Database Reference
In-Depth Information
can also add a comment to the end of a line of code by placing the
hyphens after all executable code.
Single-Line Comments
. Precede a line with the REM or REMARK
keyword to mark that line as a comment.
The following query demonstrates all three types of comments. See the
result in Figure 18.28.
REM This query looks for Artists with
REM a letter "a" in their names.
SELECT
/* Ignore this line
and this line
and this line too
*/
NAME
--this is the FROM clause
FROM ARTIST
WHERE NAME LIKE '%a%' --and this is the WHERE clause
;
In a color graphic, the comments would be highlighted in red within
SQL*Plus Worksheet. This makes them much easier to see. I have high-
lighted commented sections by boxing them, as shown in Figure 18.28.
The penultimate section in this chapter on tables will examine the recy-
cle bin, which is newly introduced in Oracle Database 10
g
.
18.7
The Recycle Bin
Oracle Database 10
g
introduces a recycle bin. This feature is certainly use-
ful from the perspective of database administration, but it could cause
problems with space and perhaps performance if the recycle bin is not regu-
larly monitored and cleared. There are several changes to various DDL
commands associated with the recycle bin as listed below. The syntax dia-
gram in Figure 18.29 shows generally applicable recycle bin syntax.
The DROP TABLE command now requires a PURGE option if an
object is not to be retained in the recycle bin.
