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您的SQL语法有错误;查看与您的MariaDB服务器版本对应的手册，以便在$sql = SELECT `id`, `email`, `avatar`,`fullname`, SUM(result) as sum_result, SUM(total) as sum_total, COUNT(rank) as `top_1` where `itq_exam_thread_test`.`rank` = 1, COUNT(rank) as `top_2` where `itq_exam_thread_test`.`rank` = 2, COUNT(rank) as `top_3` where `itq_exam_thread_test`.`rank` = 3 GROUP BY userid_created ORDER BY sum_result DESC, sum_rate DESC LIMIT 0, 100';附近使用正确的语法。itq_exam_thread_test = 1，

Answer 1

WHERE是整个查询的子句，而不是SELECT子句中的修饰符。你想要的是条件聚合。在MySQL中，执行计数非常简单，因为它将布尔表达式视为数字上下文中的整数。因此，您可以使用SUM()：

SELECT id, email, avatar, fullname, SUM(result) as sum_result,
       SUM(total) as sum_total,
       SUM(rank = 1) as top_1,
       SUM(rank = 2) as top_2,
       SUM(rank = 3) as top_3
FROM itq_exam_thread_test
GROUP BY userid_created
ORDER BY sum_result DESC
LIMIT 0, 100;

我从sum_rate中删除了ORDER BY，因为它未定义。

从多个表中选择计数并分组

1 个答案: