Question

美好的一天。

我有一些疑问：

查询1。

SELECT 
    n.Type as Type,
    n.UserIdn as UserIdn,
    u.Username as Username,
    n.NewsIdn as NewsIdn,
    n.Header as Header,
    n.Text as Text,
    n.Tags as Tags,
    n.ImageLink as ImageLink,
    n.VideoLink as VideoLink,
    n.DateCreate as DateCreate,
FROM News n

查询2.

Select count(*) as Uplikes FROM Likes WHERE Type = 'up' AND NewsIdn='730456' 
// value NewsIdn for example

查询3。

Select count(*) as DownLikes FROM Likes WHERE Type = 'down' AND NewsIdn='730456' 
// value NewsIdn for example

我会将来自查询1 中每个行表Uplikes的{{1}}和DownLikes的查询组合在一起（每个行表News都具有唯一性值NewsIdn）。

请告诉我怎么做？

P.S。：结果我将接下来 - http://clip2net.com/clip/m264191/1389339754-clip-63kb.jpg

Answer 1

试试这个：

SELECT 
    n.Type AS TYPE,
    n.UserIdn AS UserIdn,
    u.Username AS Username,
    n.NewsIdn AS NewsIdn,
    n.Header AS Header,
    n.Text AS TEXT,
    n.Tags AS Tags,
    n.ImageLink AS ImageLink,
    n.VideoLink AS VideoLink,
    n.DateCreate AS DateCreate, 
    SUM(l.Type = 'up') Uplikes, 
    SUM(l.Type = 'down') Downlikes
FROM News n 
INNER JOIN Users u ON n.UserIdn = u.UserIdn 
LEFT JOIN Likes l ON n.NewsIdn = l.NewsIdn
GROUP BY n.id

选中此SQL FIDDLE DEMO

|  TYPE | USERIDN | USERNAME | NEWSIDN | HEADER |                      TEXT |      TAGS |      IMAGELINK | VIDEOLINK |                      DATECREATE | UPLIKES | DOWNLIKES |
|-------|---------|----------|---------|--------|---------------------------|-----------|----------------|-----------|---------------------------------|---------|-----------|
| image |  346412 |     test |  260806 |   test |                           |           | 1388152519.jpg |           | December, 27 2013 08:55:27+0000 |       2 |         0 |
| image |  108546 |    test2 |  905554 |  test2 | 1231231111111111111111111 |  123, 123 | 1388153493.jpg |           | December, 27 2013 09:11:41+0000 |       1 |         0 |
|  text |  108546 |    test2 |  270085 |  test3 |                           | 123 ,123  |                |           | December, 27 2013 09:13:30+0000 |       1 |         0 |
| image |  108546 |    test2 |  764955 |  test4 |                           |           | 1388192300.jpg |           | December, 27 2013 19:58:22+0000 |       0 |         1 |

如何结合查询？

1 个答案: