Question

使用CTE我尝试

WITH cte as ( 
     SELECT myFieldName, 
            row_number() over (order by gps_device_id) as rn
     FROM tracker.gps_devices
) 
UPDATE cte
SET cte.myFieldName = CASE WHEN cte.rn % 3  = 0  THEN '0'
                           WHEN cte.rn % 3  = 1  THEN '1'
                           WHEN cte.rn % 3  = 2  THEN '2'
                       END

但是出现了以下错误。

错误：关系“cte”不存在

看起来INSERT DELETE WITH UPDATE但只有{c}内的UPDATE tracker.gps_devices g SET g.myFieldName = CASE WHEN t.rn % 3 = 0 THEN '0' WHEN t.rn % 3 = 1 THEN '1' WHEN t.rn % 3 = 2 THEN '2' END FROM (SELECT gps_device_id, myFieldName, row_number() over (order by gps_device_id) as rn FROM tracker.gps_devices) as t WHERE g.gps_device_id = t.gps_device_id，这是正确的吗？我确定我做过这样的事情，但也许是在不同的数据库中。

https://www.postgresql.org/docs/9.6/static/queries-with.html

所以我以此结束，即使工作很混乱，有什么建议吗？

router.get('/service/products/all', function(req, res, next) {
    Product.find({ 'PMC18': {$ne: null} }, { prodCode: 1, prodName: 1, description: 1, PMC18: 1, inStock: 1 }, function (err, docs) {
        console.log(err);        
        console.log(docs);
        res.json(docs);
    }).limit(50);    
});

Answer 1

您可以使用cte进行更新，例如（假设id是主键）：

with cte as ( 
    select 
        id, 
        my_field_name, 
        row_number() over (order by gps_device_id) as rn
    from gps_devices
) 
update gps_devices
set my_field_name = (rn % 3)::text
from cte
where gps_devices.id = cte.id;

您可以插入，更新或删除表（视图）的行，而不是查询的结果集。

我可以更新cte吗？

1 个答案: