最近几年来，地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持，如城市管理、区划、环境整治等等，地理信息成为信息时代重要的组成部分之一； “数字地球”概念的提出，更进一步推动了作为其技术支撑的GIS的发展。 与此同时，一些学者致力于相关的理论研究，如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面，并且这两个方面构成了相互促进的发展过程。
SQLite’s DETACH DATABASE Statement is used to separate and detach a named database from a database connection, which was previously attached using an ATTACH statement. If more than one alias has been attached to the same database file, the DETACH command will only disconnect the given name, while the rest are still valid. You can’t separate. main Or temp Database.
If the database is in memory or a tempdb, the database will be destroyed and the contents will be lost. The basic syntax of the DETACH DATABASE ‘Alias-Name’ statement for SQLite is as follows: Here, ‘Alias-Name’ is the same alias you used to attach the database using the ATTACH statement. Assuming that you have created a database in the previous section and attached the ‘test’ and’ currentDB’, using .database commands, we can see: Now, let’s try to separate ‘currentDB’ from the testDB.db, as follows: Now, if you check the currently attached database, you will find that testDB.db is still connected to ‘test’ and’ main’. 1.9.1. Grammar ¶
DETACH DATABASE 'Alias-Name';
1.9.2. Example ¶
sqlite>.databases seq name file --- --------------- ---------------------- 0 main /home/sqlite/testDB.db 2 test /home/sqlite/testDB.db 3 currentDB /home/sqlite/testDB.db
sqlite> DETACH DATABASE 'currentDB';
sqlite>.databases seq name file --- --------------- ---------------------- 0 main /home/sqlite/testDB.db 2 test /home/sqlite/testDB.db