SELECT TABLE_NAME,TABLE_ROWS,DATA_LENGTH/1024/1024 DATA_LENGTH,CREATE_TIME,TABLE_COLLATION FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'lir' ORDER BY TABLE_ROWS DESC [dss@localhost ~]$ mysql -u root -p Enter password: Welcome to th
SELECT TABLE_NAME,TABLE_ROWS,DATA_LENGTH/1024/1024 "DATA_LENGTH",CREATE_TIME,TABLE_COLLATION FROM
INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'lir' ORDER BY TABLE_ROWS DESC
[dss@localhost ~]$ mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 36 Server version: 5.6.16 MySQL Community Server (GPL) Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> show database; ERROR 1064 (42000): 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 'database' at line 1 mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | fire | | hive | | lir | | mysql | | performance_schema | | test | +--------------------+ 7 rows in set (0.03 sec) mysql> use fire; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> load data infile 'aa.txt' into table firewallb; ERROR 13 (HY000): Can't get stat of '/var/lib/mysql/fire/aa.txt' (Errcode: 2 - No such file or directory) mysql> load data infile '/home/dss/aa.txt' into table firewallb; ERROR 13 (HY000): Can't get stat of '/home/dss/aa.txt' (Errcode: 13 - Permission denied) mysql> load data infile '/tmp/aa.txt' into table firewallb; Query OK, 10 rows affected (0.07 sec) Records: 10 Deleted: 0 Skipped: 0 Warnings: 0 mysql> load data infile '/tmp/fireb.txt' into table firewallb;
Query OK, 16600931 rows affected (38 min 25.54 sec) Records: 16600931 Deleted: 0 Skipped: 0 Warnings: 0
导入数据文件到mysql
mysql导出数据到文件
SELECT * INTO OUTFILE '/tmp/bb.csv' FIELDS TERMINATED BY ',' LINES TERMINATED BY '\r\n' FROM bb_month;

How to effectively monitor MySQL performance? Use tools such as mysqladmin, SHOWGLOBALSTATUS, PerconaMonitoring and Management (PMM), and MySQL EnterpriseMonitor. 1. Use mysqladmin to view the number of connections. 2. Use SHOWGLOBALSTATUS to view the query number. 3.PMM provides detailed performance data and graphical interface. 4.MySQLEnterpriseMonitor provides rich monitoring functions and alarm mechanisms.

The difference between MySQL and SQLServer is: 1) MySQL is open source and suitable for web and embedded systems, 2) SQLServer is a commercial product of Microsoft and is suitable for enterprise-level applications. There are significant differences between the two in storage engine, performance optimization and application scenarios. When choosing, you need to consider project size and future scalability.

In enterprise-level application scenarios that require high availability, advanced security and good integration, SQLServer should be chosen instead of MySQL. 1) SQLServer provides enterprise-level features such as high availability and advanced security. 2) It is closely integrated with Microsoft ecosystems such as VisualStudio and PowerBI. 3) SQLServer performs excellent in performance optimization and supports memory-optimized tables and column storage indexes.

MySQLmanagescharactersetsandcollationsbyusingUTF-8asthedefault,allowingconfigurationatdatabase,table,andcolumnlevels,andrequiringcarefulalignmenttoavoidmismatches.1)Setdefaultcharactersetandcollationforadatabase.2)Configurecharactersetandcollationfor

A MySQL trigger is an automatically executed stored procedure associated with a table that is used to perform a series of operations when a specific data operation is performed. 1) Trigger definition and function: used for data verification, logging, etc. 2) Working principle: It is divided into BEFORE and AFTER, and supports row-level triggering. 3) Example of use: Can be used to record salary changes or update inventory. 4) Debugging skills: Use SHOWTRIGGERS and SHOWCREATETRIGGER commands. 5) Performance optimization: Avoid complex operations, use indexes, and manage transactions.

The steps to create and manage user accounts in MySQL are as follows: 1. Create a user: Use CREATEUSER'newuser'@'localhost'IDENTIFIEDBY'password'; 2. Assign permissions: Use GRANTSELECT, INSERT, UPDATEONmydatabase.TO'newuser'@'localhost'; 3. Fix permission error: Use REVOKEALLPRIVILEGESONmydatabase.FROM'newuser'@'localhost'; then reassign permissions; 4. Optimization permissions: Use SHOWGRA

MySQL is suitable for rapid development and small and medium-sized applications, while Oracle is suitable for large enterprises and high availability needs. 1) MySQL is open source and easy to use, suitable for web applications and small and medium-sized enterprises. 2) Oracle is powerful and suitable for large enterprises and government agencies. 3) MySQL supports a variety of storage engines, and Oracle provides rich enterprise-level functions.

The disadvantages of MySQL compared to other relational databases include: 1. Performance issues: You may encounter bottlenecks when processing large-scale data, and PostgreSQL performs better in complex queries and big data processing. 2. Scalability: The horizontal scaling ability is not as good as Google Spanner and Amazon Aurora. 3. Functional limitations: Not as good as PostgreSQL and Oracle in advanced functions, some functions require more custom code and maintenance.


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