C#MySQL示例Command.ExecuteReader引发异常
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我正在编写一段C#代码,以从mysql数据库中获取一些数据.我已经从现成的示例开始,但是它在rdr = cmd.ExecuteReader()时给了我一个错误.
抛出异常的屏幕快照也如下所示
using System;
using MySql.Data.MySqlClient;
public class Program
{
static void Main()
{
string serverName = "192.168.0.012";
string port = "1234";
string db = "cust_db";
string userID = "root";
string password = "pass";
string cs = "Server=" + serverName + ";Port=" + port + ";Database=" + db + ";Uid=" + userID + ";password=" + password;
MySqlConnection conn = null;
MySqlDataReader rdr = null;
try
{
conn = new MySqlConnection(cs);
conn.Open();
string stm = "SELECT * FROM cust_tb";
MySqlCommand cmd = new MySqlCommand(stm, conn);
rdr = cmd.ExecuteReader();
while (rdr.Read())
{
Console.WriteLine(rdr.GetInt32(0) + ": "
+ rdr.GetString(1));
}
} catch (MySqlException ex)
{
Console.WriteLine("Error: {0}", ex.ToString());
} finally
{
if (rdr != null)
{
rdr.Close();
}
if (conn != null)
{
conn.Close();
}
}
}
}
at MySql.Data.MySqlClient.CharSetMap.GetChararcterSet(DBVersion version, String CharSetName)
at MySql.Data.MySqlClient.NativeDriver.GetFieldMetaData41()
at MySql.Data.MySqlClient.NativeDriver.GetFieldMetaData()
at MySql.Data.MySqlClient.NativeDriver.ReadColumnMetadata(Int32 count)
at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader()
at Program.Main() in c:\Users\omran.alhammadi\Desktop\csMysqlConnection\csMysqlConnection\Program.cs:line 28
at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()</StackTrace><ExceptionString>System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
at MySql.Data.MySqlClient.CharSetMap.GetChararcterSet(DBVersion version, String CharSetName)
at MySql.Data.MySqlClient.NativeDriver.GetFieldMetaData41()
at MySql.Data.MySqlClient.NativeDriver.GetFieldMetaData()
at MySql.Data.MySqlClient.NativeDriver.ReadColumnMetadata(Int32 count)
at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader()
at Program.Main() in c:\Users\omran.alhammadi\Desktop\csMysqlConnection\csMysqlConnection\Program.cs:line 28
at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()</ExceptionString></Exception></TraceRecord>
An unhandled exception of type 'System.Collections.Generic.KeyNotFoundException' occurred in mscorlib.dll
Additional information: The given key was not present in the dictionary.
The program '[17084] csMysqlConnection.vshost.exe: Managed (v4.0.30319)' has exited with code -1 (0xffffffff).
解决方法:
我一直遇到这个问题,并且做了一些研究.过了一会儿,我才解决了这个问题.
我的问题是数据库表编码.我有utf32_unicode_ci,然后将其更改为utf8_unicode_ci.现在,它可以完美运行.
希望你有运气.
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