Before you can add a new function to use in your SQL statements with SQLite, you must first create an SQLite extension library. This is relatively easy to do, and the SQLite web site provides a straightforward wiki article explaining what to do.

To actually add an instr() function to SQLite, use the following code segment:

   1: void sqlite3_instr(sqlite3_context* pContext, int argc, sqlite3_value** argv)

   2: {

   3:     const char *str1 = (const char *) sqlite3_value_text(argv[0]);

   4:     const char *str2 = (const char *) sqlite3_value_text(argv[1]);

   5:  

   6:     char *p = strstr(str1, str2);

   7:     int nResult = 0;

   8:  

   9:     if(p != NULL)

  10:     {

  11:         nResult = p - str1 + 1;

  12:     }

  13:  

  14:     sqlite3_result_int(pContext, nResult);

  15: }

And that’s really all you need.