What is PostgreSQL - Interactive Quiz & Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all columns from a table named users.

PostgreSQL

SELECT [1] FROM users;

Drag options to blanks, or click blank then click option'

A*

BALL

CCOLUMNS

DEVERYTHING

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ALL' instead of '*' causes syntax error.

Writing 'COLUMNS' or 'EVERYTHING' is not valid SQL.

The asterisk (*) means select all columns from the table.

2fill in blank

medium

Complete the code to create a new table named products with an id column.

PostgreSQL

CREATE TABLE [1] (id SERIAL PRIMARY KEY);

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Aorders

Bproducts

Citems

Dcustomers

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong table names like 'items' or 'orders'.

Misspelling the table name.

The table name should be 'products' as requested.

3fill in blank

hard

Fix the error in the query to get the count of rows in the users table.

PostgreSQL

SELECT COUNT([1]) FROM users;

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Auser_id

Bid

Call

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using a column name that may have nulls, causing wrong counts.

Using 'all' which is not valid syntax.

Using COUNT(*) counts all rows regardless of column values.

4fill in blank

hard

Fill all three blanks to select name and age from people where age is greater than 30.

PostgreSQL

SELECT [1], [2] FROM people WHERE age [3] 30;

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Aname

Bage

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in the WHERE clause.

Selecting wrong columns or missing commas.

Select 'name' and 'age' columns and filter rows where age is greater than 30.

5fill in blank

hard

Fill all three blanks to insert a new user with name 'Alice' and age 25 into the users table.

PostgreSQL

INSERT INTO users ([1], [2]) VALUES ([3], 25);

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Aname

B'Alice'

Cage

D'25'

Attempts:

3 left

💡 Hint

Common Mistakes

Putting numeric values in quotes.

Mixing up column names and values.

Insert into columns 'name' and 'age' the values 'Alice' and 25 respectively.