Using instr and substr

[annoji]

Hi i am new to this forum
and i wanted to know how to find a longest running charecter in string
for example if i have a string like
'aaabbbabcccccdcaa'
since c is a longest running charecter i should get output as 'c'
can anybody help me to write this store procedure

[frozenmist]

Hi Annoji,
You can have variables to store a character value (cval) and a variable to store the length (clen)(these should store the max running characters information till the current character)
eg: if aaaaabbcccccccccccc
is the string and you have started counting c's. then cval= 'a' and clen= 5.
and one more to store the current character count
Start a loop . set the current character count to 0.take the letters in the string one by one. (this can be done using substring) . then compare it with the previous letter. If equal then increment the current count. When it becomes unequal compare the count with the max count so far.
If the current count is more then assign the respective values to cval and clen.
Continue loop till string length is finished.

This is an algorithm.
Please try to implement this.
In case of any queries please revert back.
If you have doubt in SQL, please post the code you have.

Cheers