Basic knowledge of the database

1. Database system = Database management system (Tools for managing databases) (Dbms,database Management System) + database + Administrator

2. Database concept: An efficient solution for managing a large amount of information, to organize, store, and manage the library of data according to its data structure. 3. Professional database: Oracle, DB2, SQL Server, My SQL. of These, My SQL is the most popular, Eng strong enough to handle Web applications. 4.Oracle Company Name: Oracle Corporation. 5. It is a relational database. The database system is built on the relational model. Relational Model: 1. The data structure can stipulate that the same kind of information, the structure is consistent, is a two-dimensional table;2. The relationship between data can be set. The linkages between entities. Example: How the entity structure should be handled when the entity (student) in daily life, and the attribute of the entity (student's number, name) are saved to the database. so it is also called a two-dimensional table model. 6. A non-relational database system, not a two-dimensional table, is a key-value logarithmic column. Eg:mongodb, Membase. 7. Object Type database: Object Relational mapping. 8. Typical concepts of relational databasesdatabase: The warehouse of the data. A collection of saved data. table: Data is saved in a table, and data stored in a table should have the same data format. line: Used to record data. columns: Used to specify the data format. record: The data in the row. field: A column of data. The rows and columns are based on the data structure, and the records and fields are based on the information. *****************************************************************************

Data type:

integral type data:

bigint (Long integer number): integer data (all numbers) from -2^63 (-9223372036854775808) to 2^63-1 (9223372036854775807). The storage size is 8 bytes.

int (Base integer number): Integer data (all numbers) from -2^31 (-2,147,483,648) to 2^31–1 (2,147,483,647). The storage size is 4 bytes. The SQL-92 synonymous word for int is integer.

smallint (short integer number): Integer data from -2^15 (-32,768) to 2^15–1 (32,767). The storage size is 2 bytes.

Tinyint: Integer data from 0 to 255. The storage size is 1 bytes.