变成Guid类型的C#变量 .
以下所有方法都会导致异常 .
reader的类型为SqlDataReader .
using (var reader = command.ExecuteReader())
{
if (reader.Read())
{
Guid guid = reader.GetGuid(reader.GetOrdinal("integ_schemehistoryId")); //1
Guid guid = Guid.Parse((string)reader["integ_schemehistoryId"]); //2
Guid guid = (Guid)reader["integ_schemehistoryId"]; //3
Guid guid = new Guid((string)reader["integ_schemehistoryId"]); //4
Guid guid = Guid.Parse(reader["integ_schemehistoryId"].ToString()); //5
}
}
错误1:
System.Data.SqlClient.SqlException (0x80131904): Conversion failed when converting from a character string to uniqueidentifier.
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()
at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
at System.Data.SqlClient.SqlDataReader.HasMoreRows()
at System.Data.SqlClient.SqlDataReader.ReadInternal(Boolean setTimeout)
at System.Data.SqlClient.SqlDataReader.Read()
at Simego.DataSync.DynamicColumns.DataSourceRowOverride.get_EpochSchemeHistoryID()
错误2:
System.InvalidCastException: Unable to cast object of type 'System.Guid' to type 'System.String'.
at Simego.DataSync.DynamicColumns.DataSourceRowOverride.get_EpochSchemeHistoryID()
错误3:
System.Data.SqlClient.SqlException (0x80131904): Conversion failed when converting from a character string to uniqueidentifier.
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()
at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
at System.Data.SqlClient.SqlDataReader.HasMoreRows()
at System.Data.SqlClient.SqlDataReader.ReadInternal(Boolean setTimeout)
at System.Data.SqlClient.SqlDataReader.Read()
at Simego.DataSync.DynamicColumns.DataSourceRowOverride.get_EpochSchemeHistoryID()
错误4:
System.InvalidCastException: Unable to cast object of type 'System.Guid' to type 'System.String'.
at Simego.DataSync.DynamicColumns.DataSourceRowOverride.get_EpochSchemeHistoryID()
5的错误:
System.Data.SqlClient.SqlException (0x80131904): Conversion failed when converting from a character string to uniqueidentifier.
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()
at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
at System.Data.SqlClient.SqlDataReader.HasMoreRows()
at System.Data.SqlClient.SqlDataReader.ReadInternal(Boolean setTimeout)
at System.Data.SqlClient.SqlDataReader.Read()
at Simego.DataSync.DynamicColumns.DataSourceRowOverride.get_EpochSchemeHistoryID()
6 回答
您的数据或SQL存在问题 . 第一种和第三种方法应该有效 - 我个人会使用第一种形式,因为它在我看来是最清晰的 .
但是看看堆栈跟踪:
...位于Simego.DataSync.DynamicColumns.DataSourceRowOverride.get_EpochSchemeHistoryID()的System.Data.SqlClient.SqlDataReader.Read()处的System.Data.SqlClient.SqlDataReader.ReadInternal(Boolean setTimeout)
请注意,这是
Read()
调用失败,而不是GetGuid
或索引器 .我的猜测是你的属性被多次获取,有时它可以工作 - 这就是你在第二种方法中获得强制转换异常的原因 - 但是对于某些行,它由于数据或SQL的某些问题而失败 . 因为我们帮助你超越诊断,但那是你应该在下一步看的地方 .
你有没有尝试过:
尝试使用
Guid.Parse
method该错误是从SQL生成的 . 换句话说,SQL命令文本有问题 . 不是你的c#代码 .
正如其他答案所示,你应该尝试:
您可能还想检查存储过程和表格,可能存在问题 .