Sams Teach Yourself SQL in 21 Days, Fourth Edition

Q&A

Q1:	Why should I spend valuable time learning SQL*Plus when I can achieve the same results using standard SQL?
A1:	If your requirements for reports are simple, standard SQL is fine. But you can reduce the time you spend on reports by using SQL*Plus. And you can be sure that the people needing your reports will always want more information.
Q2:	How can I select SYSDATE from the DUAL table if it is not a column?
A2:	You can select SYSDATE from DUAL or any other valid table because SYSDATE is a pseudocolumn.
Q3:	When using the DECODE command, can I use a DECODE within another DECODE?
A3:	Yes, you can DECODE within a DECODE. In SQL, you can perform functions on other functions to achieve the desired results.