DROP TABLE Tips

The DROP TABLE command allows you to drop tables from your Oracle database. In this example we drop the BOOKS table that we created earlier in this chapter

DROP TABLE books;

Oracle 10g has a recycle bin, kind of a retirement home for old and dropped tables. You can recover a table that you have dropped from the recycle bin using the flashback table command as seen here:

SQL> DROP TABLE books;

SQL> FLASHBACK TABLE books TO BEFORE DROP;

Dropped a table by accident? In Oracle Database 10g the flashback table command will recover the dropped table and many of the objects associated with the dropped table. When you drop a table, some things are not recovered like bitmap join indexes (and advanced kind of index we will not cover in this book) and foreign key constraints (which we do cover in this book).

When dealing with a table that has been dropped, the flashback table command works most of the time, though the longer ago the table was dropped, the less likely it will be in the recycle bin. The recycle bin where dropped tables go is purged by Oracle from time to time based on a number of different criteria. You can see the contents of the recycle bin, including any table that you have dropped, from SQL*Plus by using the show recyclebin command:

SQL> show recyclebin;

ORIGINAL NAME RECYCLEBIN NAME OBJECT TYPE DROP TIME
---------------- ------------------------------ ------------ ------------
BOOKS BIN$D3XWKKUCQVq2EG8/vkjNDw==$0 TABLE 2005-05-30

To completely remove a table from the tablespace, we use the DROP TABLE command.

This command’s format follows:

DROP TABLE [schema.]table_name [CASCADE CONSTRAINTS]

Remember, Oracle will drop the table regardless of its contents and the drop table command will still execute, even if the table contains a zillion rows. The only time a drop table command will fail is when a table’s primary key is referenced by another table’s foreign key via a restraint clause.

To find all references the point to a specific table, see these notes on finding all references to a table.

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