Prepare a SQL statement

Property definitions

sqlite3 $ NativeSqlite3 :: prepare
	# Prepare a SQL statement
	fun prepare(sql: CString): NativeStatement `{
		sqlite3_stmt *stmt;
		int res = sqlite3_prepare_v2(self, sql, -1, &stmt, 0);
		if (res == SQLITE_OK)
			return stmt;
		else
			return NULL;
	`}
lib/sqlite3/native_sqlite3.nit:170,2--178,3