Database Reference
In-Depth Information
Figure 18.24
TRUNCATE
Command Syntax.
You cannot use a WHERE clause filter with a TRUNCATE com-
mand like you can with a DELETE command. Thus TRUNCATE
will always delete all rows from a table.
You can use the TRUNCATE command to remove all rows from the
table NEW_RELEASES_FOR_2001 as shown following:
TRUNCATE TABLE NEW_RELEASES_FOR_2001;
Note:
TRUNCATE is a DDL command. All DDL commands commit
changes automatically, instantly upon completion. TRUNCATE is not
reversible!
Now let's examine adding comments to tables.
18.6
Adding Comments to Tables
Comments can also be called remarks. As their name implies, comments are
informational text added to either a script or a schema object. Comments
can be included in both SQL and PL/SQL scripts and can be attached to
schema objects.
18.6.1
Adding Comments to Schema Objects
See the syntax diagram in Figure 18.25 for details on adding comments to
database schema objects, such as tables and table columns.
Let's add some brief comments to some of the tables in the MUSIC
schema.
