Database, DBMS and SQL
The database is a collection of data, which consists of one or more tables. The data description of one class object is stored in each table, and a typical expression is shown in Table 10.1. Each column of the table describes an attribute of an object, such as a name, birth year, etc., and each line of the table is a specific description of an object. Generally, a line in the table is called record (ROW), and each column of the table is referred to as a field (Column). Databases typically also include some additional structures for maintenance data.
Table 10.1
Licena's name of the birth year gender 1 Li Ming 06/12/77 male 2 Zhang Fang 11/24/78 female
If there is only one table of a database, it is called a simple database. If the database consists of multiple related tables, it is called a relational database. The relational database uses the public key field to link its table, for example, in Table 10.1, you can use a key field as a key field. If there is a student transcript table in the database, you can pass the school number. This key field links two tables.
DBMS (Database Management System) is a set of programs for defining, managing, and processing relationships between databases and applications, such as FoxPro, Access, Sybase, etc. are DBMS. Figure 10.1 illustrates the relationship between the user, DBMS, and the database.
Figure 10.1 Relationship between users, DBMS, database
SQL (Structured Query Language, Structured Query Language) The earliest is proposed by IBM, which is a text-based language specifically used to process the relational database. SQL provides a perfect and consistent interface to the database. It is not a stand-alone computer language that requires the support of DBMS to perform. SQL is a standard database language, and most of the DBMS supports it.
