php - 在我的 sql codeigniter 中互相添加减去数据库字段

Question

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Answer 1

不确定您是否可以使用 CI 事件记录来执行此操作，但您可以编写 SQL 查询并使用 $this->db->query($query) 运行它

您的查询可以是这样的:

SELECT
    *
FROM
    (
        SELECT
            SUM(quantity) AS addqty_add,
            SUM(total_cost) AS addcost_add
        FROM
            tbName
        WHERE
            warehouse_id = 2
        AND inventory_type = 'add'
    ) AS tb1,
    (
        SELECT
            SUM(quantity) AS addqty_remove,
            SUM(total_cost) AS addcost_remove
        FROM
            tbName
        WHERE
            warehouse_id = 2
        AND inventory_type = 'remove'
    ) AS tb2