Optimization of SQL Query

Database performance issue has been the decision-makers and technical staff of the focus of common concern,affecting database performance is an important factor in the low-SQL query efficiency.In order to improve the implementation of database application system efficiency,from analysis of the process of query processing relational database query optimization techniques to start the discussion,pointing out that the relational database query optimization as a general principle.Optimization strategy in several studies,in time and space to improve the performance of the system,to a certain extent to improve efficiency of the query.