Structured query language is abbreviated as SQL (pronunciation:/? Es kju el/ "S-Q-L ") is a special programming language, a database query and programming language, which is used to access data, query, update and manage relational database systems; It is also an extension of the database script file.
Structured query language is an advanced non-procedural programming language, which allows users to work on advanced data structures. It does not require users to specify the storage mode of data, nor does it require users to know the specific storage mode of data, so different database systems with completely different underlying structures can use the same structured query language as the interface for data input and management. Structured query language statements can be nested, which makes it very flexible and powerful.
1986 10, the American National Standards Institute standardized SQL and became the standard language of relational database management system (ANSI X3. 135- 1986) and became an international standard in 1987 with the support of the international organization for standards. However, various popular database systems have made some modifications and extensions to the SQL specification in practice. Therefore, in fact, SQL between different database systems is not completely universal.