MDEV-22830:SQL_CALC_FOUND_ROWS not working properly for single SELECT for DUALbb-10.1-MDEV-22830

In case of SELECT without tables which returns either 0 or 1 rows,
JOIN::exec_inner() did not check if the flag representing SQL_CALC_FOUND_ROWS
is set or not and send_records was direclty assigned 0. So SELECT FOUND_ROWS()
was giving 0 in the output. Now it checks if the flag is set, if it is set
send_record=1 else 0. 1 is the number of rows that could have been sent
to the client if the SELECT query had SQL_CALC_FOUND_ROWS.
It is 0 when no rows were sent because the SELECT query did not have
SQL_CALC_FOUND_ROWS.

1 files changed, 7 insertions, 0 deletions

diff --git a/mysql-test/t/select_found.test b/mysql-test/t/select_found.test
index 33613697722..092ffc00cdc 100644
--- a/mysql-test/t/select_found.test
+++ b/mysql-test/t/select_found.test
@@ -286,4 +286,11 @@ select * from t1 order by c1 limit 2,1;
 select found_rows();
 select sql_calc_found_rows * from t1 order by c1 limit 2,1;
 select found_rows();
+
+#
+# MDEV-22830 SQL_CALC_FOUND_ROWS not working properly for single SELECT for DUAL
+#
+SELECT SQL_CALC_FOUND_ROWS 1 FROM DUAL WHERE 0;
+SELECT FOUND_ROWS();
+
 drop table t1;