ref() function for model dependencies in dbt - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to reference the model named 'customers' using the ref() function.

dbt

select * from [1]('customers')

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

Asource

Bref

Ctable

Dmodel

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'source()' instead of 'ref()' to reference models.

Trying to use 'table()' or 'model()' which are not valid dbt functions.

The ref() function is used in dbt to reference other models by name, ensuring dependencies are tracked correctly.

2fill in blank

medium

Complete the code to create a model that selects all columns from the 'orders' model using ref().

dbt

select * from [1]('orders')

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

Asource

Btable

Cref

Dload

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'source()' which is for external tables, not models.

Using 'load()' which is not a dbt function.

Using ref('orders') tells dbt to use the 'orders' model as a dependency.

3fill in blank

hard

Fix the error in the code to correctly reference the 'sales' model with ref().

dbt

select * from [1]('sales')

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

Aref('sales')

Bref(sales)

Csource('sales')

Dref

Attempts:

3 left

💡 Hint

Common Mistakes

Putting the whole function call inside the blank.

Using source() instead of ref().

The ref function must be called with parentheses and the model name as a string inside. In this code, the blank should be just ref so that the full call is ref('sales').

4fill in blank

hard

Fill both blanks to create a model that selects the 'id' and 'amount' columns from the 'transactions' model using ref().

dbt

select id, amount from [1]([2])

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

Aref

B'transactions'

C'orders'

Dsource

Attempts:

3 left

💡 Hint

Common Mistakes

Using source instead of ref.

Not putting the model name in quotes.

The ref function is called with the model name as a string. Here, ref('transactions') correctly references the 'transactions' model.

5fill in blank

hard

Fill all three blanks to create a model that selects 'customer_id' and 'total' from the 'invoices' model, using ref(), and filters totals greater than 100.

dbt

select [1], [2] from [3]('invoices') where total > 100

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

Acustomer_id

Btotal

Cref

Dsource

Attempts:

3 left

💡 Hint

Common Mistakes

Using source instead of ref.

Swapping the column names or missing quotes in the function call.

The columns to select are customer_id and total. The model is referenced with ref('invoices').

Practice

1. What is the main purpose of the ref() function in dbt?

easy

A. To create new database users

B. To write raw SQL queries inside dbt models

C. To link models and define dependencies between them

D. To schedule dbt runs automatically

Solution

1. Step 1: Understand the role of ref()

   The ref() function is used to link one model to another in dbt, so dbt knows the order to run models and their dependencies.

2. Step 2: Identify what ref() does not do

   It does not write raw SQL, create users, or schedule runs. Its main role is linking models.

3. Final Answer:

   To link models and define dependencies between them -> Option C

4. Quick Check:

   ref() links models = A [OK]

Hint: Remember: ref() connects models, not SQL or users [OK]

Common Mistakes:

• Thinking ref() writes SQL code
• Confusing ref() with scheduling tools
• Assuming ref() manages database users

2. Which of the following is the correct syntax to reference a model named customers inside another model using ref()?

easy

A. select * from {{ ref('customers') }}

B. select * from ref('customers')

C. select * from ref(customers)

D. select * from {{ ref(customers) }}

Solution

1. Step 1: Recall dbt Jinja syntax for ref()

   In dbt, ref() must be wrapped in double curly braces and the model name must be a string in quotes.

2. Step 2: Check each option

   select * from {{ ref('customers') }} uses {{ ref('customers') }} which is correct. Options B and C miss the curly braces or quotes. select * from {{ ref(customers) }} misses quotes around the model name.

3. Final Answer:

   select * from {{ ref('customers') }} -> Option A

4. Quick Check:

   Use {{ ref('model_name') }} syntax = A [OK]

Hint: Always use {{ ref('model_name') }} with quotes and braces [OK]

Common Mistakes:

• Omitting curly braces {{ }}
• Not putting model name in quotes
• Using ref() without Jinja syntax

3. Given the following dbt model code, what will be the output SQL after compilation if the orders model exists?

select order_id, customer_id
from {{ ref('orders') }}

medium

A. select order_id, customer_id from orders

B. select order_id, customer_id from {{ ref('orders') }}

C. select order_id, customer_id from dbt.orders

D. select order_id, customer_id from ref('orders')

Solution

1. Step 1: Understand what ref() compiles to

   The ref() function compiles to the actual table name of the referenced model, usually just the model name like 'orders'.

2. Step 2: Check the compiled SQL output

   The compiled SQL replaces {{ ref('orders') }} with orders, so the output is select order_id, customer_id from orders.

3. Final Answer:

   select order_id, customer_id from orders -> Option A

4. Quick Check:

   ref('orders') compiles to orders = C [OK]

Hint: ref() compiles to the model's table name without braces [OK]

Common Mistakes:

• Leaving ref() uncompiled in SQL
• Adding extra schema prefix without config
• Using ref() as a string literal

4. You wrote this dbt model code:

select * from ref('sales')

When you run dbt, you get an error. What is the problem?

medium

A. Quotes around 'sales' should be removed

B. Model name 'sales' does not exist

C. ref() cannot be used inside select statements

D. Missing double curly braces around ref()

Solution

1. Step 1: Check the syntax of ref() usage

   In dbt, ref() must be wrapped in double curly braces to be interpreted as Jinja code.

2. Step 2: Identify the error cause

   The code uses ref('sales') without {{ }}, so dbt treats it as plain text, causing an error.

3. Final Answer:

   Missing double curly braces around ref() -> Option D

4. Quick Check:

   Use {{ ref('model') }} not ref('model') alone = D [OK]

Hint: Always wrap ref() in {{ }} to avoid errors [OK]

Common Mistakes:

• Forgetting {{ }} around ref()
• Assuming ref() works without Jinja
• Removing quotes from model name

5. You have two models: customers and orders. You want to create a new model customer_orders that joins these two. Which is the best way to use ref() to ensure correct dependencies and flexible naming?

hard

A. select c.customer_id, o.order_id from customers c join orders o on c.customer_id = o.customer_id

B. select c.customer_id, o.order_id from {{ ref('customers') }} c join {{ ref('orders') }} o on c.customer_id = o.customer_id

C. select c.customer_id, o.order_id from 'customers' c join 'orders' o on c.customer_id = o.customer_id

D. select c.customer_id, o.order_id from ref('customers') c join ref('orders') o on c.customer_id = o.customer_id

Solution

1. Step 1: Use ref() with correct Jinja syntax for both models

   To link models and ensure dbt knows dependencies, use {{ ref('model_name') }} for both customers and orders.

2. Step 2: Avoid hardcoding table names or missing Jinja syntax

   Options A and C hardcode names or use quotes incorrectly. select c.customer_id, o.order_id from ref('customers') c join ref('orders') o on c.customer_id = o.customer_id misses curly braces, so it won't compile.

3. Final Answer:

   select c.customer_id, o.order_id from {{ ref('customers') }} c join {{ ref('orders') }} o on c.customer_id = o.customer_id -> Option B

4. Quick Check:

   Use {{ ref('model') }} for all dependencies = B [OK]

Hint: Use {{ ref('model') }} for all model references [OK]

Common Mistakes:

• Hardcoding table names instead of using ref()
• Forgetting curly braces around ref()
• Using quotes incorrectly around model names