SQL - Basics

Question 1

What does the DML query/update command SELECT do?

Answer 1

Extracts data from a database table.

Question 2

What does the DML query/update command UPDATE do?

Answer 2

Updates data in a database table.

Question 3

What does the DML query/update command DELETE do?

Answer 3

Deletes data from a database table.

Question 4

What does the DML query/update command INSERT INTO do?

Answer 4

Inserts new data into a database table.

Question 5

What does DML stand for?

Answer 5

Data Manipulation Language

Question 6

What does the DDL query/update command CREATE TABLE do?

Answer 6

Creates a new database table.

Question 7

What does the DDL query/update command ALTER TABLE do?

Answer 7

Alters (changes) a database table.

Question 8

What does the DDL query/update command DROP TABLE do?

Answer 8

Deletes a database table.

Question 9

What does the DDL query/update command CREATE INDEX do?

Answer 9

Creates and index (search key).

Question 10

What does the DDL query/update command DROP INDEX do?

Answer 10

Deletes an index.

Question 11

What does DDL stand for?

Answer 11

Data Definition Language

Question 12

What does SQL stand for?

Answer 12

Structured Query Language

Question 13

What is the syntax for using a select statement?

Answer 13

SELECT column_name(s)
FROM table_name

Question 14

How do you select multiple columns using the SELECT statement?

Answer 14

Separate the column names with commas. Ex:

SELECT column_name1, column_name2
FROM table_name

Question 15

What is the syntax used to select all columns from a table?

Answer 15

SELECT * FROM table_name

Question 16

A semicolon is the standard way to separate each SQL statement in database systems that allow more than one SQL statement to be executed in the same call to the server. Is it necessary to use a semicolon?

Answer 16

Not always. It depends on the database program you are using.

Question 17

The result from a SQL query is stored in a ______-___. Most database software systems use programming functions, like: Move-To-First-Record, Get-Record-Content, Move-To-Next-Record, etc. to navigate this with.

Answer 17

result-set

Question 18

The DISTINCT keyword is used to return only distinct (different) values. What is the syntax of a SELECT statement with this keyword added to it?

Answer 18

SELECT DISTINCT column_name(s)

FROM table_name

Question 19

What is the syntax for using a WHERE clause in a SELECT statement?

Answer 19

SELECT column_name FROM table

WHERE column_name value

Question 20

True or False: SQL uses single quotes around text values (most database systems will also accept double quotes). Numeric values however should also be enclosed in quotes.

Answer 20

False, numeric values should not be enclosed in quotes.

Question 21

The LIKE condition is used to specify a search for a pattern in a column. What is the syntax of using LIKE in a SELECT statement?

Answer 21

SELECT column_name FROM table

WHERE column_name LIKE pattern_type

Question 22

A “%” sign can be used to define wildcards (missing letters in the pattern) both before and after the pattern in a LIKE condition. What would the syntax be for a statement that will return all people with first names that start with an ‘O’ in the table Persons? Assume the table has the following columns: FirstName, LastName and Address

Answer 22

SELECT * FROM Persons

WHERE FirstName LIKE ‘O%’

Question 23

A “%” sign can be used to define wildcards (missing letters in the pattern) both before and after the pattern in a LIKE condition. What would the syntax be for a statement that will return all people with first names that contain the letters ‘la’ in them from the table Persons? Assume the table has the following columns: FirstName, LastName and Address

Answer 23

SELECT * FROM Persons

WHERE FirstName LIKE ‘%la%’

Question 24

The INSERT INTO statement is used to insert new rows into a table. What is the syntax for using this command?

Answer 24

INSERT INTO table_name

VALUES (value1, value2,….)

Question 25

Using INSERT INTO, it is possible to specify which column to insert new data into. What is the syntax for this?

Answer 25

INSERT INTO table_name (column_name1, column_name2,…)

VALUES (value1, value2,….)

Question 26

The UPDATE statement is used to modify the data in a table. What is the syntax for this?

Answer 26

UPDATE table_name
SET column_name = new_value
WHERE column_name = some_value

Question 27

The DELETE statement is used to delete rows in a table. What is the syntax for this?

Answer 27

DELETE FROM table_name

WHERE column_name = some_value