Quiz

1. What is a SQL query used for?

A. To ask the database for help

Incorrect. A database generally does not offer help functionality like what is found in desktop operating systems.

B. To retrieve records from a database

Correct! Queries are used to extract data stored within a database.

C. To add data to a database

Incorrect. While a query is used when interacting with a database, it is not used to add data to it.

D. To change data within a database

Incorrect. While a query is used when interacting with a database, it is not used to change data within it.

2. What is needed for the most basic SQL query?

A. A SELECT statement, a WHERE clause, and a table name

Incorrect. WHERE clauses are optional, and this query would be missing several key pieces.

B. A QUERY statement, at least one column name, a FROM clause, and a table name

Incorrect. While a query must contain a column, FROM clause, and table name, there is no QUERY statement in SQL.

C. A SELECT statement, a wildcard, an IN clause, and a table name

Incorrect. While a simple query could have a wildcard in it, the SQL IN clause is not what is used to refer to a particular table.

D. A SELECT statement, at least one column name, a FROM clause, and a table name

Correct! These are the four most basic elements of an SQL query.

3. Which of the following is NOT a proper SQL query?

A. SELECT * FROM customer

Incorrect. This query contains the necessary SELECT statement, a "*" wildcard for all columns, the FROM clause, and a table name.

B. SELECT name FROM personnel

Incorrect. This query contains the necessary SELECT statement, a column name, the FROM clause, and a table name.

C. SELECT ALL FIELDS FROM tenants

Correct! If one wishes to select all fields in a table, the proper way to do it is by using the "*" wildcard.

D. SELECT * FROM receipts WHERE day="Wednesday"

Incorrect. This query contains the necessary SELECT statement, a column name, the FROM clause, and a table name, and an additional WHERE clause with a specified column and value.

4. Which of the following queries would retrieve all records in the "guests" table with the hometown "Chicago"?

A. SELECT * FROM guests IF hometown="Chicago"

Incorrect. There is no IF clause in SQL.

B. SELECT * FROM guests WHERE hometown="Chicago"

Correct! This query would return all records which had the value "Chicago" in the hometown field.

C. SELECT guests WHERE hometown="Chicago"

Incorrect. This query is missing column names (or a wildcard in place of them).

D. SELECT * WHERE hometown="Chicago" FROM guests

Incorrect. While this query has all the right pieces, the clauses are in the wrong order.

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Basic SQL Queries

By Justin Callanan

Quiz