[英]Calculate running balance in mysql select query and view
我的簡單表使用以下各列命名為material:
mat_id mat_name stock_in stock_released date
1 alloy 30 0 feb13
2 steel 15 0 feb13
3 alloy 0 3 feb14
如何生成或將其計算為:
mat_id mat_name stock_in stock_released Balance date
1 alloy 30 0 30 feb13
2 steel 15 0 15 feb13
3 alloy 0 3 15 feb14
這是我現有的代碼,但是天平有問題,因為它不考慮物料名稱,總計所有內容:
SELECT
`material`.`mat_id`,
`material`.`mat_name`,
`material`.`stock_in`,
`material`.`stock_released`,
@Balance := @Balance + `material`.`stock_in` - `material`.`stock_released` AS `Balance`,
`material`.`date`
FROM `material`, (SELECT @Balance := 0) AS variableInit
WHERE mat_name = mat_name
ORDER BY `material`.`mat_id` ASC
如何以此創建視圖?
使用此數據,獲得運行余額的查詢為:
SELECT m.`mat_id`, m.`mat_name`, m.`stock_in`, m.`stock_released`,
(select sum(stock_in) - sum(stock_released)
from material m2
where m2.mat_name = m.mat_name and
m2.mat_id <= m.mat_id
) as balance,
m.`date`
FROM `material` m
ORDER BY m.`mat_id` ASC;
您可以將其放入視圖。
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