Data Analysis Expressions (DAX) is a language used in Analysis Services, Power BI, and Power Pivot in Excel. DAX formulas include functions, operators, and values to perform advanced calculations and queries on data in related tables and columns in tabular data models.
The Basics of DAX for Data Analysis
DAX is a powerful language that can be used to create dynamic and informative reports that can help you make better decisions. By understanding the basics of Data Analysis Expressions, you can:
- Perform advanced calculations on data
- Create dynamic filters and calculations
- Create measures that can be used in reports
- Build tabular data models
Creating DAX Tables, Columns, and Measures
Data Analysis Expression tables are similar to Excel tables, but they can contain calculated columns and measures. Calculated columns are formulas that are applied to all rows in a column, while measures are formulas that are calculated based on data in multiple columns.
To create a DAX table, right-click on the Tables pane and select New Table. In the Create Table dialog box, enter a name for the table and select the columns that you want to include.
To create a calculated column, right-click on the Columns pane and select New Calculated Column. In the Create Calculated Column dialog box, enter a name for the column and type in the formula that you want to use.
To create a measure, right-click on the Measures pane and select New Measure. In the Create Measure dialog box, enter a name for the measure and type in the formula that you want to use.
Executing DAX Operators
Data Analysis Expressions operators are used to perform calculations on data. Some common DAX operators include:
- Arithmetic operators: These operators are used to perform basic arithmetic operations, such as addition, subtraction, multiplication, and division.
- Comparison operators: These operators are used to compare two values and return a Boolean value (true or false).
- Logical operators: These operators are used to combine Boolean values and return a Boolean value.
- Text operators: These operators are used to manipulate text strings.
Read more –> Data Analysis Roadmap 101: A step-by-step guide
Discussing Basic Math & Statistical Functions
DAX includes a wide variety of mathematical and statistical functions that can be used to perform calculations on data. Some common mathematical and statistical functions include:
- SUM: This function returns the sum of all values in a column or range.
- AVERAGE: This function returns the average of all values in a column or range.
- COUNT: This function returns the number of non-empty values in a column or range.
- MAX: This function returns the maximum value in a column or range.
- MIN: This function returns the minimum value in a column or range.
Implementing Date & Time Functions
Data Analysis Expressions includes many date and time functions that can be used to manipulate date and time data. Some common date and time functions include:
- DATEADD: This function adds a specified number of days, months, years, or hours to a date.
- DATEDIFF: This function returns the number of days, months, years, or hours between two dates.
- TODAY: This function returns the current date.
- NOW: This function returns the current date and time.
Using Text Functions
DAX includes several text functions that can be used to manipulate text data. Some common text functions include:
- LEFT: This function returns the leftmost characters of a string.
- RIGHT: This function returns the rightmost characters of a string.
- MID: This function returns a substring from a string.
- LEN: This function returns the length of a string.
- TRIM: This function removes leading and trailing spaces from a string.
Using calculate & filter functions
Data Analysis Expressions includes several calculate and filter functions that can be used to create dynamic calculations and filters. Some common calculate and filter functions include:
- CALCULATE: This function allows you to create dynamic calculations that are based on the current context.
- FILTER: This function allows you to filter data based on a condition.
Summing up Data Analysis Expressions (DAX)
Data Analysis Expressions is a powerful language that can be used to perform advanced calculations and queries on data in Analysis Services, Power BI, and Power Pivot in Excel. By understanding the basics of DAX, you can create dynamic and informative reports that can help you make better decisions.
