You can’t specify target in MySQL The error of table for update in FROM clause means that you cannot select some values in the same table first, and then update this table (in the same statement)
Category: Database
The database is a warehouse that organizes, stores and manages data according to the data structure. It was created more than 60 years ago. With the development of information technology and the market, especially after the 1990s, data management is no longer just It is to store and manage data, and transform it into various data management methods required by users. There are many types of databases, from the simplest tables that store various data to large-scale database systems that can store massive amounts of data. They have been widely used in all aspects.
MySQL backup file. XB database backup restore
Today an old friend told me that his mysql backup file suffix .xb could not be restored, or it was restored with only tables without data, so I decided to try I did a backup and restore, and I sear
MySQL supported data type
Data types supported by mysql Integer ”’ Type tinyint: 1 byte, value range -128~127, default length 4 smallint: 2 bytes, value range -32768 ~ 32767, default length 6 mediumint: 3 bytes int: 4 byte
MySQL data type
Data types are the basic rules that define what data can be stored in a column and how the data is stored
When designing a table, you should pay special attention to the data type used. Using the
MySQL master from mount
1. Modify the my.cnf file
vim /etc/my.cnf 1.1 Main Library< /p> #The current mysql service number is 1, which is the first mysql server
server-id=1
#Binary log file
log-bin=mysql-bin
1
PowerDesigner16.5 attached the Name field in Comment and generates SQL
1. Attach the value of the name field to the comment comment
The first step: the program to be executed
‘******************************** **********************************************’
Questions about PowerDesigner export SQLServer 2008 table structure
We often use the reverse engineering of PowerDesigner to export the table structure of the database, like exporting the table structure of the Oracle database, we use the client connection method.
The physical model of the PowerDesigner design table selects comments and defaults, non-empty
You need to choose this by yourself, and it won’t be there by default
Basic tutorial: http://jingyan.baidu.com/article/bea41d43684fa4b4c51be6cf.html
http://jingyan.baidu.com/article/3ae
How can PowerDesigner can change when Code is not automatically followed when the field name of the modified table
Reproduced from: http://blog.csdn.net/hongqishi/article/details/7050255
How can the Code not automatically change when the table field Name is modified tools-> General Options-> Dialog:Operation Modes:
Remove the √ in front of NameToCodeMirroring
SQLITE3 database
1. SQLite3 database SQLite3 can be integrated with Python using the sqlite3 module. Generally, python 2.5 and above have their own sqlite3 module by default, so users do not need to download it separately.
So, first create a database The connection object, the connection object, the syntax is as follows: