PostgreSQL vs MySQL key differences - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

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

PostgreSQL

SELECT [1] FROM employees;

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Aeverything

B*

CALL

Dcolumns

Attempts:

3 left

💡 Hint

Common Mistakes

Using words like ALL or columns instead of *

Leaving the blank empty

In SQL, * means select all columns from the table.

2fill in blank

medium

Complete the code to limit the number of rows returned to 5 in PostgreSQL.

PostgreSQL

SELECT * FROM products [1] 5;

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ALIMIT

BFETCH

CTOP

DROWNUM

Attempts:

3 left

💡 Hint

Common Mistakes

Using TOP which is for SQL Server or MySQL

Using ROWNUM which is for Oracle

PostgreSQL uses LIMIT to restrict the number of rows returned.

3fill in blank

hard

Fix the error in the PostgreSQL query to add a new column named 'age' of type integer.

PostgreSQL

ALTER TABLE users [1] COLUMN age INTEGER;

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AADD

BCHANGE

CMODIFY

DUPDATE

Attempts:

3 left

💡 Hint

Common Mistakes

Using MODIFY or CHANGE which are MySQL keywords

Using UPDATE which is for changing data, not structure

In PostgreSQL, to add a new column, use ADD COLUMN.

4fill in blank

hard

Fill both blanks to write a PostgreSQL query that selects all columns from 'orders' and orders results by 'order_date' descending.

PostgreSQL

SELECT [1] FROM orders ORDER BY order_date [2];

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A*

BASC

CDESC

DALL

Attempts:

3 left

💡 Hint

Common Mistakes

Using ASC instead of DESC for descending order

Using ALL instead of * for selecting columns

Use * to select all columns and DESC to sort descending.

5fill in blank

hard

Fill all three blanks to write a PostgreSQL query that creates a table 'customers' with columns 'id' as serial primary key, 'name' as text, and 'email' as unique text.

PostgreSQL

CREATE TABLE customers (id [1] PRIMARY KEY, name [2], email [3] UNIQUE);

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ASERIAL

BTEXT

DVARCHAR

Attempts:

3 left

💡 Hint

Common Mistakes

Using VARCHAR instead of TEXT for name or email

Not using SERIAL for id column

Use SERIAL for auto-increment id, and TEXT for name and email columns.