SQL KEY CONCEPTS

Question 1

What is a table in a database?

Answer 1

a collection of related data in a database.
- it is made up of rows & columns
Example - A “Customers” table might have columns for customer names, IDs, & contact information.

Question 2

What is a column in a database?

Answer 2

Is a field in a table that stores specific types of data, such as names or dates.
EXAMPLE - In a “Products” table, there might be a column for “Price” & another for “Description.”

Question 3

What is a row in a database?

Answer 3

• is a record in a table, containing related data fields for one entry.
  *Example** - In a “Customers” table, one row could store the name, ID, & contact information of one customer.

Question 4

What is a primary key?

Answer 4

• Is a unique identifer for each record in a table.
• No two rows can have the same primary key.
  Example - A customer ID number might be a primary key in a “Customers” table.

Question 5

What is a foreign key?

Answer 5

• is a field in one table that links to the primary key in another table.
• It is used to create relationships between tables.
  Examples - In an “Orders” table, a foreign key might link to the “Customers” table using the customer ID.

Question 6

What are the main SQL commands?

Answer 6

1. SELECT: Retrieves data from a database
2. INSERT: Adds new data to a table
3. UPDATE: Modifies existing data.
4. DELETE: Removes data from a table.
5. CREATE: Creates new tables or databases.
6. DROP: Deletes tables or database.

Question 7

SELECT
- What is the purpose of SQL commands SELECT?

Answer 7

Retrieves data from a database

Question 8

INSERT
- What is the purpose of SQL commands INSERT?

Answer 8

Adds new data to a table

Question 9

UPDATE
- What is the purpose of SQL commands UPDATE?

Answer 9

Modifies existing data.

Question 9

DELETE
- What is the purpose of SQL commands DELETE?

Answer 9

Removes data from a table.

Question 10

CREATE
- What is the purpose of SQL commands CREATE?

Answer 10

Creates new tables or databases.

Question 11

DROP
- What is the purpose of SQL commands DROP?

Answer 11

Deletes tables or database.

Question 12

Example of table in a database

Answer 12

Example - A “Customers” table might have columns for customer names, IDs, & contact information.

Question 13

Example of column in a database

Answer 13

EXAMPLE - In a “Products” table, there might be a column for “Price” & another for “Description.”

Question 14

Example of row in a database

Answer 14

*Example** - In a “Customers” table, one row could store the name, ID, & contact information of one customer.

Question 15

Example of primary key in a database

Answer 15

Example - A customer ID number might be a primary key in a “Customers” table.

Question 16

Example of foreign key in a database

Answer 16

Examples - In an “Orders” table, a foreign key might link to the “Customers” table using the customer ID.

Question 17

What is a table in a database? (In More Detail)
- Define:
- Example:

Answer 17

1. Define: A table is a collection of related data in a database. It is made up of rows and columns.
2. Example: A “Customers” table might have columns for customer names, IDs, and contact information.

Question 18

What is a column in a database? (In More Detail)
- Define:
- Example:

Answer 18

1. Define: A column is a field in a table that stores specific types of data, such as names or dates.
2. Example: In a “Products” table, there might be a column for “Price” and another for “Description.”

Question 19

What is a row in a database? (In more Detail)
- Define:
- Example:

Answer 19

1. Define: A row is a record in a table, containing related data fields for one entry.
2. Example: In a “Customers” table, one row could store the name, ID, and contact information of one customer.

Question 20

What is a primary key? (In more Detail)
- Define:
- Example:

Answer 20

1. Define: A primary key is a unique identifier for each record in a table. No two rows can have the same primary key.
2. Example: A customer ID number might be a primary key in a “Customers” table.

Question 21

What is a foreign key? (In more Detail)
- Define:
- Example:

Answer 21

1. Define: A foreign key is a field in one table that links to the primary key in another table. It is used to create relationships between tables.
2. Example: In an “Orders” table, a foreign key might link to the “Customers” table using the customer ID.