Relational Database Keyword Retrieval Based On Index Structure

With the deepening of computer applications in the field of management, a large amount of data is stored in the relational database, how quickly, efficiently and especially retrieve from a plurality of interconnected databases is a hot research field of database search problem in recent years. Early database retrieval mainly face the few professional users, professional users can directly write query statements or program to retrieve the data needed from the database, but for the average user to retrieve data from the database using database query commands is unrealistic and inconvenience, that also will severely restrict the public database role to play. Keyword-based relational database retrieval methods will facilitate general users, users do not understand the database structure, and not have to master database query language, they can enter keywords to retrieve data needed from the database, this is similar to using the search engines to search the web data.Based on the keyword retrieval in relational database, this paper has proposed a new retrieval method. The main work is as follows.First a database indexing structure that has recorded all the position of each data item in the data tables and fields is built, and a main-foreign key relationship table that used to describe relationships between each data table on the basis of database diagram is built.The retrieval system judges whether the tables which contain multiple words could be established relationship according to indexing structure and main-foreign key relationship table, if the relationship could be established, then the retrieval system automatically constructs multiple tables join query command to query and output records that is associated with multiple keywords and records that contain the keywords, or it just outputs the records that contains the keywords. And the queried results will be ordered on the basis of the relevance of keywords and queried results.In order to further improve the efficiency of retrieval, a queried results storage structure has been built, and the queried keywords and corresponding results are stored into it. When a user enters keywords to retrieve, retrieval system retrieves in the storage structure first, if results can be retrieved, it will output the results and no longer access index structure. Otherwise, it builds SQL commands by index structure and main-foreign key relationship table to search in original database.The experiment shows that the retrieval mechanism of keyword retrieval of relational database that based on index structure and queried results storage structure has nice performance in efficiency, recall and precision.