SELECT with PostgreSQL-specific features - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all columns from the table named 'employees'.

PostgreSQL

SELECT [1] FROM employees;

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A*

BALL

Ccolumns

Deverything

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ALL' instead of '*'

Writing 'columns' or 'everything' which are not valid SQL keywords

Using * selects all columns from the table.

2fill in blank

medium

Complete the code to select the first 5 rows from the 'products' table using PostgreSQL syntax.

PostgreSQL

SELECT * FROM products [1] 5;

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ATOP

BLIMIT

CFETCH

DROWS

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'TOP' which is not valid in PostgreSQL

Using 'FETCH' or 'ROWS' without the full syntax

PostgreSQL uses LIMIT to restrict the number of rows returned.

3fill in blank

hard

Fix the error in the query to select distinct city names from the 'customers' table.

PostgreSQL

SELECT DISTINCT [1] FROM customers;

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Acity_name

Bcities

Ccity

Dcustomer_city

Attempts:

3 left

💡 Hint

Common Mistakes

Using plural or incorrect column names

Using column names that do not exist in the table

The column name is city. Using the correct column name avoids errors.

4fill in blank

hard

Fill both blanks to select the name and the length of the name from the 'users' table using PostgreSQL functions.

PostgreSQL

SELECT name, [1](name) AS name_length FROM users WHERE [2](name) > 5;

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ALENGTH

BLEN

CSIZE

DCOUNT

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'LEN' which is not valid in PostgreSQL

Using 'SIZE' or 'COUNT' which do not measure string length

PostgreSQL uses the LENGTH function to get the number of characters in a string.

5fill in blank

hard

Fill all three blanks to select the name in uppercase, the length of the name, and filter names longer than 3 characters from the 'members' table.

PostgreSQL

SELECT [1](name) AS upper_name, [2](name) AS name_len FROM members WHERE [3](name) > 3;

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AUPPER

BLENGTH

DLOWER

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'LOWER' instead of 'UPPER' for uppercase conversion

Using 'LEN' instead of 'LENGTH' for string length

UPPER converts text to uppercase, and LENGTH returns the number of characters in the string.