Drop Table FIND_A_TST

Create Table FIND_A_TST
(
Col1 int,
Col2 varchar(30)
)

Insert Into FIND_A_TST Values(1, 'AAA')
Insert Into FIND_A_TST Values(1, 'AAA_')
Insert Into FIND_A_TST Values(1, 'AA_A') -- Find Only This Recored
Insert Into FIND_A_TST Values(1, 'A_AA')

Select * from FIND_A_TST

-- Use Like 
Select * from FIND_A_TST
Where Col2 like '%_A';

-- Use CHARINDEX
Select * From FIND_A_TST
where CHARINDEX('_A', COL2) > 0;