Write a Basic Query

Question 1

A SQL query is a request for ___________ ?

Answer 1

Information.

Update 10/30/21, 3.3

Question 2

Is SQL a declarative or imperative programming language?

Answer 2

Declarative (3.6)

We describe the result we want, but we can’t control how the result is generated. (3.6)

Question 3

Name that Clause!

List the columns that should appear in your result grid.

Answer 3

The SELECT Clause

3.5

Question 4

Name that Clause!

Specify the data sources used in your query, typically tables.

Answer 4

The FROM Clause

3.5

Question 5

What is a query also know as?

Answer 5

A SELECT Statement.

3.5

Question 6

SQL queries must be written with their clauses in what order?

Answer 6

1. SELECT
2. FROM
3. WHERE
4. GROUP BY
5. HAVING
6. ORDER BY

(3.5)

Question 7

SQL processes its clauses in what order?

Answer 7

1. FROM
2. WHERE
3. GROUP BY
4. HAVING
5. SELECT
6. ORDER BY

(3.5)

Question 8

What does the asterisk mean in the following syntax?

SELECT *
FROM TableName

Answer 8

The asterisk (*) means “all columns,” and we have not limited the rows returned.

(3.7)

Question 9

List and define the two types of comments?

Answer 9

1. Line Comments - start with a double-dash ( – ), which will cause the rest of the line to become a comment.
2. Block Comments - start with a forward-slash followed by an asterisk ( /* ), which will cause all text to be treated as a comment until it reaches an asterisk followed by a forward slash ( */ )

(3.7)

Question 10

Do comments have to be on their own line?

Answer 10

Comments can start at any point during the query, on their own line or not.

(3.7)

Question 11

How do comments provide a method of troubleshooting?

Answer 11

They can be used to temporarily disable sections of code. This can make it easier to selectively focus your attention on a certain section of code.

(3.8)

Question 12

What does it mean to “comment out” a section of code?

Answer 12

Putting a section of code in a comment enables easily re-adding the code later by uncommenting the section of code: undoing the commenting syntax.

(3.8)

Question 13

Which type of comment can be used to comment out code?

Answer 13

Both line comments and block comments can be used to comment out code.

(3.8)

Question 14

How can you control the order the results are returned?

Answer 14

By using the ORDER BY clause.

3.11

Question 15

What is the default order of the ORDER BY clause?

Answer 15

Ascending order.

3.11

Question 16

What is the ascending order for values?

Answer 16

Small to high.

Question 17

What is the ascending order for text?

Answer 17

A to Z.

Question 18

How would you reverse sort the results of the ORDER BY clause?

Answer 18

By adding DESC after the column.

Example:
SELECT *
FROM PAT_ENC
ORDER BY CONTACT_DATE DESC

(3.11)

Question 19

How would you list the columns in the ORDER BY clause?

Answer 19

ORDER BY is followed by a comma-delimited list of columns that you want to sort in order or precedence.

(3.11)

Question 20

Why would you use the SELECT TOP statement?

Answer 20

To limit results to a number of rows or a percentage of total rows.

Example:
SELECT TOP 5 * FROM PATIENT = would return five rows from the PATIENT table
SELECT TOP 1 PERCENT * FROM PATIENT = would return one percent of the rows in the PATIENT table

(8.5)

Question 21

The SELECT and SELECT TOP statements are technically different statements. However, it can be useful to think of these as the same statement where the optional TOP keyword is evaluated after what clause?

Answer 21

The ORDER BY clause.

8.5

Question 22

Where are column aliases defined?

Answer 22

In the SELECT clause.

3.14

Question 23

Why can you use column aliases in the ORDER BY clause?

Answer 23

Because column aliases are defined in the SELECT clause and the SELECT clause is processed before the ORDER BY clause.

(3.14)

Question 24

What are two ways for defining aliases?

Answer 24

1. You can use the AS keyword in a column alias to make it explicit, but it is not required.
2. If the column alias has a space in it, it must be enclosed in double quotes (SQL Server also allows [square brackets] and ‘single quotes’)

(3.14)

Question 25

Does SQL ignore whitespace?

Answer 25

Yes, so adding spaces and carriage returns makes the code more readable while maintaining functionality.

(3.15)

Question 26

Do stylistic choices have any effect on the SQL query or the results?

Answer 26

No, stylistic choices make the code more readable while maintaining functionality.

(3.15)

Question 27

How is atomic code an example of stylistic choice?

Answer 27

Atomic code means that each individual piece of code is placed on its own line making it easier to see what is happening within different sections of code and to comment out single lines.

(3.15)

Question 28

Which clause in a SELECT statement is evaluated first?

Answer 28

FROM

3.18, Review Key

Question 29

Which clause in a SELECT statement is evaluated last?

Answer 29

ORDER BY

3.18, Review Key

Question 30

What is the syntax for a block (multi-line) comment?

Answer 30

/* Comment goes 
here */

(3.18, Review Key)

Question 31

What technique can be used to rename columns in a SQL query?

Answer 31

Aliasing

3.18, Review Key