SQL query in the in, exists, not in, not exists usage and difference, sqlexists
1. in and exists
In connects the External table to the internal table as a hash (Dictionary set), while exists loops the External table and queries the internal table
Usage and difference of in, exists, not in, and not exists in SQL queries
1. in and exists
In connects the External table to the internal table as a hash (Dictionary set), while exists loops the External table and queries the internal table after
Backup features:
A quick copy of the file, which can only run on the machine where the database directory is located, perform lock tables and UNLOCK tables online, and restore with only copy backup files to source directory coverage.
Insufficient:
Problems occurred during MySQL installation: bitsCN.com
Problems during MySQL installation
1> decompress MySQL
[html] [root@localhost test]# tar -xvf MySQL-5.6.12-2.linux_glibc2.5.i386.rpm-bundle.tar
MySQL常用指令,java,php程序员,数据库工程师必备。程序员小冰常用资料整理MySQL common commands (for reference)The most common display commands are:1. Display the list of databases.show databases;2. Display the data table in the library:Use MySQL;Show tables;3, display the
How to configure MySQL database server on CentOS
BitsCN.com accidentally found CentOS Professional Forum, remember: http://www.centospub.com
As a result, the initial learning configuration
This environment:
CentOS system,
Mysql-server (version
Problems During MySQL installation 1> decompress MySQL
[html] [root@localhost test]# tar -xvf MySQL-5.6.12-2.linux_glibc2.5.i386.rpm-bundle.tar MySQL-test-5.6.12-2.linux_glibc2.5.i386.rpm MySQL-shared-5.6.12-2.linux_glibc2.5.i386.rpm MySQL-
Similarly, using the goods table to practice subqueries, the table structure is as follows:All data (cat_id associated with category.cat_id):Category table:Mingoods (test when connecting queries)First, sub-query 1,where sub-query: The result of the
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