C# C TableAdapter可选WHERE子句

我在QueryBuilder中有这样一个查询：

SELECT Items    FROM     Tables
WHERE  (Transactions.transaction_type = ? AND
Items.designation LIKE '%'+?+'%' AND Transactions.transaction_date >= ?
AND Transactions.transaction_date <= ? AND Items.item_number = ?)

但是，我并不总是希望按项目编号进行筛选，因此：是否可以临时忽略WHERE子句，或者像在指定参数中那样设置空值，而不在设计器中创建单独的查询？

现在开始：

SELECT Items FROM Tables
WHERE Transactions.transaction_type = @TransatctionType AND
Items.designation LIKE '%'+ @Designation +'%'
AND Transactions.transaction_date >= @DateFrom
AND Transactions.transaction_date <= @DateTo 
AND (@ItemNumber IS NULL OR Items.item_number = @ItemNumber)

不创建新查询的原因是什么？在这种情况下，代码更易于维护

SELECT Items FROM Tables
WHERE Transactions.transaction_type = @TransatctionType AND
Items.designation LIKE '%'+ @Designation +'%'
AND Transactions.transaction_date >= @DateFrom
AND Transactions.transaction_date <= @DateTo 
AND (@ItemNumber IS NULL OR Items.item_number = @ItemNumber)