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Anonymous users2024-02-06The structure of the storage is the main basis for classifying the types of copy databases. In today's Internet, databases are usually divided into two categories, namely relational and non-relational databases.
1. Relational database refers to a database that uses a relational model to organize data, and a relational model is a data organization composed of two-dimensional tables and their connections.
2. Non-relational databases, also known as NoSQL (not only SQL), as a supplement to relational databases, can exert high efficiency and high performance in specific scenarios and characteristic problems. Common types of non-relational databases are key-value storage databases and document-oriented databases.
A key-value storage database is similar to a hash, which allows you to add, delete, and query keys, with high performance and advantages in simplicity, deployment, and high concurrency.
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Anonymous users2024-02-05The structure of the storageis the main basis for dividing database types.
The types of databases divided according to the storage structure are divided into:
Network database, relational database, hierarchical database, object-oriented database, etc.
Relational databases, such as Oracle, Db2, Sybase, MS SQL Server, Informax, and MySQL, are mainly used in business applications.
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Anonymous users2024-02-04The structure in which the data is stored is the main basis for the type of database.
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Anonymous users2024-02-03Databases are mainly divided into relational databases and non-relational databases (NoSQL).
1. Relational databases.
Relational databases, which are stored in a format that intuitively reflects the relationships between entities. Relational databases are similar to common ones, and there are many complex relationships between tables in relational databases.
Common relational databases include MySQL and SQLSer. In a lightweight or small application, using different relational databases has little impact on the performance of the system, but when building a large application, you need to select the appropriate relational database based on the business and performance requirements of the application.
2. Non-relational database (NOSQL).
Refers to a distributed, non-relational data storage system that does not guarantee to follow the ACID principle. NoSQL database technology is closely related to CAP theory and consistent hashing algorithm. NoSQL databases are suitable for application scenarios that require speed, scalability, and changeable services.
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Anonymous users2024-02-02Databases are generally divided into three categories:
Relational databases: Two-dimensional tables are the most commonly used, such as Oracle, SQL Server, DB2, and MySQL.
Hierarchical databases: The most common is the Windows system registry mesh database: I don't know about it either.
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Anonymous users2024-02-01The char()char data type is a string with a fixed length and a maximum length of the ridge. Data stored in fields with data type char is filled up to the maximum length in the form of spaces. The length is defined between 1 and 2000 bytes.
string type. number type. date type. Other data types.
There are four types of basic data types, namely: integer: byte, short, int, and long.
Floating-point type: float, double. Logical:
boolean。Character: char
The common data types for databases are as follows: Integer Data Type: The integer data type field answer is one of the most commonly used data types.
Floating-point data type: The floating-point data type is used to store decimal decimals. Floating-point data is stored in SQL Server using roundup.
Integer data type: The integer data type is one of the most commonly used types of godly data. The int(integer)int (or integer) data type stores all positive and negative integers from the power of -2 to the power of -2 to the power of -2 to the power of -1 (2,147,483,647).
MySQL data typesThere are several types of data in MySQL: (1) Numeric values are values such as 32 or 154. MySQL supports scientific notation, which consists of an integer or floating-point number followed by "e" or "e", a symbol ("+ or "-", and an integer exponent.
2. At present, there are three types of databases used in **, including soft access, mssql and mysql of sybase. They have their own advantages, and they are suitable for use in different conventions and languages. For example, most of the small and medium-sized asp** use access data stacks, and php** jujube grips mostly use mysql >>>More
The prospect of learning UI is good, and there are many training institutions, so the local people may choose to visit and understand the real teachers and educational strength of the school before making a choice. Share the general development of the UI, I hope it will be useful to you. >>>More
The deletion operation in the data is irreparable, sometimes the data in the data table may be deleted due to misoperation, or the database crashes for other reasons, and all the data is lost, especially when there is a large amount of useful data in the database, then it is impossible for you to enter the data again from the beginning, this is the role of the backup database, back up the database, when the above situation occurs, you can restore the previous database through the backup file.
Create a database.
Select the Program Management SQL Server 2008 SQL Server Management Studio command in the Start menu to open the SQL Server Management Studio window and establish a connection using Windows or SQL Server authentication. >>>More
The database is generally composed of many tables, for example, the school builds a database, which can build a student table (including the student's name, age, student number, class, date of birth), a teacher table (including the teacher's name, age, teaching class, teaching category), a report sheet (including the student's student number, and the grades of each subject), etc. These are the ways in which the files are stored in the database, and try to make sure that the items in a table are closely related and have the same attributes, if this condition cannot be met, a table must be built (the redundancy of the built table has 4 levels). In order to meet the user's query needs, we also need to make a number of views, for example, you can make a view of his items have the name of the student, age, grades of each subject, and the teacher of each subject, etc., we can also export new items according to the existing items, for the purpose of simplicity, for example, the view can add an average grade, we add different permissions and roles to each view, and provide it to different people to query to protect the security of the database. >>>More