mysql的SQL语句求..急

select sum(count) from (--一级 select count(*) as count from table_name where pid= 'id'union all --二级 select count(*) as count from table_name t1 inner join table_name t2 on t1.pid = t2.id where t2.pid= 'id'union all --三级 select count(*) as count from ...

SELECT a.* from tb_take_statistics as a JOIN (SELECT userName ,count(userName) as count FROM tb_take_statistics GROUP BY `userName `) as b on a.userName = b.userName ORDER BY b.count desc,b.userName asc

select * from apublishingtask where thepublisher=去标示符串 and complete=完成 and time>DATE_ADD(NOW(),INTERVAL -30 DAY);

SELECT substr(target.dateTIme, 1, 7),userInfo.name,typeInfo.typeName,target.num FROM target LEFT JOIN userInfo on userInfo.ID = target.userID LEFT JOIN typeInfo ON typeInfo.ID = target.typeID ORDER BY substr(target.dateTIme, 1, 7) DESC, userInfo.ID, typeInfo.ID 即可 ...

这个问题和设计有关系, 简单的sql优化提升不了多少, 但是这个sql还是可以进一步优化的 利用索引, 用union all代替in, 如 select * from tab where id in (1,2), 可写成select * from tab where id = 1 union all select * from tab where id = 2 但是上面的优化起不到根本效果, 如果100...

要查询 MySQL 数据库中表的索引信息，可以使用以下 SQL 语句： `SHOW INDEX FROM 表名;` 其中，`表名` 需替换为要查询的表的名称。执行此 SQL 语句后，系统会返回一个表格，该表格包含了表的每个索引的详细信息。例如，你可以了解到索引的名称、类型（如 BTree、Hash 或全文索引）、索引所涉及的...

INSERT INTO `TEST` (`id`, `uid` , `regdate` , `remark`) VALUES (1,'张三','2008-07-02','学生');INSERT INTO `TEST` (`id`, `uid` , `regdate` , `remark`) VALUES (2,'李四','2008-07-02','学生');...一个一个的插入 ...

SELECT o1.order_id,MAX(o1.subtotal) AS 订单总金额,SUM(o2.cost) AS 订单明细合计 FROM `order` o1 JOIN order_details o2 ON (o1.order_id = o2.order_id)GROUP BY o1.order_id HAVING MAX(o1.subtotal) <> SUM(o2.cost)...

MYSQL 数据库SQL语句写法如下：select login_name, count(*) as counts from loginlogs group by login_name order by counts desc limit 0,10 MSSQL 或Access数据库SQL语句写法如下：select top 10 login_name, count(*) as counts from loginlogs group by login_name order by counts desc ...

使用MySQL实现已知每日产量求月累计数，可以使用窗口函数和子查询来实现。具体步骤如下：创建测试表格并插入数据 首先，需要创建一个测试表格并插入数据：CREATE TABLE production (date DATE,daily_production INT,monthly_production INT);INSERT INTO production (date, daily_production) VALUES('2023-01-...