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Diffstat (limited to 'mysql-test/main/cte_recursive.test')
-rw-r--r-- | mysql-test/main/cte_recursive.test | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/mysql-test/main/cte_recursive.test b/mysql-test/main/cte_recursive.test index 0ed9c2d56e3..483e1ea8c7a 100644 --- a/mysql-test/main/cte_recursive.test +++ b/mysql-test/main/cte_recursive.test @@ -1200,6 +1200,40 @@ select * from my_ancestors; drop table my_ancestors; +# +# MDEV-17967 Add a solution of the 8 queens problem to the regression test for CTE +# +# adapted to MariaDB from https://rosettacode.org/wiki/N-queens_problem#SQL +# +let $N=4; # 8 takes too long for a test +eval WITH RECURSIVE + positions(i) AS ( + VALUES(0) + UNION SELECT ALL + i+1 FROM positions WHERE i < $N*$N-1 + ), + solutions(board, n_queens) AS ( + SELECT REPEAT('-', $N*$N), 0 + FROM positions + UNION + SELECT + concat(substr(board, 1, i),'*',substr(board, i+2)),n_queens + 1 AS n_queens + FROM positions AS ps, solutions + WHERE n_queens < $N + AND substr(board,1,i) != '*' + AND NOT EXISTS ( + SELECT 1 FROM positions WHERE + substr(board,i+1,1) = '*' AND + ( + i % $N = ps.i % $N OR + i div $N = ps.i div $N OR + i div $N + (i % $N) = ps.i div $N + (ps.i % $N) OR + i div $N - (i % $N) = ps.i div $N - (ps.i % $N) + ) + ) + ) +SELECT regexp_replace(board,concat('(',REPEAT('.', $N),')'),'\\\\1\\n') n_queens FROM solutions WHERE n_queens = $N; + --echo # --echo # MDEV-10883: execution of prepared statement from SELECT --echo # with recursive CTE that renames columns |