增加记录:
注:null关键字与auto_increment限制条件相结合,可以为字段自动赋值;字段必须全,且一一对应;字符型用单引号;
1 mysql> insert into test values('sunshine_habit','hello_world_lyq@163.com'
2 -> ,1558888888,null);
输出:
3 Query OK, 1 row affected (0.10 sec)
查询记录:
1 mysql> select * from test where name='sunshine_habit';
2 输出:
3 +----------------+-------------------------+--------------+----+
4 | name | email | phone_number | id |
5 +----------------+-------------------------+--------------+----+
6 | sunshine_habit | hello_world_lyq@163.com | 1558888888 | 1 |
7 +----------------+-------------------------+--------------+----+
8 1 row in set (0.00 sec)
修改记录:
1 mysql> update test set name='Sam' where name='sunshine';
输出:
2 Query OK, 1 row affected (0.06 sec)
3 Rows matched: 1 Changed: 1 Warnings: 0
删除记录
1 mysql> delete from test where name='Snow White';
2 Query OK, 1 row affected (0.08 sec)

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The EXPLAIN statement can be used to analyze and improve SQL query performance. 1. Execute the EXPLAIN statement to view the query plan. 2. Analyze the output results, pay attention to access type, index usage and JOIN order. 3. Create or adjust indexes based on the analysis results, optimize JOIN operations, and avoid full table scanning to improve query efficiency.

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MySQL partitioning improves performance and simplifies maintenance. 1) Divide large tables into small pieces by specific criteria (such as date ranges), 2) physically divide data into independent files, 3) MySQL can focus on related partitions when querying, 4) Query optimizer can skip unrelated partitions, 5) Choosing the right partition strategy and maintaining it regularly is key.

How to grant and revoke permissions in MySQL? 1. Use the GRANT statement to grant permissions, such as GRANTALLPRIVILEGESONdatabase_name.TO'username'@'host'; 2. Use the REVOKE statement to revoke permissions, such as REVOKEALLPRIVILEGESONdatabase_name.FROM'username'@'host' to ensure timely communication of permission changes.


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