Variables and control flow in dbt - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of variable assignment and if condition in dbt

What is the output of the following dbt Jinja code snippet when run inside a model?

dbt

{% set x = 5 %}
{% if x > 3 %}
  {{ x * 2 }}
{% else %}
  {{ x + 2 }}
{% endif %}

A 10

B 7

C 5

D Error: Undefined variable

💡 Hint

Check the value of x and the condition in the if statement.

The variable x is set to 5. Since 5 is greater than 3, the if block runs, outputting 5 * 2 = 10.

❓ data_output

intermediate

Result of loop with variable increment in dbt

What list will be output by this dbt Jinja code?

dbt

{% set result = [] %}
{% set counter = 0 %}
{% for i in range(3) %}
  {% set counter = counter + i %}
  {% do result.append(counter) %}
{% endfor %}
{{ result }}

A [0, 1, 3]

B [0, 0, 0]

C [1, 3, 6]

D Error: 'do' statement not allowed

💡 Hint

Remember that counter starts at 0 and increments by i each loop.

Loop runs with i=0,1,2. counter updates: 0+0=0, 0+1=1, 1+2=3. Result list collects these values.

🔧 Debug

advanced

Identify the error in variable scope within dbt Jinja

Why does the following dbt code raise an error or produce unexpected output?

dbt

{% for i in range(2) %}
  {% set val = i * 2 %}
{% endfor %}
{{ val }}

A val holds the last value from the loop, outputting 2

B val is undefined outside the loop, causing an error

C val is a list of all values from the loop, outputting [0, 2]

D SyntaxError due to missing endfor

💡 Hint

Consider variable scope inside and outside loops in Jinja.

In dbt Jinja, variables set inside loops are local to the loop block and not accessible outside, so val is undefined after the loop.

🧠 Conceptual

advanced

Understanding control flow with nested if-else in dbt

Given the variable 'score' set to 75, what will this dbt Jinja code output?

dbt

{% set score = 75 %}
{% if score >= 90 %}
  Excellent
{% elif score >= 70 %}
  Good
{% else %}
  Needs Improvement
{% endif %}

A Excellent

B Error: Invalid syntax

C Needs Improvement

D Good

💡 Hint

Check the conditions in order and which one matches 75.

75 is not >= 90 but is >= 70, so the elif block runs, outputting 'Good'.

🚀 Application

expert

Predict the output of complex variable manipulation and control flow in dbt

What is the final output of this dbt Jinja code snippet?

dbt

{% set data = [1, 2, 3, 4] %}
{% set total = 0 %}
{% for num in data %}
  {% if num % 2 == 0 %}
    {% set total = total + num * 2 %}
  {% else %}
    {% set total = total + num %}
  {% endif %}
{% endfor %}
{{ total }}

A 15

B 20

C 18

D Error: Cannot modify variable inside loop

💡 Hint

Calculate total step by step, doubling even numbers before adding.

Loop over [1,2,3,4]: 1 (odd) add 1 → total=1 2 (even) add 4 → total=5 3 (odd) add 3 → total=8 4 (even) add 8 → total=16 Final total is 16.