Question

我可以拥有2个表连接结果的别名吗？这样我就可以用别名来调用表的结果。

SELECT emp_table.Name, dept_table.dept
FROM dept_table
inner join emp_table
on emp_table.dept_id = dept_table.dept_id;

Answer 1

您可以使用子查询：

Track = function (trackId){

    var currentTrack = "";

   SC.initialize({

        client_id: "17a992358db64d99e492326797fff3e8"
    });

    SC.stream("http://api.soundcloud.com/tracks/" + trackId, function(sound){
        currentTrack = sound;
    });

    this.play = function() {
        currentTrack.play();
    };

    this.pause = function() {
        currentTrack.pause();
    };

    this.stop = function() {
        currentTrack.stop();
    };
};

Rotation = function(tracks) {
    var currentTrack = tracks[0];

    this.currentTrack = function () {
        return currentTrack;
    };
};

$(document).ready (function(){
    var songs = [{"soundcloud_id":"108816655"},{"soundcloud_id":"79408289"}]
    var rotation = new Rotation(songs);
    var currentTrack = rotation.currentTrack();
    var currentPlayingTrack = new Track(currentTrack.soundcloud_id);

    $('#play').on('click', function(event){
        currentPlayingTrack.play();
        $('#pause').show();
        $('#play').hide();
    });

    $('#pause').on('click', function(event){
        currentPlayingTrack.pause();
        $('#pause').hide();
        $('#play').show();
    });

    $('#stop').on('click', function(event){
        currentPlayingTrack.stop();
        $('#pause').hide();
        $('#play').show();
    });        
});

或使用CTE：

SELECT YourAlias.Name
      ,YourAlias.dept
FROM (SELECT emp_table.Name, dept_table.dept
      FROM dept_table
      INNER JOIN emp_table
        on emp_table.dept_id = dept_table.dept_id) AS YourAlias;

有关CTE here的更多信息。

Answer 2

只需输入派生表：

select dt.Name, dt.dept
from
 (
   SELECT emp_table.Name, dept_table.dept
   FROM dept_table
   inner join emp_table
   on emp_table.dept_id = dept_table.dept_i
 ) dt;

Answer 3

不完全但假设列别名和表别名如此

SELECT e.Name as aliasname, d.dept as aliasdept
FROM dept_table d
inner join emp_table e
on e.dept_id = d.dept_id;

Answer 4

在SQL Server和许多其他DBMS中，您可以将连接查询包装在括号中，并在右括号后添加别名。

select joined.foo
from
(
select a.foo, b.bar
from
table1 a
inner join
table2 b
on a.baz = b.baz
) joined

我可以为内连接的结果表提供别名

4 个答案: