How dbt works (SQL + Jinja + YAML) - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all columns from the source table in a dbt model.

dbt

select * from [1]

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

Asource('my_source', 'my_table')

Bref('my_source')

Cconfig('my_source')

Drun_query('my_source')

Attempts:

3 left

💡 Hint

Common Mistakes

Using ref() instead of source() for raw tables.

Trying to call config() or run_query() which are not for table references.

In dbt, source() is used to refer to raw tables defined in YAML source configurations.

2fill in blank

medium

Complete the YAML snippet to define a source named 'raw_data' with a table 'users'.

dbt

sources:
  - name: [1]
    tables:
      - name: users

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

Astaging

Bmodels

Craw_data

Danalytics

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'models' or 'staging' which are not source names.

Confusing source name with table name.

The name under sources defines the source name, here it should be 'raw_data'.

3fill in blank

hard

Fix the error in the Jinja code to correctly reference a model named 'orders'.

dbt

select * from [1]

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

Asource('orders')

Bref('orders')

Cconfig('orders')

Drun_query('orders')

Attempts:

3 left

💡 Hint

Common Mistakes

Using source() to reference models instead of raw tables.

Using config() or run_query() which are not for referencing tables.

To reference another dbt model, use ref('model_name'). source() is for raw tables.

4fill in blank

hard

Fill both blanks to create a dbt model that selects user_id and counts orders, grouping by user_id.

dbt

select user_id, count(*) as order_count from [1] group by [2]

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

Aref('orders')

Buser_id

Corder_id

Dsource('raw_data', 'orders')

Attempts:

3 left

💡 Hint

Common Mistakes

Using source() instead of ref() for models.

Grouping by wrong column like order_id.

The table is referenced by ref('orders') and grouping is done by user_id.

5fill in blank

hard

Fill all three blanks to create a YAML test that checks if the 'email' column in 'users' model is unique and not null.

dbt

models:
  - name: users
    columns:
      - name: email
        tests:
          - [1]
          - [2]:
              severity: [3]

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

Aunique

Bnot_null

Cwarn

Derror

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up test names or severity levels.

Using 'warn' when 'error' is expected for strict checks.

The tests unique and not_null check column constraints. Severity error marks failures as errors.

Practice

1. What is the main role of Jinja in dbt projects?

easy

A. To add logic and dynamic behavior to SQL queries

B. To write raw SQL queries without any modification

C. To manage configuration and documentation files

D. To execute the SQL queries on the database

Solution

1. Step 1: Understand Jinja's purpose in dbt

   Jinja is a templating language that allows adding logic like loops and conditions inside SQL files.

2. Step 2: Differentiate roles of SQL, Jinja, and YAML

   SQL writes queries, YAML manages configs/docs, and Jinja adds dynamic logic to SQL.

3. Final Answer:

   To add logic and dynamic behavior to SQL queries -> Option A

4. Quick Check:

   Jinja = logic in SQL [OK]

Hint: Jinja = logic inside SQL, YAML = configs/docs [OK]

Common Mistakes:

• Confusing Jinja with YAML for configs
• Thinking Jinja executes SQL queries
• Assuming Jinja writes raw SQL without changes

2. Which of the following is the correct way to use a Jinja variable inside a dbt SQL model?

easy

A. SELECT * FROM var('table_name')

B. SELECT * FROM {{ var('table_name') }}

C. SELECT * FROM {% var('table_name') %}

D. SELECT * FROM [[ var('table_name') ]]

Solution

1. Step 1: Recall Jinja syntax for variables

   Jinja variables are inserted using double curly braces {{ }} around expressions.

2. Step 2: Identify correct syntax for var function

   The correct syntax is {{ var('variable_name') }} to access a variable in dbt.

3. Final Answer:

   SELECT * FROM {{ var('table_name') }} -> Option B

4. Quick Check:

   Jinja variables use {{ }} [OK]

Hint: Use {{ var('name') }} to insert variables in SQL [OK]

Common Mistakes:

• Using single curly braces or wrong brackets
• Confusing Jinja tags {% %} with variable insertion {{ }}
• Using square brackets instead of curly braces

3. Given this dbt model SQL code, what will be the output SQL after rendering?

SELECT
  user_id,
  {% if var('include_email', false) %}
    email,
  {% endif %}
  created_at
FROM users

Assuming the variable include_email is set to true in dbt_project.yml.

medium

A. SELECT user_id, true, created_at FROM users

B. SELECT user_id, created_at FROM users

C. Syntax error due to misplaced Jinja

D. SELECT user_id, email, created_at FROM users

Solution

1. Step 1: Check the value of the variable include_email

   The variable include_email is true, so the if condition passes and the email column is included.

2. Step 2: Render the SQL with the if block included

   The SQL will have user_id, email, and created_at columns selected from users.

3. Final Answer:

   SELECT user_id, email, created_at FROM users -> Option D

4. Quick Check:

   include_email true means email included [OK]

Hint: If var true, include block inside {% if %} [OK]

Common Mistakes:

• Ignoring the variable value and excluding email
• Thinking Jinja syntax causes SQL errors
• Confusing variable default values

4. You wrote this YAML config in your dbt project:

models:
  my_project:
    +materialized: table
      users:
        +tags: ['important']

Why does dbt raise an error when running?

medium

A. Because the indentation for 'users' is incorrect under 'my_project'

B. Because '+materialized' cannot be set in YAML

C. Because tags must be a string, not a list

D. Because 'models' key is missing

Solution

1. Step 1: Check YAML indentation rules for dbt configs

   In dbt, model configs under a project must be indented properly; 'users' should be at the same level as '+materialized'.

2. Step 2: Identify the indentation error

   'users' is indented too far, making it a child of '+materialized' which is invalid.

3. Final Answer:

   Because the indentation for 'users' is incorrect under 'my_project' -> Option A

4. Quick Check:

   YAML indentation matters for nested configs [OK]

Hint: Check YAML indentation carefully for nested configs [OK]

Common Mistakes:

• Ignoring YAML indentation importance
• Thinking '+materialized' is invalid syntax
• Assuming tags cannot be lists

5. You want to create a dbt model that selects only active users from a table, but the 'active' flag is stored in a YAML config. Which approach correctly combines SQL, Jinja, and YAML to achieve this?

hard

A. Use Jinja to read YAML directly inside SQL without defining variables

B. Write WHERE active = true directly in SQL without YAML or Jinja

C. Define 'active_flag: true' in YAML, then use WHERE active = {{ var('active_flag') }} in SQL with Jinja

D. Set 'active_flag' in YAML but forget to use Jinja in SQL, so filter is missing

Solution

1. Step 1: Store the filter value in YAML as a variable

   Define 'active_flag: true' in YAML under vars or config to make it accessible.

2. Step 2: Use Jinja to insert the variable in SQL WHERE clause

   Use WHERE active = {{ var('active_flag') }} so the SQL filters active users dynamically.

3. Final Answer:

   Define 'active_flag: true' in YAML, then use WHERE active = {{ var('active_flag') }} in SQL with Jinja -> Option C

4. Quick Check:

   YAML vars + Jinja in SQL = dynamic filters [OK]

Hint: Use YAML vars + Jinja {{ var() }} in SQL WHERE [OK]

Common Mistakes:

• Hardcoding filter in SQL ignoring YAML
• Not using Jinja to insert YAML vars
• Trying to read YAML directly in SQL without var()