Table Components

Question 1

What are some characteristics of a table?

Answer 1

It must contain at least one column, but it can contain zero rows.

Each column has to have a defined data type.

Columns can be set to allow or prevent null values.

Question 2

What is a primary Key?

Answer 2

The Primary Key is a column or set of columns that makes a record unique in a table.

Question 3

What is a Foreign Key?

Answer 3

A Foreign Key references the primary key in another table

Question 4

Can a table have multiple Foreign Keys?

Answer 4

Yes!

Question 5

Do the values need to be unique in a foreign key?

Answer 5

no

Question 6

Do the values need to be unique in a primary key?

Answer 6

Yes

Question 7

What is an Identity Column?

Answer 7

A numeric column that automatically increments when a new record is added to a table.

Question 8

What is a NULL value?

Answer 8

An undefined value (not a blank value). Like a question that hasn’t been answered.

Question 9

What is an exact numeric?

Answer 9

Its a data type like a bit, int, decimal, numeric, or money that stores numbers of various precision

Question 10

What is a bit?

Answer 10

Can only can values like 1 or 0

Question 11

What is an int?

Answer 11

Can only contain whole numbers (can be negative)

Question 12

what is a decimal (p,s)

Answer 12

Can contain whole or decimal numbers. The p parameter specifies the total number of digits that the number can hold, and the s parameter specifies the number of digits to the right of the decimal point (scale).

Question 13

How many decimal places can the decimal (p,s) go?

Answer 13

38

Question 14

How many decimal places can the money numeric go?

Answer 14

4 decimal places

Question 15

What is an approximate numeric?

Answer 15

Float and Real are approximate numerics. They are used when the precision of a number may exceed 38 places. They may not return an exact value.

Question 16

What is the difference between float and real?

Answer 16

Real has a smaller range than float.

Question 17

What is datetime2

Answer 17

Stores precise date and time

Question 18

What is char (n)?

Answer 18

Stores fixed length character data like zip codes. Includes trailing spaces

Question 19

What is varchar (n)

Answer 19

It stores character data as variable lengths.

Question 20

What is varchar(max)

Answer 20

It stores large amounts of variable character data. Good for something like an essay.

Question 21

What is nchar(n)?

Answer 21

It stores fixed length foreign character data. Like chinese characters.

Question 22

What is nvarchar(n)?

Answer 22

It stores variable foreign character data lengths.

Question 23

What is nvarchar(max)?

Answer 23

It stores large amounts of variable character data.

Question 24

What is binary(n)?

Answer 24

Stores encrypted fixed-width data up to 8,000 bytes. The ‘n’ tells you how long. If the data is shorter than (n) length then it will be padded with zeros.

Question 25

What is the ‘n’ in varchar(n)?

Answer 25

The maximum number of bytes that can be stored.

Question 26

What is ‘max’ in varchar(max)?

Answer 26

It indicates that the column can store up to 2GB of data

Question 27

what is varbinary(n)?

Answer 27

Its for binary data used to store encrypted information like passwords that may vary in length. It stores up to 4,000 bytes.

Question 28

What is a byte?

Answer 28

Bytes are used to encode and store data in computer memory and storage devices. A byte consists of 8 bits. A bit is the smallest unit of data in a computer, representing a binary value of either 0 or 1.

Question 29

What is varbinary(max)?

Answer 29

Its for binary data used to store encrypted information. It stores character data up to 2GB.

Question 30

What are some alphanumeric data types?

Answer 30

char(n), varchar(n), varchar(max), text

Question 31

What is implicit conversion?

Answer 31

When SQL servers can convert the datatype automatically.

Question 32

What is explicit conversion?

Answer 32

When a CAST or CONVERT function must be used to convert the datatype.