Question

我尝试这个例子，但它不起作用。而不是具有user_login名称，而是打印“当前”字符串。我的感觉是：代码是静态执行的，因为我没有在wordpress中使用正确的插件来完成这项工作。

DROP TABLE IF EXISTS my_table;

CREATE TABLE my_table
(serial CHAR(3) NOT NULL
,date DATE NOT NULL
,value INT NOT NULL
,PRIMARY KEY (serial,date)
);

INSERT INTO my_table VALUES
('xxx','2016-01-03',12),
('xxx','2016-01-02',5),
('xxx','2016-01-01',3),
('yyy','2016-01-03',9),
('yyy','2016-01-02',6),
('yyy','2016-01-01',1);

SELECT x.* 
     , MAX(y.value) prev 
  FROM my_table x 
  LEFT 
  JOIN my_table y 
    ON y.serial = x.serial 
   AND y.date < x.date 
 GROUP 
    BY x.serial
     , x.date;
+--------+------------+-------+------+
| serial | date       | value | prev |
+--------+------------+-------+------+
| xxx    | 2016-01-01 |     3 | NULL |
| xxx    | 2016-01-02 |     5 |    3 |
| xxx    | 2016-01-03 |    12 |    5 |
| yyy    | 2016-01-01 |     1 | NULL |
| yyy    | 2016-01-02 |     6 |    1 |
| yyy    | 2016-01-03 |     9 |    6 |
+--------+------------+-------+------+

如何知道用户登录javascript wordpress

0 个答案: