Databases, DBMS, and SQL-VC ++ notes

Databases, DBMS, and SQL A database is a collection of data. It consists of one or more tables. The data description for a class of objects is stored in each table. A typical table is shown in table 10.1. Each column of the table describes an attribute of an object, such as name and date of birth. each row of the table describes an object. Generally, a row in a table is called a record or row, and each column in the table is called a field or column ). The database usually includes additional structures to maintain data. Table 10.1 Student ID Last name Date of birth Gender 1 Li Ming 06/12/77 Male 2 Zhang Fang 11/24/78 Female   If a database has only one table, it is called a simple database. If a database consists of multiple related tables, it is called a relational database. Relational databases use public key fields to associate their tables. For example, in a table, the student ID can be used as a key field. If the database has a student ID table and a student ID field, you can associate two tables by using the key field "student ID. A dbms (Database Management System) is a set of programs used to define, manage, and process the connection between databases and applications. For example, Foxpro, access, and Sybase are all DBMS. The figure shows the relationship among users, DBMS, and database. Figure User,DBMSAnd Databases Structured Query Language (Structured Query Language) was first proposed by IBM and is a text-based language specifically used to process relational databases. SQL provides a complete and consistent interface to the database. It is not an independent computer language and can be executed by the DBMS support party. SQL is a standard database language, which is currently supported by most DBMS.