count rows result set data

Question

I have a SELECT query, and I would like to know the number of rows.

I tried:

sqlite3_data_count(statement);

but it always returns 0

Answer 1

SQLite computes the result rows on the fly, so you the number of rows is not known before you have actually read all those rows.

You could execute a separate query SELECT COUNT(*) FROM (original query), but this would mean that the query is executed twice.

Instead, you should use a data structure that grows dynamically.

Answer 2

sqlite3_data_count is not counts row but counts columns.

sqlite3_data_count returns the number of values (columns) of the currently executing statement. With no results it returns 0.
LINK HERE
You can verify it in .h doc for sqlite3_data_count().

To count number of rows you can use following:

SELECT COUNT(*) FROM "mytable"