最近一次盘点数量，入库数量，出库数量是在3个不同的表中，请重写

既然最近一次盘点数量、入库数量以及出库数量分别分布在三个不同的表中，我们需要合并这些数据。假设这三个表分别是`InventoryCheckpoints`(盘点记录)，`StockInventories`(入库记录) 和 `StockOuts`(出库记录)。我们可以使用JOIN语句来关联它们：

SELECT I.MatName AS '物料名称',
       (LC.Quantity + SI.Quantity - O.Quantity) AS '实时库存'
FROM InventoryCheckpoints LC
JOIN (SELECT MatName, SUM(Quantity) AS Quantity
      FROM StockInventories
      WHERE InventoryDate = (SELECT MAX(InventoryDate) FROM StockInventories)
      GROUP BY MatName) SI ON LC.MatName = SI.MatName
JOIN (SELECT MatName, SUM(Quantity) AS Quantity
      FROM StockOuts
      WHERE InventoryDate = (SELECT MIN(InventoryDate) FROM StockOuts)
      GROUP BY MatName) O ON LC.MatName = O.MatName
WHERE LC.InventoryDate = (SELECT MAX(InventoryDate) FROM InventoryCheckpoints);

这个查询首先找到每个物料的最新盘点信息(`LC`)，然后结合最新入库记录(`SI`)和最早出库记录(`O`)计算库存量。