sql-select

Question 1

What is SQL and how is it different from languages like JavaScript?

Answer 1

SQL (Structured Query Language) is the primary way of interacting with relational databases. It can be used to retrieve, create, and manipulate data in a relational database. SQL is different from languages like JavaScript in that it is a declarative programming language. Programmers describe the results they want and the programming environment comes up with its own plan for getting those results.

Question 2

How do you retrieve specific columns from a database table?

Answer 2

Use the ‘select’ keyword followed by the name of the column

Question 3

How do you filter rows based on some specific criteria?

Answer 3

Use the ‘where’ clause followed by a category name and a comparison (string in single quotes; numbers/booleans no quotes)

Question 4

What are the benefits of formatting your SQL?

Answer 4

Formatting makes it easier to read and debug

Question 5

What are four comparison operators that can be used in a where clause?

Answer 5

=, <, >, !=

Question 6

How do you limit the number of rows returned in a result set?

Answer 6

Use the ‘limit’ clause followed by the integer number (with no quotes) you want to limit it to

Question 7

How do you retrieve all columns from a database table?

Answer 7

select *

Question 8

How do you control the sort order of a result set?

Answer 8

Use the ‘order by’ clause followed by a column name (in double quotes), can also add ‘desc’ (default is ascending)