to search a pattern with in an expression and to get the position use the following sql query

to search a pattern with in an expression and to get the position
use the following sql query

SELECT PATINDEX('%BC%','ABCD')
SELECT PATINDEX('%[s,S]erver%', 'Microsoft SQL Server SQL')
SELECT PATINDEX('%[1-9]163%', '12345A916303SQL')
SELECT PATINDEX('%[.]%', 'sample.xls')

if returns 0, no pattern found
if returns >0, pattern found