This post is a part of the PL-300: Microsoft Power BI Data Analyst Exam Prep Hub; and this topic falls under these sections:
Prepare the data (25–30%)
   --> Get or connect to data
      --> Create and Modify Parameters

Note that there are 10 practice questions (with answers and explanations) for each section to help you solidify your knowledge of the material. Also, there are 2 practice tests with 60 questions each available on the hub below the exam topics section.

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As you prepare for the PL-300: Microsoft Power BI Data Analyst exam, one important skill to master is using parameters in Power Query to build flexible, reusable, and dynamic data connections and transformations. Parameters help you abstract static values—such as server names, file paths, or filter values—and manage them in a centralized way. Microsoft Learn

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What Are Parameters in Power BI?

A parameter is a named value that you can use in Power Query to influence how queries run. Instead of hard-coding values directly into your query steps, a parameter lets you declare the value once and reference it throughout your queries so you can:

• Change values globally without editing each query step.
• Switch between environments (Dev, Test, Prod) easily.
• Apply consistent filters or thresholds.
• Support dynamic filtering and modular query design.

In many ways, parameters act like variables in the Power Query (M) engine—reusable building blocks you can plug into various parts of your query logic. Microsoft Learn

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Where You Use Parameters

Parameters are especially useful when connecting and shaping data:

At the data source level

• Define the server, database, folder, or file path.
• Change the current environment without rewriting source steps.

In query logic

• Filter tables based on parameter values.
• Customize operations like date range filters or limit values.

For reusability

• Use the same parameter value across multiple queries, reducing maintenance.
• Make Power BI solutions easier to support if data locations change. Microsoft Learn

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How to Create Parameters

In Power BI Desktop:

1. Go to Home → Transform data → Transform data to open Power Query Editor.
2. In the Power Query Editor, choose Manage Parameters → New Parameter.
3. In the Manage Parameters dialog, provide:
   • Name (meaningful identifier for the parameter)
   • Description (optional, useful for documentation)
   • Required (whether a value must be entered)
   • Type (Text, Number, Date, etc.)
   • Suggested values (optional: helps users pick from list, default, etc.)
   • Current value (the value Power Query uses when the parameter is applied) Microsoft Learn

Once created, the parameter appears in Power Query as its own query and can be referenced in other queries.

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Example Uses of Parameters

Here are typical scenarios where parameters are valuable:

1. Dynamic Data Source Connection

If a report needs to point to Development in one workflow and Production in another, you can create parameters for server name and database name, then reference them in the data source step.

This avoids hard-coding connection strings and simplifies environment switches without editing M code. 3Cloud

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2. Reusable Filters

Suppose you want to filter a sales table by a minimum sales amount that might change often. Instead of editing the filter step directly each time, you use a parameter called MinSalesThreshold. If business needs change, you update the parameter once, and all queries referencing it update accordingly. Microsoft Learn

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3. Parameter-Driven Queries

You can embed a parameter into custom functions or use it directly in the M query logic (e.g., in Table.SelectRows), making your query logic adaptable without editing M code every time. Microsoft Learn

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Modifying Parameters

Once a parameter is created:

• Return to Manage Parameters in Power Query Editor to change metadata (name, description, type).
• Update the Current Value to change how queries refresh with different values.
• If you change suggested values, you may also redefine the list of allowed inputs.

Changing a parameter’s current value typically triggers a refresh of any queries that reference it, applying the new logic or sources immediately. Microsoft Learn

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Best Practices for Parameters

Use clear names and descriptions
Someone else reviewing your model should immediately understand the purpose of each parameter.

Keep parameter types consistent
Ensure the data type matches how you intend to use it in queries to avoid type mismatch errors.

Leverage suggested values
If a parameter is intended to allow only certain options (e.g., environment names), defining suggested values improves usability and reduces errors.

Document your parameters
Include descriptions so others know what each parameter does and why it exists. Microsoft Learn

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How This Appears on the PL-300 Exam

You may see exam scenarios such as:

• “You need to allow end users to easily switch data sources without editing M code.”
• “Modify a query so that multiple environments use the same report with different connection settings.”
• “Filter the data using a parameter and explain how the data refresh behaves.”

To answer confidently:

• Know how to create and configure parameters.
• Understand how parameters change the behavior of queries and filtering.
• Recognize when parameters simplify maintenance and governance.

This skill not only helps you build robust and flexible Power BI solutions but also aligns with the Prepare the data objectives in the PL-300 exam. Microsoft Learn

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Practice Questions

Go to the Practice Exam Questions for this topic.