How to count instances of character in SQL Column

Question

I have an sql column that is a string of 100 \'Y\' or \'N\' characters. For example:

YYNYNYYNNNYYNY...

What is the easiest way

Answer 1

for example to calculate the count instances of character (a) in SQL Column ->name is column name '' ( and in doblequote's is empty i am replace a with nocharecter @'')

select len(name)- len(replace(name,'a','')) from TESTING

select len('YYNYNYYNNNYYNY')- len(replace('YYNYNYYNNNYYNY','y',''))