sql命令SQL(Structured Query Language，结构查询语言)是一个功能强大的数据库语言。SQL通常使用于数据库的通讯。ANSI（美国国家标准学会）声称，SQL是关系数据库管理系统的标准语言。SQL语句通常用于完成一些数据库的操作任务，比如在数据库中更新数据，或者从数据库中检索数据。使用SQL的常见关系数据库管理系统有：-sql order SQL (Structured Query Language, structure Query Language) is a powerful database language. Often used in a SQL database communications. ANSI (American National Standards Institute) said, SQL is a database management system standard language. Usually SQL database for the completion of some of the operational tasks, such as updating the database data or from the database retrieval of data. The common use of SQL relational database management system are :