mysql> select * from v_student; +---+---+---+ | id | NAME | sex | +---+---+---+ | 901 | 张老大 | 男| +---+---+---+ 1 row in set (0.03 sec) mysql> update v_student set name='张老大11'; Query OK, 1 row affected (0.02 sec) Rows matched: 1 Changed: 1 ...
ERROR 1651 (HY000): Query cache is disabled; restart the server with query_cache_type=1 to enable it 1. 2. 查了下报错原因: query_cache_type参数需要动态编译开启,如果用户在运行时动态关闭query cache, 会导致额外CPU的开销,即对query cache加解锁操作。在负载非常高的MySQL服务器上,这个问题变得尤为...
mysql 中有lateral view mysql parallel query MYSQL的INNODB存储引擎的索引是遵循最左匹配规则的,索引的优劣有你的SQL有直接的关系,一个好的SQL和一个好的索引,MYSQL单表都可以支持5000w~8000w左右的数据,平时开发的过程中可以用关键字Explain关键字解释你的SQL执行计划: explain select * from user where id = ...
I made quite a complex View on my MySQL database, and I realized that some queries are slow. My first idea was to add indexes but it's not possible to do on a view so I'm lost on how to improve the performance of my query. I'll share here my View query, and I'll do my...
mysql> select * from v_student; +---+---+---+ | id | NAME | sex | +---+---+---+ | 901 | 张老大 | 男 | +---+---+---+ 1 row in set (0.03 sec) mysql> update v_student set name='张老大11'; Query OK, 1 row affected (0.02 sec) Rows matched: 1 Changed: 1...
问如何在c#中将DataGridView多行数据保存到MySQL数据库中EN一种方法是使用Foreach循环逐个获取DataGridView...
3 rows in set (0.00 sec) 更新: mysql> CREATE VIEW stu_view2 AS SELECT id, name FROM students; Query OK, 0 rows affected (0.01 sec) 验证: mysql> select * from stu_view2; +---+---+ | id | name | +---+---+ | 1 | ...
Data can be gathered directly from MySQL Server without additional configuration, using a MySQL Enterprise Monitor Agent For more information on the Query Analyzer user interface, see Section 32.3, “Query Analyzer User Interface”. Once the data is collected, you view and monitor the queries, ...
a condition in the outer query that could significantly reduce amount of data needed to be processed by subquery can be applied too late - server has to materialize a large derived table first, and use the restrictive condition when reading from this materialized derived table. Obviously, this ...
I have a query which works as expected in the querybrowser, but when made as a view produces undesired results. The Query (correct results): SELECT H.LocationCode, H.ProjectCode, H.Work_ID, MAX(H.`Week`) AS `Week`, SEC_TO_TIME(SUM(H.Tijd)) AS `Tijd` ...