Question

在我的查询中使用动态SQL时SET赋值（SET @running_total_available：= 0;）在哪里？

我的查询工作正常如图所示，但＆＃34; @running总计......＆＃34;当我使用SET @running_total_available：= 0

时崩溃查询

并将每一行重置为＆＃34; 0＆＃34;不使用SET。

我很难过。谢谢！

    $sql = "
        SELECT
            SQL_CALC_FOUND_ROWS
            @running_total_available := 0,
            product_source, 
            username, 
            product_short_name,
            noci_count,
            item_listing_id, 
            IF(num_purchased=0,'', num_purchased) AS num_purchased ,
            IF(num_available=0,'', num_available) AS num_available,
            IF(num_sold=0,'', num_sold) AS num_sold,
            i.tot_items, 
            date(date_listing_noci) AS date_listing_noci, 
            IFNULL(date(date_listing_removed),'') AS date_listing_removed,
            @running_total_purchased:=@running_total_purchased + i.num_purchased  AS running_total_purchased,
            @running_total_available:=@running_total_available + i.num_available AS running_total_available,
            @running_total_sold:=@running_total_sold + i.num_sold  AS running_total_sold,
            @running_total_item:=@running_total_item + i.num_sold + i.num_available AS running_total_item,
            @running_total_noci:=@running_total_noci + i.noci_count AS running_total_noci
        FROM 
            (SELECT 
                product_source, 
                item_listing_id,
                p.product_short_name, 
                username, 
                noci_count,
                IF(num_purchased=0,0,num_purchased) AS num_purchased,
                IFNULL(num_available,0) AS num_available, 
                IFNULL(num_sold,0) AS num_sold,
                IFNULL(num_sold,0) + IFNULL(num_available,0) AS tot_items,
                date(date_listing_noci) AS date_listing_noci,
                IFNULL(date(date_listing_removed),'') AS date_listing_removed
            FROM `investigation`   
            JOIN product p USING (product_id)   
            WHERE 1 ";

                *** dynamic constructs here ***

    # close query
    $sql.=  " ) i ";


    $result = $objDbMysqli->query($sql);

Answer 1

在交叉连接的子查询中初始化它：

    SELECT
        ...
    FROM (
        ...
        JOIN product p USING (product_id)   
        WHERE 1 
    ) i
    CROSS JOIN (select @running_total_available := 0) initvars

使用它会自行承担风险，因为无法保证执行顺序。

如何在动态SQL查询中设置用户定义的变量？

1 个答案: