Question

Please can anyone tell me why we write NULL in the fifth parameter below?

if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK)

Thanks in advance.

Answer 1

As long as your sql has only one statement, you don’t need to use the fifth parameter. When sql has more than one statement, you can receive a pointer to the beginning of the next statement.
For example:

const char* sql =
  "DROP TABLE price_list;"
  "CREATE TABLE price_list ( item TEXT, price INTEGER)";
while ( *sql ) {
  sqlite3_stmt* statement;
  sqlite3_prepare_v2(db, sql, -1, &statement, &sql);
  sqlite_step(statement);
  sqlite_finalize(statement);
}