# # check errors # WITH RECURSIVE cte AS ( SELECT 1 AS a UNION ALL SELECT NULL FROM cte WHERE a IS NOT NULL) CYCLE a, a RESTRICT SELECT * FROM cte; ERROR 42S21: Duplicate column name 'a' WITH RECURSIVE cte AS ( SELECT 1 AS a UNION ALL SELECT NULL FROM cte WHERE a IS NOT NULL) CYCLE b RESTRICT SELECT * FROM cte; ERROR 42S22: Unknown column 'b' in 'CYCLE clause' WITH cte AS ( SELECT 1 AS a UNION ALL SELECT NULL FROM cte WHERE a IS NOT NULL) CYCLE b RESTRICT SELECT * FROM cte; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'CYCLE b RESTRICT SELECT * FROM cte' at line 4 # # A degenerate case # WITH RECURSIVE cte AS ( SELECT 1 AS a, 2 as b) CYCLE b RESTRICT SELECT * FROM cte; a b 1 2 # # A simple case # WITH RECURSIVE cte AS ( SELECT 1 AS a, 2 as b UNION ALL SELECT 2, 2 FROM cte WHERE a IS NOT NULL) CYCLE b RESTRICT SELECT * FROM cte; a b 1 2 # # MDEV-20632 case (with fixed syntax) # create table t1 (from_ int, to_ int); insert into t1 values (1,2), (1,100), (2,3), (3,4), (4,1); WITH RECURSIVE cte (depth, from_, to_) as ( SELECT 0,1,1 UNION SELECT depth+1, t1.from_, t1.to_ FROM t1, cte WHERE t1.from_ = cte.to_ ) CYCLE from_, to_ RESTRICT select * from cte; depth from_ to_ 0 1 1 1 1 2 1 1 100 2 2 3 3 3 4 4 4 1 create view v1 as WITH RECURSIVE cte (depth, from_, to_) as ( SELECT 0,1,1 UNION SELECT depth+1, t1.from_, t1.to_ FROM t1, cte WHERE t1.from_ = cte.to_ ) CYCLE from_, to_ RESTRICT select * from cte; show create view v1; View Create View character_set_client collation_connection v1 CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS with recursive cte(`depth`,`from_`,`to_`) as (select 0 AS `depth`,1 AS `from_`,1 AS `to_` union select `cte`.`depth` + 1 AS `depth+1`,`t1`.`from_` AS `from_`,`t1`.`to_` AS `to_` from (`t1` join `cte`) where `t1`.`from_` = `cte`.`to_`) CYCLE `from_`,`to_` RESTRICT select `cte`.`depth` AS `depth`,`cte`.`from_` AS `from_`,`cte`.`to_` AS `to_` from `cte` latin1 latin1_swedish_ci select * from v1; depth from_ to_ 0 1 1 1 1 2 1 1 100 2 2 3 3 3 4 4 4 1 delete from t1; insert into t1 values (1,2), (1,NULL), (NULL,NULL), (NULL, 1); select * from v1; depth from_ to_ 0 1 1 1 1 2 1 1 NULL drop view v1; drop table t1; # # A simple blob case # create table t1 (a int, b text); insert into t1 values (1, "a"); WITH RECURSIVE cte AS ( SELECT a, b from t1 UNION ALL SELECT a, b FROM cte WHERE a IS NOT NULL) CYCLE b RESTRICT SELECT * FROM cte; a b 1 a drop table t1; # # check bit types # create table t1 (from_ bit(3), to_ bit(3)); insert into t1 values (1,2), (1,7), (2,3), (3,4), (4,1); WITH RECURSIVE cte (depth, from_, to_) as ( SELECT 0,1,1 UNION SELECT depth+1, t1.from_, t1.to_ FROM t1, cte WHERE t1.from_ = cte.to_ ) CYCLE from_, to_ RESTRICT select * from cte; depth from_ to_ 0 1 1 1 1 2 1 1 7 2 2 3 3 3 4 4 4 1 drop table t1; # # check bit types with BLOBs (TEXT) # create table t1 (from_ bit(3), to_ bit(3), load_ text); insert into t1 values (1,2,"A"), (1,7,"A"), (2,3,"A"), (3,4,"A"), (4,1,"A"); WITH RECURSIVE cte (depth, from_, to_, load_) as ( SELECT 0,1,1,"A" UNION SELECT depth+1, t1.from_, t1.to_, t1.load_ FROM t1, cte WHERE t1.from_ = cte.to_ ) CYCLE from_, to_, load_ RESTRICT select * from cte; depth from_ to_ load_ 0 1 1 A 1 1 2 A 1 1 7 A 2 2 3 A 3 3 4 A 4 4 1 A insert into t1 values (4,1,"B"); WITH RECURSIVE cte (depth, from_, to_, load_) as ( SELECT 0,1,1,"A" UNION SELECT depth+1, t1.from_, t1.to_, t1.load_ FROM t1, cte WHERE t1.from_ = cte.to_ ) CYCLE from_, to_, load_ RESTRICT select * from cte; depth from_ to_ load_ 0 1 1 A 1 1 2 A 1 1 7 A 2 2 3 A 3 3 4 A 4 4 1 A 4 4 1 B drop table t1;