/// <returns>string</returns>
protected abstract string GetCompareType();
}
/// <summary>
/// 等于表达式
/// </summary>
[Serializable]
public class EqExpression:BaseExpression
{
/// <summary>
/// 构造等于表达式对象
/// </summary>
public EqExpression()
{
}
/// <summary>
/// 构造指定名称和值的等于表达式对象
