database table design best practices

I am a beginner of Yii2. I used Yii2 to establish a simple model to associate a y_user table used for testing in the database. However, an exception is thrown during access, and the exception code does not seem to have selected a database, however, I configured the correct database name in the configuration file, but t

Label:Problems encountered in a project: The system log is too large, and later deleted with the DELETE statement (rather slow), the results of the database log becomes very large (almost 10G), so you have to delete the database log.Method:--partial logs in the backup system--select * into #keep from Ccssystemlog WHERE logtime > ' 2011-12-31 '--truncate TABLE Ccs

Oracle Database Import and export practices There is an Oracle server that needs to be exported and imported. I have been familiar with Oracle before, but I have never studied Oracle Export and Import. Now I am in a hurry, so I have to make up the Internet. The operation result is as follows: Oracle Data Export and ImportStep 1: Create the user's tablespace and data filesLog On As an oracle user[Oracle @ or

instructor relationship, but more precisely the alias that is declared as a instructor relationship (alias). Identifiers such as T and S, which are used to rename a relationship, are referred to as the correlation name (correlation name) in the SQL standard, but are also commonly referred to as table aliases or related variables (correlation variable) or tuple variable (tuple variable).The above query can be expressed in a better way, to find out the

accessed and has a limited distribution (only or a limited number of rows have a small value), the system performance will be reduced. In this case, each time you use the query information, they must use join to obtain complete data. The join overhead is large, and frequent access will increase the overhead over time. To reduce this potential performance problem, you can use enumeration fields to store data, instead of searching tables to store data. For example, you can use enumeration fields

Abstract: The database is the foundation of the system. If you need to change the fields of the database frequently, or even modify the table and table relationship, I believe that no one will be able to cope with it several times! Because of the changes in the database str

, 10 million), the complex calculation should first be outside the database, in a file system with the C + + language calculation processing completed, the last to add to the table. This is the experience of telecom billing system design.(3) If you find that there are too many records for a table, such as more than 10

Bastion host table structure design and bastion host Table Structure DesignI. bastion host table structure Ii. Create a table #-*-Coding: UTF-8-*-from sqlalchemy. ext. declarative import declarative_basefrom sqlalchemy import Column, Integer, String, UniqueConstraint,

MySQL database design specifications and mysql design specificationsReprinted by songdeyouxiang 1. Database naming rulesIt consists of 26 English letters (case sensitive) and 0-9 Natural Numbers (not frequently needed) with an underscore;The name must be concise and clear (the name cannot exceed 30 characters );For exa

Database model (ID-PID): A father has many children, and a child has only one father, such a structure is a tree. In a database table, the ID and PID (parent_id) are designed. A tree is stored by ID and PID. From the object-oriented design point of view, in the tree node class is not suitable for PID, a node has 1 or 0

absolutely necessary for the documentation of SQL expressions; 5 Define the standard object naming conventions. 2, table and field design　　 1) Table Design principles (1) standardization and normalization; The standardization of data helps to eliminate data redundancy in the data