Running total without window functions in SQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all sales amounts from the sales table.

SQL

SELECT [1] FROM sales;

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

Aprice

Btotal

Camount

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting a column name that does not exist in the table.

Using a keyword instead of a column name.

The column that stores the sales amount is named amount. Selecting this column will show all sales amounts.

2fill in blank

medium

Complete the code to calculate the running total of sales amounts using a correlated subquery.

SQL

SELECT s1.id, s1.amount, (SELECT SUM(s2.amount) FROM sales s2 WHERE s2.id <= [1]) AS running_total FROM sales s1 ORDER BY s1.id;

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

As1.id

Bs2.id

Cs2.amount

Ds1.amount

Attempts:

3 left

💡 Hint

Common Mistakes

Using the inner query alias s2.id instead of the outer s1.id.

Comparing the wrong columns in the WHERE clause.

The correlated subquery compares s2.id to s1.id to sum all amounts up to the current row. So, s1.id is the correct reference.

3fill in blank

hard

Fix the error in the code to correctly calculate the running total without window functions.

SQL

SELECT id, amount, (SELECT SUM(amount) FROM sales WHERE id [1] id) AS running_total FROM sales ORDER BY id;

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

A>

B>=

C=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using = which sums only the current row.

Using > which sums rows after the current one.

To get the running total up to the current row, we sum amounts where id <= current id. Using <= includes the current row.

4fill in blank

hard

Fill both blanks to create a running total query that sums amounts up to the current row id.

SQL

SELECT s1.id, s1.amount, (SELECT SUM([1]) FROM sales s2 WHERE s2.id [2] s1.id) AS running_total FROM sales s1 ORDER BY s1.id;

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

Aamount

B<=

C>=

Dtotal

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong column name in the sum.

Using the wrong comparison operator.

The subquery sums the amount column where s2.id <= s1.id to include all rows up to the current one.

5fill in blank

hard

Fill all three blanks to write a running total query without window functions, using aliases and correct comparison.

SQL

SELECT [1], [2], (SELECT SUM([3]) FROM sales s2 WHERE s2.id <= s1.id) AS running_total FROM sales s1 ORDER BY s1.id;

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

As1.id

Bs1.amount

Camount

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using columns without the correct alias.

Using the wrong column name in the sum.

The outer query selects s1.id and s1.amount. The subquery sums the amount column from s2 where s2.id <= s1.id to get the running total.