Oracle SQL Jumpstart with Examples- P10: Review "As a consultant with more than 12 years of experience working with Oracle databases on a daily basis, reviewing this book was a unique and enjoyable experience. The SQL language is without doubt one of the most critical database skills and it is best learned by example. This book addresses that crucial need. Mr. Powell does an excellent job of clarifying the concepts by using meaningful and easy to understand examples. Frankly, I have not come across any other book on SQL that is as good a compilation of SQL concepts in a single. | 420 The Recycle Bin 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 . 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 highlighted commented sections by boxing them as shown in Figure . The penultimate section in this chapter on tables will examine the recycle bin which is newly introduced in Oracle Database 10 . gfjBThe Recycle Bin Oracle Database 10 introduces a recycle bin. This feature is certainly useful from the perspective of database administration but it could cause problems with space and perhaps performance if the recycle bin is not regularly monitored and cleared. There are several changes to various DDL commands associated with the recycle bin as listed below. The syntax diagram in Figure 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. Please purchase PDF Split-Merge on to remove this watermark. Metadata Views 421 Figure Commenting SQL Code. The new PURGE command is required to allow clearing the recycle bin. The Oracle Database 10g SQL Reference Manual states that the FLASHBACK TABLE command is used to recover a table from the recycle bin. This chapter concludes with a short section on database metadata as directly applicable to this chapter. Metadata Views This section lists metadata views allowing access into the structural details of tables. Chapter 19 describes .
