Lesson 5: Designing SQL Data Tables

Question 1

CREATE TABLE

Answer 1

CREATE TABLE is a SQL statement that is used to create a new table in a database.

Question 2

ALTER TABLE

Answer 2

ALTER TABLE is the SQL statement that is used to alter or change the structure of an existing database table. This statement can be used to add constraints

Question 3

Constraint

Answer 3

A SQL constraint is a rule for data in the database.

Question 4

PRIMARY KEY (PK)

Answer 4

A PRIMARY KEY is a SQL constraint. It is the column that uniquely identifies each row in the table. A PK cannot be NULL, and there can only be one PK in each table.

Question 5

FOREIGN KEY (FK)

Answer 5

A FOREIGN KEY is a key used to relate or link two tables together. The PK is a column in one table that refers to the FK in another table.

Question 6

Data Types

Answer 6

The data type of a column defines what value the column can store

Question 7

nvarchar

Answer 7

A data type that can hold string data. Also, a variable width that also holds unicode data or multilingual data
“Unicode Character Strings data type that can store variable-size string data. Unicode data types can store character data and so work well if there are international words or data that will be stored.”

Question 8

int

Answer 8

A data type that holds whole numbers. There are different int data types each determines how big the whole number can be

Question 9

decimal (p, s)

Answer 9

A data type that holds numbers with decimals. The default size is 18 numbers (precision) and 0 decimals (scale). You will define how many digits (the precision) the decimal can have and how many decimal places (the scale) it can have. Default is 18 digits with no decimal places

Question 10

date

Answer 10

A data type that stores dates only Format YYYY-MM-DD

Question 11

NULL

Answer 11

A constraint that indicates the data can hold null values or that the column can be empty of data.

Question 12

NOT NULL

Answer 12

NOT NULL is a constraint rule that ensures there is always data entered in a column. A new row cannot be added without data in the column that is defined as NOT NULL

Question 13

DROP TABLE

Answer 13

DROP TABLE is a SQL statement to remove a table and all its data rows from the database “DROP TABLE is a SQL statement that needs to be carefully considered before executing it in a live database. The table and all its data will be lost if the DROP TABLE SQL statement is executed.”

Question 14

Debugging

Answer 14

Making corrections to remove bugs or errors in the code.