如何设计高效合理的查询语句

How to design reasonable and efficient query

数据库系统是管理信息系统的核心,基于数据库的联机事务处理(OLTP)以及联机分析处理(OLAP)是银行、企业、政府等部门最为重要的计算机应用之一。从大多数系统的应用实例来看,查询操作在各种数据库操作中所占据的比重最大,而查询操作所基于的SELECT语句在SQL语句中又是代价最大的。

The database system is the core of management information systems,database-based online transaction processing (OLTP) and online analytical processing (OLAP) is a banking,business,government and other departments of the most important one of computer applications. From the application of most systems,the query operation in a variety of database operations in the largest occupied,and the query operation is based on the SELECT statement in the SQL statement is the biggest price.