little-brother

static void square (sqlite3_context *ctx, int argc, sqlite3_value **argv) {
	int type = sqlite3_value_type(argv[0]);
	double d = sqlite3_value_double(argv[0]);	
	
	switch (type) {
		case SQLITE_NULL:
			sqlite3_result_null(ctx);
			break;
			
		case SQLITE_INTEGER:			

little-brother

void odd (sqlite3_context *ctx, int argc, sqlite3_value **argv){		
	int *pCounter = (int*)sqlite3_get_auxdata(ctx, 0);
	if (pCounter == 0) {
		pCounter = sqlite3_malloc(sizeof(*pCounter));
		if (pCounter == 0) 
			return sqlite3_result_error_nomem(ctx);
		
		*pCounter = sqlite3_value_type(argv[0]) == SQLITE_NULL ? 0 : sqlite3_value_int(argv[0]);
		sqlite3_set_auxdata(ctx, 0, pCounter, sqlite3_free);
	} else {

little-brother

// gcc main.c sqlite3.c -o main.exe
#include <stdio.h>
#include "sqlite3.h"

static void square (sqlite3_context *ctx, int argc, sqlite3_value **argv) {
	int type = sqlite3_value_type(argv[0]);
	double d = sqlite3_value_double(argv[0]);	
	
	switch (type) {
		case SQLITE_NULL:

little-brother

// gcc main.c sqlite3.c -o main.exe
#include <stdio.h>
#include "sqlite3.h"

int main() {
	sqlite3* db;
	if (SQLITE_OK != sqlite3_open_v2(":memory:", &db, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_URI, NULL)) {
		printf("Error: can't open a database");
		return -1;
	}

little-brother

// gcc -shared aggavg.c -o aggavg.dll -s -static
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1

typedef struct agg_state {
	int cnt;
	double sum;
} agg_state;

static void avg_step (sqlite3_context *ctx, int argc, sqlite3_value **argv) {

little-brother

// gcc -shared aggsum.c -o aggsum.dll -s -static
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1

static void sum_step (sqlite3_context *ctx, int argc, sqlite3_value **argv) {
	double* total = (double*)sqlite3_aggregate_context(ctx, sizeof(double));
	if (total == NULL) 
		return sqlite3_result_error_nomem(ctx);

	*total += sqlite3_value_double(argv[0]);	

little-brother

// gcc -shared vtab.c -o vtab.dll -s -static
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#include <string.h>

typedef struct vtab_vtab vtab_vtab;
struct vtab_vtab {
	sqlite3_vtab base;
};

little-brother

// gcc -shared vtab.c -o vtab.dll -s -static
// create virtual table t using vtab(4); -- 4 is a column count
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

typedef struct vtab_vtab vtab_vtab;

little-brother

// gcc -shared vtab.c -o vtab.dll -s -static
// select * from vtab('D:/1.txt')
// select line from vtab where path = 'D:/1.txt'
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#define MAX_LINE_SIZE 1024

little-brother

/* 
	Build
	gcc.exe -Wall -O2  -c main.c -o obj\main.o
	gcc.exe -Wall -O2  -c sqlite3.c -o obj\sqlite3.o
	gcc.exe -o watcher.exe obj\main.o obj\sqlite3.o  -s 
	
	Usage example
	watcher -d "D:/my.sqlite" -q "select * from t order by 1 desc limit 10" - t 2
*/
#include <stdbool.h>