SQL

What does a relational database define?

Relationships within tables of data inside the database.

How does a relational database differ from a spreadsheet?

It is more powerful, secure, and allows more people to access data simultaneously.

What is SQL?

Structured Query Language, the most widely used programming language for databases.

What are the two main components of a database table?

Rows (records) and Columns (fields).

What must be true about field names in a database?

Field names must be lowercase, singular, contain no spaces, and cannot have the same name as another field.

What is the purpose of a unique identifier in a database?

To distinguish records from one another within the same table.

What is a string in the context of data types?

A sequence of characters such as letters or punctuation.

What does VARCHAR represent?

A flexible and popular string data type that can store very long strings.

What is the function of a schema in a database?

It serves as a blueprint of the database, outlining what tables are included and their relationships.

What is a server in relation to a database?

A centralised computer that performs services over a network, including data access.

What type of SQL query would you use to select all fields from a table?

SELECT * FROM table_name;.

How do you select distinct records?

Using the query SELECT DISTINCT column_name FROM table_name;.

What is a view in SQL?

A virtual table that is the result of a SELECT statement, automatically updating in response to database changes.

What distinguishes PostgreSQL from SQL Server?

They are both relational database systems but have different keywords and features.

What do the keywords SELECT and FROM do in an SQL query?

SELECT indicates the fields to be selected, while FROM indicates the table that those fields are located in.

What is the purpose of aliasing in SQL?

To rename columns in a query for clarity or brevity without changing the actual table.

What is the significance of the LIMIT clause in an SQL query?

It limits the number of results returned, useful for testing code.