Mysql 单行中的多行

我陷入了一个混乱的结构中，在编写查询时需要帮助，这是我当前的查询

SQL:

SELECT  `name` , trnid,  `material` , SUM( quantity )qty , SUM( price ) price, SUM( preturn ) return 
FROM  `transactions` a
JOIN item_master b ON a.material = b.id
GROUP BY material, trnid
LIMIT 0 , 30

输出：

SELECT  `name` , trnid,  `material` , SUM( quantity )qty , SUM( price ) price, SUM( preturn ) return 
FROM  `transactions` a
JOIN item_master b ON a.material = b.id
GROUP BY material, trnid
LIMIT 0 , 30

如果您看到上面有两条相同物料的记录（trnd 1为采购数量，trnd 2为出库数量），我希望这些记录是一条具有以下列的记录

name | material | purqty | issqty  

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我认为您需要条件聚合：

SELECT  name, material,
        SUM(case when trnid = 1 then quantity else 0 end) as purchaseqty,
        SUM(case when trnid = 2 then quantity else 0 end) as issueqty
FROM transactions t JOIN
     item_master im
     ON t.material = im.id
GROUP BY name, material
LIMIT 0 , 30;

---

我认为您需要条件聚合：

SELECT  name, material,
        SUM(case when trnid = 1 then quantity else 0 end) as purchaseqty,
        SUM(case when trnid = 2 then quantity else 0 end) as issueqty
FROM transactions t JOIN
     item_master im
     ON t.material = im.id
GROUP BY name, material
LIMIT 0 , 30;

---

完美和被接受的唯一一件事是，我只需要按材料分组并删除名称，以根据我的结构得到正确的结果。谢谢：）完美且被接受的唯一一件事是我只需要按材料分组并删除名称，以根据我的结构得到正确的结果。谢谢：）