Data Types in Tableau

Tableau is an easy-to-use Business Intelligence tool widely used for data visualization. One of it’s important features is how it classifies data into specific types. Every value in a dataset belongs to a data type.

For example, characters ("Hello"), integers (108) or floating-point numbers (1.854). Tableau automatically detects the data type of each field when data is uploaded and assigns it accordingly.

1. String Data Type

A string is a collection of characters enclosed in single or double quotes. String data types can be divided into two categories:

• Char: Stores alphanumeric values with a fixed length. If we enter a value longer than the defined length, Tableau will return an error.
• Varchar: Stores alphanumeric values with a variable length. This provides more flexibility, as there is no strict restriction on the number of characters.

2. Numeric Data Type

The numeric type includes both integers and floating-point numbers. While people often prefer integers for calculations, the system also supports floating-point numbers. Tableau provides functions such as ROUND() to handle decimal precision and simplify floating-point values.

3. Date and Time Data Type

Tableau supports a wide range of date and time formats, such as:

• dd-mm-yy
• mm-dd-yyyy
• yyyy-mm-dd

Time values can represent decades, years, quarters, months, days, hours, minutes or seconds. When a date or time value is entered, Tableau automatically categorizes it as either Date or Date & Time depending on the format.

4. Boolean Data Type

The Boolean type stores logical values:

• TRUE
• FALSE

Boolean fields are often the result of relational calculations. If the outcome of a calculation is unknown, Tableau assigns a NULL value.

5. Geographic or Spatial Values Data Type

Geographic data is used in map visualizations. Examples include:

• Country names
• State or region names
• Cities
• Postal codes

When Tableau recognizes a field as geographic, it enables us to create maps automatically.

6. Cluster or Mixed Data Type

Sometimes datasets contain values with a mixture of data types. For example, a field may have both numeric and text values. In such cases, Tableau generally assigns the field a String (Text) data type.

In such situations, we can either:

• Clean and standardize the field manually
• Or convert the values into a consistent data type for accurate analysis