create or replace table a (
cola int(10 ) primary key,
v_cola int(10 ) as (cola mod 10 ) virtual,
p_cola int(10 ) as (cola mod 10 ) persistent
) engine=innodb;
create index v_cola on a (v_cola);
create index p_cola on a (p_cola);
create or replace table b(
cola int(10 ),
v_cola int(10 ),
p_cola int(10 ),
c_cola int(10 ) as (cola + 2 ) virtual
) engine=innodb;
alter table b add constraint `p_cola_fk`
foreign key (p_cola) references a (p_cola)
on delete restrict
on update restrict;
show warnings;
Level Code Message
show create table b;
Table Create Table
b CREATE TABLE `b` (
`cola` int(10 ) DEFAULT NULL,
`v_cola` int(10 ) DEFAULT NULL,
`p_cola` int(10 ) DEFAULT NULL,
`c_cola` int(10 ) GENERATED ALWAYS AS (`cola` + 2 ) VIRTUAL,
KEY `p_cola_fk` (`p_cola`),
CONSTRAINT `p_cola_fk` FOREIGN KEY (`p_cola`) REFERENCES `a` (`p_cola`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci
alter table b add constraint `v_cola_fk`
foreign key (v_cola) references a (v_cola)
on delete restrict
on update restrict;
show warnings;
Level Code Message
show create table b;
Table Create Table
b CREATE TABLE `b` (
`cola` int(10 ) DEFAULT NULL,
`v_cola` int(10 ) DEFAULT NULL,
`p_cola` int(10 ) DEFAULT NULL,
`c_cola` int(10 ) GENERATED ALWAYS AS (`cola` + 2 ) VIRTUAL,
KEY `p_cola_fk` (`p_cola`),
KEY `v_cola_fk` (`v_cola`),
CONSTRAINT `p_cola_fk` FOREIGN KEY (`p_cola`) REFERENCES `a` (`p_cola`),
CONSTRAINT `v_cola_fk` FOREIGN KEY (`v_cola`) REFERENCES `a` (`v_cola`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci
alter table b add constraint `c_cola_fk`
foreign key (c_cola) references a (cola)
on delete restrict
on update restrict;
show warnings;
Level Code Message
show create table b;
Table Create Table
b CREATE TABLE `b` (
`cola` int(10 ) DEFAULT NULL,
`v_cola` int(10 ) DEFAULT NULL,
`p_cola` int(10 ) DEFAULT NULL,
`c_cola` int(10 ) GENERATED ALWAYS AS (`cola` + 2 ) VIRTUAL,
KEY `p_cola_fk` (`p_cola`),
KEY `v_cola_fk` (`v_cola`),
KEY `c_cola_fk` (`c_cola`),
CONSTRAINT `c_cola_fk` FOREIGN KEY (`c_cola`) REFERENCES `a` (`cola`),
CONSTRAINT `p_cola_fk` FOREIGN KEY (`p_cola`) REFERENCES `a` (`p_cola`),
CONSTRAINT `v_cola_fk` FOREIGN KEY (`v_cola`) REFERENCES `a` (`v_cola`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci
insert into a(cola) values (12 );
select * from a;
cola v_cola p_cola
12 2 2
insert into b(cola, v_cola, p_cola) values (10 ,2 ,2 );
select * from b;
cola v_cola p_cola c_cola
10 2 2 12
insert into b(cola, v_cola, p_cola) values (10 ,1 ,1 );
ERROR 23000 : Cannot add or update a child row: a foreign key constraint fails (`test`.`b`, CONSTRAINT `p_cola_fk` FOREIGN KEY (`p_cola`) REFERENCES `a` (`p_cola`))
delete from a;
ERROR 23000 : Cannot delete or update a parent row: a foreign key constraint fails (`test`.`b`, CONSTRAINT `c_cola_fk` FOREIGN KEY (`c_cola`) REFERENCES `a` (`cola`))
select * from a;
cola v_cola p_cola
12 2 2
select * from b;
cola v_cola p_cola c_cola
10 2 2 12
drop table b, a;
Messung V0.5 in Prozent C=75 H=100 G=88
¤ Dauer der Verarbeitung: 0.10 Sekunden
(vorverarbeitet am 2026-10-08)
¤
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