Returns the specified number of characters from the start of a text string.
|text||The text string containing the characters you want to extract, or a reference to a column that contains text.|
|num_chars||(optional) The number of characters you want LEFT to extract; if omitted, 1.|
A text string.
Whereas Microsoft Excel contains different functions for working with text in single-byte and double-byte character languages, DAX works with Unicode and stores all characters as the same length; therefore, a single function is enough.
This function is not supported for use in DirectQuery mode when used in calculated columns or row-level security (RLS) rules.
The following example returns the first five characters of the company name in the column [ResellerName] and the first five letters of the geographical code in the column [GeographyKey] and concatenates them, to create an identifier.
If the num_chars argument is a number that is larger than the number of characters available, the function returns the maximum characters available and does not raise an error. For example, the column [GeographyKey] contains numbers such as 1, 12 and 311; therefore the result also has variable length.