private string GetNullValueOperator(NullValueOperator op)
{
string opStr = "";
switch (op)
{
case NullValueOperator.Is:
opStr = " is ";
break;
case NullValueOperator.IsNot:
opStr = " is not ";
break;
}
return(opStr);
}
/// <summary>
/// 指定某列值为NULL的查询。该方法可连续调用。由于使用Where方法指定某列值为null(如：columnName is @arg，@arg为null)时会出错，所以有了该方法。
/// </summary>
/// <param name="logicOperator">逻辑操作符</param>
/// <param name="columnName">列名</param>
/// <param name="valueOperator">值操作符</param>
/// <returns></returns>
public Command NullWhere(LogicOperator logicOperator, string columnName, NullValueOperator valueOperator)
{
whereString += GetLogicOperator(logicOperator) + columnName + GetNullValueOperator(valueOperator) + " null ";
return(this);
}
/// <summary>
/// 指定某列值为NULL。该方法可连续调用。
/// </summary>
/// <param name="logicOperator">逻辑操作符</param>
/// <param name="columnName">列名</param>
/// <param name="valueOperator">值操作符</param>
/// <returns></returns>
public new SelectCommand NullWhere(LogicOperator logicOperator, string columnName, NullValueOperator valueOperator)
{
base.NullWhere(logicOperator, columnName, valueOperator);
return(this);
}
