SQL

Question 1

What is a primary key?

Answer 1

Unique identifier in each row of the table

Question 2

What is an entity?

Answer 2

Any person or thing in the database

Question 3

What is a foreign key?

Answer 3

A foreign key is a field which is a primary key in a linked table

Question 4

What is data redundancy?

Answer 4

Waste of data

Question 5

What is data inconsistency ?

Answer 5

When the same data exists in different formats in multiple tables

Question 6

What is Structured Query Language (SQL) ?

Answer 6

A language used for enquiring and updating database tables in a relational database.

Question 7

SELECT…FROM…WHERE meaning

Answer 7

SELECT list of fields to be displayed
FROM list the table or tables where the data will come from
WHERE list of search criteria
ORDER BY list the fields that the results are to be sorted on (default is Ascending)

Question 8

What are the 4 types of SQL?

Answer 8

Search, Update, Insert and Delete

Question 9

How does an Insert SQL work?

Answer 9

INSERT INTO tableName(column1, column 2)
VALUES (value1, value2)

Question 10

How does an Update SQL work?

Answer 10

UPDATE tableName
SET column1 = value1, column2 = value2
WHERE column = value

Question 11

How does delete SQL work?

Answer 11

DELETE FROM tableName
WHERE column = value

Question 12

Which SQL statement is used to return only different values?

Answer 12

SELECT DISTINCT

Question 13

With SQL, how can you insert “Olsen” as the “LastName” in the “Persons” table?

Answer 13

INSERT INTO Persons (LastName) VALUES (‘Olsen’)

Question 14

Which operator is used to select values within a range?

Answer 14

BETWEEN

Question 15

Which operator is used to search for a specified pattern in a column?

Answer 15

LIKE