How to write a sql statement to find the first occurrence of a non zero value?

Question

Write the prototype function in C: char * my_strchr (char * arr, char c);

The function should return the cursor to the first occurrence of the forwarded character in the character sequence or NULL if the forwarded character was not found.

i came up with solution also but it has to be string :

char *my_strchr(char *arr,char c)
{
int i=0;
char *p;
while(1)
{
if(i[arr] == c){p = i[arr];return p;break;}
if(i[arr] == '\0'){p= NULL;return p;break;}
i++;
}}

Answer 1

There is a slight chance the column "a" has a value of 0 which is not null. In that case, you will loose the information. There is another way of searching the first not null value of a column:

select column_name from table_name where column_name is not null and rownum<2;