Power query editor questions
Realized we haven't used much of power query editor, may I know what is the different between loading the data and editing those tables normally VS using power query to edit?
When is the best situation to use power query instead?
Power Query is our playground where we decide how we want our data to be shaped. Let's say you only want to import certain number of columns from the dataset or you want to merge two columns into one or have your sales figures multiplied by 1.4. Power Query is the place to do it because it applies these steps on the way we get our data so inside Power BI we only get what we asked for. This makes our model lighter and perform better.
Using DAX we can do some of these transformations outside Power Query, but bear in mind that Power BI will store the custom columns which is not the best practice because we are duplicating our data by creating more columns on top of the existing ones.
Loading Data and Editing Tables Normally:
When you load data without using Power Query, you're taking everything that's in your data source and bringing it directly into Power BI.
Editing tables normally means making changes to your data after it's already in Power BI. You might delete some columns or change values, but this doesn't affect how the data was originally loaded.
Using Power Query to Edit:
Power Query is like a creative workshop for your data before it enters Power BI. It's where you decide exactly what you want to include, exclude, or change in your data.
For example, imagine you have a table with sales data, and you only want to see certain columns, or you want to combine two columns into one (like merging "Date" and "Time" into a single "DateTime" column).
Power Query lets you apply these changes before the data even gets into Power BI. This way, you're only bringing in the data you really need, making your Power BI model more efficient and faster.
When to Use Power Query:
Use Power Query when you want to shape your data before it enters Power BI. If you have specific requirements like selecting certain columns, filtering rows, or creating new calculated columns, Power Query is the tool for the job.
It's especially useful when dealing with large datasets because it helps keep your Power BI model focused on the essential information, improving performance.
While some transformations can be done later using DAX (Data Analysis Expressions, a formula language in Power BI), Power Query is preferred for many tasks to keep your model clean and efficient.
Why Power Query is Useful:
Power Query helps you prepare your data in a way that's tailor-made for your analysis. It's like a filter that ensures only the relevant, transformed data enters Power BI.
If you make changes in Power BI directly, you might end up with unnecessary columns or duplicated data, which can slow things down. Power Query helps you avoid this by letting you shape your data precisely before it gets loaded.
In summary, Power Query is your data crafting workshop, where you mold and shape your data to fit your needs before it enters the Power BI stage. This not only makes your analysis more accurate but also makes your Power BI reports run smoother and faster.