MID
Applies to: 
Calculated column
Calculated table
Measure
Visual calculation
Returns a string of characters from the middle of a text string, given a starting position and length.
Syntax
MID(<text>, <start_num>, <num_chars>)
Parameters
| Term | Definition |
|---|---|
| text | The text string from which you want to extract the characters, or a column that contains text. |
| start_num | The position of the first character you want to extract. Positions start at 1. |
| num_chars | The number of characters to return. |
Return value
A string of text of the specified length.
Remarks
Whereas Microsoft Excel has different functions for working with single-byte and double-byte characters languages, DAX uses Unicode and stores all characters with the same length.
Examples
The following expression,
MID("abcde",2,3))
Returns "bcd".
The following expression,
MID('Reseller'[ResellerName],1,5))
Returns the same result as LEFT([ResellerName],5). Both expressions return the first 5 letters of column, [ResellerName].