Dates and Times
Dates in Relational Data Sources
For relational
data sources, dates and times are automatically placed in the Dimensions area
of the Data pane and are identified by the date or date-time
icon. For example, the Order
Date and Ship Date dimensions
from an Excel data source are shown below.
When you place a relational date on a shelf, the field name is automatically modified to reflect the default date level. Tableau defines the default date level to be the level at which there are multiple instances. For example, if the date field includes multiple years, the default level is year. However, if the date field contains data for just one year but includes multiple months, then the default level is month.
If you don’t want Tableau to automatically select a date level and would rather have a date dimension be a continuous field, you can right-click (control-click on Mac) the field in the Data pane and select Convert to Continuous. The dimension then turns green in the Data pane; now when you use that dimension in a view, it will be continuous. You can easily revert back by selecting Convert to Discrete from the field’s context menu in the Data pane. You can also convert a field in the view to continuous while it is on a shelf by selecting Continuous on its context menu (which you can see when you right-click (control-click on Mac) the field). The field on the shelf turns green but the field in the Data pane is still discrete.