[英]MySQL - Error #1064 in LEFT JOIN
我目前正在尝试仅使用MySQL查询来格式化数据。 我不想使用编程语言来操纵它。 所有操作仅在一张桌子上完成。
这是我的查询:
SELECT DATE(datetime_column) AS date, COUNT(`id`) AS users_a FROM users a
WHERE datetime_column >= '2017-12-01' GROUP BY DATE(datetime_column), rank HAVING rank = "good"
LEFT JOIN (SELECT DATE(datetime_column) AS date, COUNT(`id`) AS users_b FROM users
WHERE datetime_column >= '2017-12-01' GROUP BY DATE(datetime_column), rank HAVING rank = "bad") AS b
ON b.date = a.date;
输出应类似于:
date users_a users_b 2017-12-01 17 20 2017-12-02 4 9
如果两个查询分别执行,则它们将给出准确的结果,我只希望数据位于一个表中。 但是,出现以下错误:
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'LEFT JOIN (SELECT DATE(datetime) AS date, COUNT(`id`) AS users_b FROM ' at line 2
尝试这个
SELECT DATE(datetime_column) date, SUM(CASE WHEN rank = "good" THEN 1 END) users_a, SUM(CASE WHEN rank = "bad" THEN 1 END) users_b
FROM users
WHERE datetime_column>= '2017-12-01'
GROUP BY DATE(datetime_column)
JOINs
必须在HAVING
子句之前发生。
根据MySQL SELECT
文档 :
SELECT
[ALL | DISTINCT | DISTINCTROW ]
[HIGH_PRIORITY]
[STRAIGHT_JOIN]
[SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT]
[SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS]
select_expr [, select_expr ...]
[FROM table_references
[PARTITION partition_list]
[WHERE where_condition]
[GROUP BY {col_name | expr | position}
[ASC | DESC], ... [WITH ROLLUP]]
[HAVING where_condition]
[ORDER BY {col_name | expr | position}
[ASC | DESC], ...]
[LIMIT {[offset,] row_count | row_count OFFSET offset}]
[PROCEDURE procedure_name(argument_list)]
[INTO OUTFILE 'file_name'
[CHARACTER SET charset_name]
export_options
| INTO DUMPFILE 'file_name'
| INTO var_name [, var_name]]
[FOR UPDATE | LOCK IN SHARE MODE]]
另外,您还可以将其简化为:
SELECT
DATE(`datetime_column`) AS `date`,
SUM(IF(`rank` = 'good', 1, 0)) AS `users_a`,
SUM(IF(`rank` = 'bad', 1, 0)) AS `users_b`
FROM
`users`
WHERE
datetime_column >= '2017-12-01'
GROUP BY
DATE(datetime_column)
这递增users_a
每一个“好”用户栏, users_b
每一个“坏”。
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