的系统中有的就是变量参数用的这种类似特殊符号，肯定也是为了兼容多数据库所作的处理了，呵呵，具体的调用及测试之后统一说明。还有几个方法也和上面类似，大家都熟悉的。如下（不再做具体解释了）：
/// <summary>
/// 执行SQL语句并返回DataReader对象
/// </summary>
/// <param name="dbcon"></param>
/// <param name="cmdText"></param>
/// <returns></returns>
public DbDataReader ExecuteDataReader(DbConnection dbcon,string cmdText)
{
try
{
if (dbcon.State == ConnectionState.Closed)
{
dbcon.Open();
}
cmd.CommandText = Replace(cmdText);
DbDataReader dr = cmd.ExecuteReader();
cmd.Parameters.Clear();
cmd.Dispose();
return dr;
}
catch
{
dbcon.Close();//发生异常在此处关闭，否则在调用显式处关闭
return null;
}
}
/// <summary>
/// 判断记录是否存在
/// </summary>
/// <param name="Sql"></param>
/// <returns></returns>
public bool Exist(string Sql)
{
bool exist;
this.Open();
cmd.CommandText = Replace(Sql);
DbDataReader dr = cmd.ExecuteReader();
if (dr.HasRows)
{
exist = true; //记录存在
}
else
{
exist = false; //记录不存在
}
dr.Close();
this.Close();
return exist;
}
/// <summary>
/// 执行SQL语句
/// </summary>
/// <param name="sql"></param>
public void ExecSql(string Sql)
{
try
{
this.Open();
cmd.CommandText = Replace(Sql);
cmd.ExecuteNonQuery();
cmd.Dispose();
}
catch (Exception ex)
{
throw ex;
}
finally
{
this.Close();
}
}
/// <summary>
/// 执行SQL语句,返回一个单值
/// </summary>
/// <param name="sql"></param>
/// <returns></returns>
public string ReturnValue(string Sql)
{
object returnValue = string.Empty;
try
{
this.Open();
cmd.CommandText = Replace(Sql);
returnValue = cmd.ExecuteScalar();
if (returnValue == null)
{
returnValue = string.Empty;
}
}
catch (Exception ex)
{
throw ex;
}
finally
{
this.Close();
}
return returnValue.ToString();
}
/// <summary>
/// 执行多条SQL语句并启用数据库事务
/// </summary>
/// <param name="SQLStringList"></param>
public bool ExecSqlTran(List<String> SQLStringList)
{
this.Open();
DbTransaction trans = conn.BeginTransaction();
cmd.Transaction = trans;
try
{
for (int n = 0; n < SQLStringList.Count; n++)
{
cmd.CommandText = Replace(SQLStringList[n]);
cmd.ExecuteNonQuery();
}
trans.Commit();
return true;
}
catch
{
trans.Rollback();
return false;
}
finally
{
this.Close();
