This blog can help you to create alphabet index like : A,B,C,D . . . Z, AA, AB . . . AZ, BA, BB . . . and so on like column in Excel.

 In PHP, we can get next letter of given alphabet simply increment by one. As you show as follow:

But if you want same thing in MySQL for incremented column with infinite alphabet index instead of numeric value then you can also get it by click Here