如何将执行读取器用于不同的变量

>我使用ExecuteScalar进行单个查询，如下所示：

try
{
    OleDbConnection Connection;
    using (Connection = new OleDbConnection("Provider=MSDAORA.1;Data Source=DATABASE:1521/orcl;Persist Security Info=True;Password=PASSWORD;User ID=USERNAME"))
    {
    OleDbCommand Command1, Command2, Command3;
    Command1 = new OleDbCommand("SELECT HOUR FROM Table1 WHERE type='CAR' and name='FERRARI'",", Connection);
    Command2 = new OleDbCommand("SELECT HOUR FROM Table1 WHERE type='CAR' and name='FORD'", Connection);
    Command3 = new OleDbCommand("SELECT HOUR FROM Table1 WHERE type='CAR' and name='OPEL'", Connection);
    Connection.Open();
    var1 = (int)Command1.ExecuteScalar();
    var2 = (int)Command2.ExecuteScalar();
    var3 = (int)Command3.ExecuteScalar();
    Connection.Close();
} 

它对我来说工作正常。但是 3 个（以及其他数据库的更多）查询由于数据库而等待了很长时间。如何选择所有表（从表1中选择*）并在为每个where条件执行命令后？你能在我的示例代码上给我看这个例子吗？谢谢。