Question

我正在搜索某些表，我想计算表的结果，当它在我设置的日期没有数据时，我想显示数字零。

SELECT 
    l.key as "Licença",
    coalesce(sum(c."customersAmount"), 0) as "Comsumo dos ultimos 30 dias"
FROM
    consumptions c
LEFT JOIN licenses l on c."licenseKey"=l.key
WHERE 
    c."consumedAt" >= current_date - interval '30' day AND
    l.label LIKE '%Casa%'
GROUP BY 
    l.key
ORDER BY 
    l.key ASC;

没有消耗的lkey，我想显示数字零（0）。

我该怎么做？谢谢

Answer 1

您可以使用

CASE WHEN l.key NULL THEN 'Empty' ELSE l.key END as "Licença"

或

coalesce(l.key, 'Empty') AS "Licença"

Answer 2

您应将c."consumedAt" >= current_date - interval '30' day从WHERE移到ON子句。在WHERE中，它过滤掉所有的行，其中licenses中没有行被连接，因为"consumedAt"的行从不为空，并且永远不会大于或等于任何其他值。

SELECT l.key "Licença",
       coalesce(sum(c."customersAmount"), 0) "Comsumo dos ultimos 30 dias"
       FROM consumptions c
            LEFT JOIN licenses l
                      ON c."licenseKey" = l.key
                         AND c."consumedAt" >= current_date - interval '30' day
       WHERE l.label LIKE '%Casa%'
       GROUP BY l.key
       ORDER BY l.key ASC;

Answer 3

我认为您希望licenses表作为LEFT JOIN中的第一个表，所以我认为这是您想要的查询：

SELECT l.key as "Licença",
       coalesce(sum(c."customersAmount"), 0) as "Comsumo dos ultimos 30 dias"
FROM licenses l LEFT JOIN
     consumptions c
     ON c."licenseKey" = l.key AND
        c."consumedAt" >= current_date - interval '30' day
WHERE l.label LIKE '%Casa%'
GROUP BY l.key
ORDER BY l.key ASC;

无数据时显示数字零

3 个答案: