Adds two values together.
byte? ADD(byte? a, byte? b)
short? ADD(short? a, short? b)
int? ADD(int? a, int? b)
long? ADD(long? a, long? b)
Single? ADD(Single? a, Single? b)
double? ADD(double? a, double? b)
double? ADD(double? a, decimal? b)
decimal? ADD(decimal? a, double? b)
decimal? ADD(decimal? a, decimal? b)
ADD(2,2)
Will return '4'.