SQLZOO Learn SQL using: SQL Server, Oracle, MySQL, DB2, and PostgreSQL. Reference: how to... How to read the data from a database. 2 CREATE and DROP How to create tables, indexes, views and other things. 3. What is the difference between logical data independence and physical data independence? Give examples Logical Data Independence: Logical data independence is the ability to modify the conceptual schema without having alteration in external schemas or application programs. Alterations in the conceptual schema may include addition or deletion of fresh entities, attributes or relationships and should be possible without having alteration to existing external schemas or having to rewrite application programs. Physical Data Independence: Physical data independence is the ability to modify the inner schema without having alteration to the conceptual schemas or application programs. Alteration in the internal schema might include. * Using new storage devices
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