Sams Teach Yourself SQL in 24 Hours, Third Edition By Ronald R. Plew, Ryan K. Stephens
Table of Contents
Hour 7. Introduction to the Database Query
Q&A
Q1:
Why won't the SELECT clause work without the FROM clause?
A1:
The SELECT clause merely tells the database what data you want to see. The FROM clause tells the database where to get the data.
Q2:
When I use the ORDER BY clause and choose the option descending, what does that really do to the data?
A2:
Say that you use the ORDER BY clause and have selected the last_name from the EMPLOYEE_TBL. If you used the descending option, the order would start with the letter Z and finish with the letter A. Now, let's say that you have used the ORDER BY clause and have selected the salary from the EMPLOYEE_PAY_TBL. If you used the descending option, the order would start with the largest salary down to the lowest salary.
Q3:
What advantage is there to renaming columns ?
A3:
The new column name could fit the description of the returned data more closely for a particular report.
