Module 02b - Basic SQL - Part I/II

Question 1

SELECT statement

Answer 1

SELECT [Column]
FROM [Table]
WHERE [condition];

Question 2

How to eliminate duplicates

Answer 2

SELECT DISTINCT

Question 3

Which are the the characteristics of WHERE clause

Answer 3

• Case sensitive constants
• Is a optional clause
• Admits conjunction with ‘AND’ and ‘OR’ operators

Question 4

How to sort results

Answer 4

With the clause ‘ORDER BY’

Question 5

How to change ascending and descending order

Answer 5

Using ASC ou DESC, as following:

ORDER BY [Column] DESC, [Column] ASC

Question 6

Which options WHERE clause has?

Answer 6

AND to add more than one condition
OR to admit one condition OR another
IN to look for a condition of a sub-conjunct
NOT IN to negate a condition of sub-conjunct
BETWEEN to establish ranges
Math symbols
LIKE that admits wildcards _ or % (SQL 92)

Question 7

Which built-in Functions SQL has

Answer 7

COUNT - counts the amount of rows
SUM - sums the values of a column
AVG - returns the average value of a column
MIN - returns the minimum value of a column
MAX - returns the maximum value of a column

Question 8

Is it possible to make arithmetic calculations between columns?

Answer 8

Yes. By using statements like:
SELECT [Column1] * [Column2] AS Result…
SELECT [Column1] / [Column2] AS Result…
SELECT [Column1] + [Column2] AS Result…
…

Question 9

How to return String Functions on Oracle SQL

Answer 9

Using concatenation symbols and character strings between simple coma, e.g.:
SELECT [Column1] || ‘ made of ‘ || [Column2]

Question 10

How to group results from a report?

Answer 10

Using the SQL keyword ‘GROUP BY’

Question 11

How to state GROUP BY keyword?

Answer 11

WHERE is placed before GROUP BY

Question 12

How restrict grouped results

Answer 12

Using HAVING operator

Question 13

How to eliminate a ambiguity when using HAVING operator

Answer 13

By always applying WHERE clause before HAVING operator, just for sure