sqlite3 uses sqlite3_exec, whose prototype is as follows:

C
int sqlite3_exec(
	sqlite3*,                                  /* An open database */
	const char *sql,                           /* SQL to be evaluated */
	int (*callback)(void*,int,char**,char**),  /* Callback function */
	void *,                                    /* 1st argument to callback */
	char **errmsg                              /* Error msg written here */
);

One of the parameters is of type callback. The queried data is handled inside the callback.

I've always been used to the convention that 0 means false and anything non-zero means true. So, following that habit, I returned 1 to mean true.

At first, everything worked perfectly: creating tables, inserting data, querying a result set with just one row — until one day, I queried three rows... and got error code (4) (error code list).

It said: 

 Callback routine requested an abort

WTF — judging by the name, did my query go wrong?

I debugged the query every which way. Then, one time, just on a whim, I set the callback function's return value to 0 — and it passed.

..............................