Multiple LEFT JOINs in one query in SQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all columns from table1 and left join table2 on id.

SQL

SELECT * FROM table1 LEFT JOIN table2 ON table1.id = table2.[1];

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

Aname

Bvalue

Cdate

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using a column that does not exist in table2.

Joining on columns with different meanings.

The join condition must match the id columns from both tables to link related rows.

2fill in blank

medium

Complete the code to add a second LEFT JOIN to table3 on user_id.

SQL

SELECT * FROM table1 LEFT JOIN table2 ON table1.id = table2.id LEFT JOIN table3 ON table1.[1] = table3.user_id;

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

Aid

Bname

Cuser_id

Ddate

Attempts:

3 left

💡 Hint

Common Mistakes

Joining on columns with different data types.

Using a column that does not exist in table1.

The join uses table1.user_id to match table3.user_id, linking user data correctly.

3fill in blank

hard

Fix the error in the join condition to correctly join table4 on order_id.

SQL

SELECT * FROM table1 LEFT JOIN table4 ON table1.order_id = table4.[1];

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

Aorder_id

Borderid

Cid

Duser_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using a similar but incorrect column name like 'orderid'.

Joining on unrelated columns.

The column names must match exactly; 'order_id' is the correct column in table4.

4fill in blank

hard

Fill both blanks to join table2 and table3 correctly on their respective keys.

SQL

SELECT * FROM table1 LEFT JOIN table2 ON table1.[1] = table2.[2] LEFT JOIN table3 ON table1.user_id = table3.user_id;

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

Aid

Buser_id

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up user_id and id columns.

Using columns that don't exist in the tables.

table1.id matches table2.id for the first join; the second join uses user_id directly.

5fill in blank

hard

Fill all three blanks to join table1, table2, and table3 with correct keys and aliases.

SQL

SELECT t1.*, t2.info, t3.details FROM table1 AS t1 LEFT JOIN table2 AS t2 ON t1.[1] = t2.[2] LEFT JOIN table3 AS t3 ON t1.[3] = t3.user_id;

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

Aid

Cuser_id

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'name' instead of 'id' or 'user_id' for joins.

Mixing up aliases and table names.

t1.id joins with t2.id and t1.user_id joins with t3.user_id for correct data linking.