关于C#,System.InvalidOperationException的问题,请高手帮忙!
这是我的源代码,请各位大虾帮帮忙,谢谢!classClassDB{privateSqlConnectionmysqlconn;//连接数据库publicvoidDB_Li...
这是我的源代码,请各位大虾帮帮忙,谢谢!
class ClassDB
{
private SqlConnection mysqlconn;
//连接数据库
public void DB_Link()
{
try
{
mysqlconn = new SqlConnection("Server=local; Database=wms;uid=sa;pwd=;");
mysqlconn.Open();
}
catch (Exception e)
{
}
}
//获取数据
public DataSet DB_List(String sql)
{
this.DB_Link();
SqlDataAdapter sda = new SqlDataAdapter(sql,mysqlconn);
DataSet ds = new DataSet();
sda.Fill(ds,"guest");
return ds;
}
//插入数据
public void DB_Insert(String sql)
{
}
//删除数据
public void DB_Delete(String sql)
{
}
//修改数据
public void DB_Update(String sql)
{
}
//查询数据
public Boolean DB_Select(String sql)
{
this.DB_Link();
SqlDataAdapter sda = new SqlDataAdapter(sql, mysqlconn);
sda.SelectCommand = new SqlCommand(sql, mysqlconn);
int n = sda.SelectCommand.ExecuteNonQuery();
if (n == 0)
{
return false;
}
else
{
return true;
}
}
// 关闭数据库
public void DB_Close()
{
mysqlconn.Close();
}
}
数据库的服务已打开 展开
class ClassDB
{
private SqlConnection mysqlconn;
//连接数据库
public void DB_Link()
{
try
{
mysqlconn = new SqlConnection("Server=local; Database=wms;uid=sa;pwd=;");
mysqlconn.Open();
}
catch (Exception e)
{
}
}
//获取数据
public DataSet DB_List(String sql)
{
this.DB_Link();
SqlDataAdapter sda = new SqlDataAdapter(sql,mysqlconn);
DataSet ds = new DataSet();
sda.Fill(ds,"guest");
return ds;
}
//插入数据
public void DB_Insert(String sql)
{
}
//删除数据
public void DB_Delete(String sql)
{
}
//修改数据
public void DB_Update(String sql)
{
}
//查询数据
public Boolean DB_Select(String sql)
{
this.DB_Link();
SqlDataAdapter sda = new SqlDataAdapter(sql, mysqlconn);
sda.SelectCommand = new SqlCommand(sql, mysqlconn);
int n = sda.SelectCommand.ExecuteNonQuery();
if (n == 0)
{
return false;
}
else
{
return true;
}
}
// 关闭数据库
public void DB_Close()
{
mysqlconn.Close();
}
}
数据库的服务已打开 展开
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