Chapter 1 of 4 · Microsoft PL-300
Prepare the data
Connecting to sources, storage modes, profiling, cleaning, shaping, merging and loading data with Power Query.
- 8topics
- 37 minfast track
- 3diagrams and exhibits
- 25–30%of the exam
Topics in this chapter
Take them in order, or jump to the one you need.
- 1Connecting to Data and Data Source SettingsPL-300 connecting to data: choosing connectors, using a shared semantic model, editing credentials in data source settings and…5 min
- 2Storage Modes and ParametersPL-300 storage modes: choose between Import, DirectQuery, Dual, live connection and Direct Lake, and create Power Query…Diagram5 min
- 3Profiling Data and Column StatisticsPL-300 data profiling: use column quality, column distribution and column profile in Power Query, read data statistics and check…4 min
- 4Cleaning Data and Resolving ErrorsPL-300 data cleaning: handle nulls, duplicates and inconsistent text, fix type conversion errors and resolve import errors such…5 min
- 5Data Types and Column TransformationsPL-300 data types and columns: pick the right Power Query data type, change type with locale, and build columns with column from…4 min
- 6Grouping, Pivoting and Semi Structured DataPL-300 reshaping data: group and aggregate rows, pivot, unpivot and transpose tables, and convert JSON and XML into tables in…4 min
- 7Reference, Duplicate, Merge and Append QueriesPL-300 combining queries: reference versus duplicate, six merge join kinds, append queries, and the effect each choice has on…Diagram5 min
- 8Fact and Dimension Tables, Keys and Load SettingsPL-300 star schema preparation: create fact and dimension tables, choose keys for relationships, and control loading with enable…Diagram5 min
About this chapter
What this chapter covers
Every Power BI report starts with data that is rarely ready to use. This domain is worth 25 to 30 percent of the exam. It covers connecting to data sources and shared semantic models, choosing between Import, DirectQuery and Direct Lake, profiling and cleaning data, and shaping it with Power Query so that it loads as a clean star schema.
You need to know which Power Query command solves which problem, and which choice at connection time affects everything that comes later.
How the topics fit together
- Connecting to data and data source settings covers connectors, shared semantic models, credentials and privacy levels.
- Storage modes and parameters covers Import, DirectQuery, Dual, Direct Lake and Power Query parameters.
- Profiling data and column statistics covers the three profiling views and column properties.
- Cleaning data and resolving errors covers nulls, inconsistent values and import errors.
- Data types and column transformations covers types, new columns and column from examples.
- Grouping, pivoting and semi structured data covers group by, pivot, unpivot, transpose, JSON and XML.
- Reference, duplicate, merge and append queries covers combining queries and what each choice costs.
- Fact and dimension tables, keys and load settings covers star schema design, relationship keys and enable load.
Power Query steps are recorded in order. When a question describes a problem in the data, ask which single step would fix it with the least side effect.
How to use these pages
Each topic page has the same shape, so you can skim for what you need.
- What it is: the idea in plain words.
- How it works: the mechanism, with examples and tables.
- What to remember for the exam: the facts to memorise and how questions are phrased.
- Common mistakes: the classic traps.
- Check yourself: three questions to test your understanding.
Ready for more practice?
The full Microsoft PL-300 question bank has 657 questions, with timed practice exams and an explanation for every answer.
This study guide is independent and is not affiliated with, endorsed by, or sponsored by Microsoft. Vendor names, certification names and exam codes are trademarks of their respective owners and are used for identification only.