帮帮忙:ExecuteNonQuery 要求已打开且可用的连接。连接的当前状态为已关闭
using System;using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Windows.Forms;
using System.Data.OleDb;
namespace StudentMangerSystem
{
class DBConn
{
//==============建立连接=================================
public static OleDbConnection DBCon()
{
String connectionString =
"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|xb.mdb";
return new OleDbConnection(connectionString);
}
public static DialogResult MessageOk(string value)
{
return MessageBox.Show(value, "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
public static DataTable ExecSqlReturnDataTable(string SqlStr)
{
DataSet ds = new DataSet();
DataTable table = new DataTable();
OleDbConnection con = DBCon();
try
{
OleDbDataAdapter da = new OleDbDataAdapter(SqlStr, con);
da.Fill(ds, "Table");
table = ds.Tables["Table"];
return table;
}
catch (Exception ex)
{
con.Close();
DBConn.MessageOk(ex.Message);
return table;
}
finally
{
con.Close();
}
}
/// <summary>
public static bool ExecSqlReturn(string SqlStr, string ParaPic, byte[] Pic)
{
OleDbConnection con = DBCon();
OleDbCommand com = new OleDbCommand();
com.Parameters.Add(ParaPic, OleDbType.Date);
com.Parameters[0].Value = Pic;
com.Connection = con;
com.CommandText = SqlStr;
try
{
com.ExecuteNonQuery();
con.Close();
return true;
}
catch (Exception ex)
{
DBConn.MessageOk(ex.Message);
return false;
}
finally
{
con.Close();
}
}
/// <summary>
public static bool ExecSqlReturn(string SqlStr)
{
OleDbConnection con = DBCon();
OleDbCommand com = new OleDbCommand();
com.Connection = con;
com.CommandText = SqlStr;
try
{
com.ExecuteNonQuery();
con.Close();
return true;
}
catch (Exception ex)
{
DBConn.MessageOk(ex.Message);
return false;
}
finally
{
con.Close();
}
}
/// <summary>
/// 返回单一值的查询
/// </summary>
public static object ExecSqlScalar(string SqlStr)
{
OleDbConnection con = DBCon();
OleDbCommand com = new OleDbCommand();
com.Connection = con;
com.CommandText = SqlStr;
try
{
return com.ExecuteScalar();
}
catch
{
con.Close();
return null;
}
finally
{
con.Close();
}
}
}
}
紧急啊~~ --------------------编程问答-------------------- 你的con都没有open过,必须报错啊
//==============建立连接=================================
public static OleDbConnection DBCon()
{
String connectionString =
"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|xb.mdb";
OleDbConnection con = new OleDbConnection(connectionString);
con.Open();
return con;
} --------------------编程问答--------------------
using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Windows.Forms;
using System.Data.OleDb;
namespace StudentMangerSystem
{
class DBConn
{
//==============建立连接=================================
public static OleDbConnection DBCon()
{
String connectionString =
"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|xb.mdb";
OleDbConnection con = new OleDbConnection(connectionString);
if (con .State != ConnectionState.Open)
{
con.Open(); //打开连接
}
return con;
}
public static DialogResult MessageOk(string value)
{
return MessageBox.Show(value, "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
public static DataTable ExecSqlReturnDataTable(string SqlStr)
{
DataSet ds = new DataSet();
DataTable table = new DataTable();
OleDbConnection con = DBCon();
try
{
OleDbDataAdapter da = new OleDbDataAdapter(SqlStr, con);
da.Fill(ds, "Table");
table = ds.Tables["Table"];
return table;
}
catch (Exception ex)
{
con.Close();
DBConn.MessageOk(ex.Message);
return table;
}
finally
{
con.Close();
}
}
/// <summary>
public static bool ExecSqlReturn(string SqlStr, string ParaPic, byte[] Pic)
{
OleDbConnection con = DBCon();
OleDbCommand com = new OleDbCommand();
com.Parameters.Add(ParaPic, OleDbType.Date);
com.Parameters[0].Value = Pic;
com.Connection = con;
com.CommandText = SqlStr;
try
{
com.ExecuteNonQuery();
con.Close();
return true;
}
catch (Exception ex)
{
DBConn.MessageOk(ex.Message);
return false;
}
finally
{
con.Close();
}
}
/// <summary>
public static bool ExecSqlReturn(string SqlStr)
{
OleDbConnection con = DBCon();
OleDbCommand com = new OleDbCommand();
com.Connection = con;
com.CommandText = SqlStr;
try
{
com.ExecuteNonQuery();
con.Close();
return true;
}
catch (Exception ex)
{
DBConn.MessageOk(ex.Message);
return false;
}
finally
{
con.Close();
}
}
/// <summary>
/// 返回单一值的查询
/// </summary>
public static object ExecSqlScalar(string SqlStr)
{
OleDbConnection con = DBCon();
OleDbCommand com = new OleDbCommand();
com.Connection = con;
com.CommandText = SqlStr;
try
{
return com.ExecuteScalar();
}
catch
{
con.Close();
return null;
}
finally
{
con.Close();
}
}
}
}
补充:.NET技术 , C#