SQLite Data Flow

Applications interact with SQLite through three primary functions that wrap the full pipeline:

int sqlite3_exec(
  sqlite3 *db,                /* The database on which the SQL executes */
  const char *zSql,           /* The SQL to be executed */
  sqlite3_callback xCallback, /* Invoke this callback routine */
  void *pArg,                 /* First argument to xCallback() */
  char **pzErrMsg             /* Write error messages here */
){
  int rc = SQLITE_OK;
  const char *zLeftover;
  sqlite3_stmt *pStmt = 0;

  sqlite3_mutex_enter(db->mutex);
  while( rc==SQLITE_OK && zSql[0] ){
    rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, &zLeftover);
    if( rc!=SQLITE_OK ) continue;
    while( 1 ){
      rc = sqlite3_step(pStmt);          // ← drives the VDBE
      if( xCallback && SQLITE_ROW==rc ){
        /* invoke user callback with row data */
      }
      if( rc!=SQLITE_ROW ) break;
    }
    sqlite3_finalize(pStmt);
    zSql = zLeftover;
  }
  ...
}