SQL显示库存更新

Question

我有一个表格，显示库存的所有更新：

╔══════════════╦════════╦══════════╦═══════╗
║   ItemName   ║  Type  ║ Quantity ║ Date  ║
╠══════════════╬════════╬══════════╬═══════╣
║ BottledWater ║ Add    ║       50 ║ 07/03 ║
║ BottledWater ║ Deduct ║       20 ║ 07/03 ║
║ Chips        ║ Add    ║       30 ║ 07/02 ║
║ BottledWater ║ Deduct ║       10 ║ 07/02 ║
║ Chips        ║ Deduct ║       20 ║ 07/01 ║
╚══════════════╩════════╩══════════╩═══════╝

我想写一个查询并返回一个表格，该表格会显示已添加和扣除的股票的总数，该表格如下所示：

╔══════════════╦═══════╦══════════╗
║   ItemName   ║ Added ║ Deducted ║
╠══════════════╬═══════╬══════════╣
║ BottledWater ║    50 ║       30 ║
║ Chips        ║    30 ║       20 ║
╚══════════════╩═══════╩══════════╝

有什么想法吗？

Answer 1

只需使用条件聚合：

0000000 b848 beef dead babe cafe               
000000a

Answer 2

语法稍微关闭，但这是伪代码：

select ItemName, sum(Type==add) as added, sum(Type==deduct) as deducted, from inventory group by ItemName