how to get first three characters from a string in sql code example

Example 1: sql server substring

SELECT SUBSTRING('SQL Tutorial', 1, 3) AS ExtractString;

Example 2: reading from right to left from string find first special characters in sql

DECLARE @strvalue varchar(20) = 'SDADH/SDKDS/SD/UIO-123/WEA/456'
SELECT REVERSE(SUBSTRING(REVERSE(@strvalue),0,CHARINDEX ('/',REVERSE(@strvalue))))