i have to create two tables with a bidirectional relationship, as in the figure given below.
But it always gives an error. I am using the following query for creating the tables.
CREATE TABLE IF NOT EXISTS `rpt_operation` (
`op_id` int(45) NOT NULL,
`component` int(45) NOT NULL,
`ideal_time` time NOT NULL,
`handling_time` time NOT NULL,
PRIMARY KEY (`op_id`),
INDEX (component),
FOREIGN KEY (component)
REFERENCES rpt_component(comp_id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE IF NOT EXISTS `rpt_component` (
`comp_id` int(45) NOT NULL,
`lot_code` int(60) NOT NULL,
`lot_color` varchar(60) NOT NULL,
`drawing_num` int(60) NOT NULL,
`revision_num` int(60) NOT NULL,
`operation` int(45) NOT NULL,
PRIMARY KEY (`comp_id`),
INDEX (operation),
FOREIGN KEY (operation)
REFERENCES rpt_operation(op_id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
The error appear in the line component int(45) NOT NULL of rpt_operation table.
Any help will be appreciated.
Thanks in advance
Your table structure is impossible. You can't insert any records into rpt_operation because there are no records in rpt_component for the component foreign key, and you can't insert any records into rpt_component because there are no records in rpt_operation for the operation foreign key.
If you make one or both of those fields nullable, then the table structure is still recursive, so you have to add one of the foreign keys manually, for example:
ALTER TABLE rpt_operation
ADD CONSTRAINT
FOREIGN KEY (component)
REFERENCES rpt_component(comp_id);
I would suggest you to use a linking-table to resolve this problem. This is not a viable solution and requires workarounds.
Related
THE SOLUTION IS BELOW
I have three tables like the following:
CREATE TABLE `t_arch_layer` (
`arch_layer_id` int(11) NOT NULL AUTO_INCREMENT,
`arch_layer_name` varchar(45) NOT NULL,
PRIMARY KEY (`arch_layer_id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8;
CREATE TABLE `t_tech` (
`tech_id` int(11) NOT NULL AUTO_INCREMENT,
`tech_name` varchar(45) DEFAULT NULL,
`tech_type_id` int(11) NOT NULL,
`tech_icon` text,
PRIMARY KEY (`tech_id`),
KEY `fk_t_tech_t_tech_type1_idx` (`tech_type_id`),
CONSTRAINT `fk_t_tech_t_tech_type1` FOREIGN KEY (`tech_type_id`) REFERENCES `t_tech_type` (`tech_type_id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=33 DEFAULT CHARSET=utf8;
CREATE TABLE `t_arch_layer_tech` (
`arch_layer_id` int(11) NOT NULL,
`tech_id` int(11) NOT NULL,
PRIMARY KEY (`tech_id`,`arch_layer_id`),
KEY `fk_t_layer_has_t_tech_t_tech1_idx` (`tech_id`),
KEY `fk_t_layer_has_t_tech_t_layer1_idx` (`arch_layer_id`),
CONSTRAINT `fk_t_layer_has_t_tech_t_layer1` FOREIGN KEY (`arch_layer_id`) REFERENCES `t_arch_layer` (`arch_layer_id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_t_layer_has_t_tech_t_tech1` FOREIGN KEY (`tech_id`) REFERENCES `t_tech` (`tech_id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Basically it's a tipical situation where one table use two foreign keys from another two different tables. This table stores the possible combinations between the layers and technologies so it can't store any combination of layer_id and tech_id which is not in both.
But there is a problem, I need to delete whenever I want some row from t_arch_layer_tech. This it's impossible due to the foreign keys, I know it.
My question is, is there something to use the foreign key as a reference to forbide insert values that there aren't into t_tech or t_arch_layer and also to be consider as "own fields" (I can't explain better) of the table in order to delete any row of the t_arch_layer_tech table? Delete t_tech and t_arch_layer tables to avoid the foreign keys and then set the limits into the t_arch_layer_tech is not a solution.
SOLUTION
When that error appears it's neccesary to check the DB relationships and read carefully the provided message. It seems useless but it helped me to understand what's happening with the t_arch_layer_tech FK. I was using them into another table BUT separately, not as a compound FK. This is the reason because I could insert some rows into t_arch_layer_tech and delete only specific pairs.
So, summarizing, if you are going to use FKs that exist together (as my pair "arch_layer_id, tech_id") create ONLY ONE FK which is a compound FK that uses the mentioned.
Hi i hope some one can help my problem is that when i try to add a foreign key constraint i get this error.
My database name is "hazard"
Child:
CREATE TABLE `child` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`a` INT(11) NULL DEFAULT NULL,
`b` INT(11) NULL DEFAULT NULL,
PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
Parent:
CREATE TABLE `parent` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`alfa` INT(11) NULL DEFAULT NULL,
`beta` INT(11) NULL DEFAULT NULL,
PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
Those are the create codes (using HeidiSQL)
and when i try to add a foreign key
with
ALTER TABLE CHILD MODIFY COLUMN A INT,add constraint fk_parent_child FOREIGN KEY(A) REFERENCES PARENT(ALFA);
or
ALTER TABLE CHILD add constraint fk1 foreign key (a) references parent(alfa);
I get the same error
Can't create table 'hazard.#sql-d04_53' (errno: 150)
this is happening to many of my classmates using MariaDB and mySQL
Beforehand an apology for the inconvenience and I hope you guys can help us.
Add
KEY (`alfa`)
to the parent table. "The referenced columns must be a PRIMARY KEY or a UNIQUE index." – https://mariadb.com/kb/en/mariadb/foreign-keys/
http://sqlfiddle.com/#!9/b4c12
Error 150 usually means you are updating the tables in the wrong order. That is, your first INSERT violates the FOREIGN KEY constraint that your second INSERT will fix.
In your case you are doing ALTER instead of INSERT. Swap the order of the ALTERs. If that does not work, check the data to see that you won't be violating FK constraints. If you get past that, read on...
In extreme cases, you can turn off foreign key constraints while doing the inserts, then turn them back on. (But that leaves you vulnerable to screw-ups.)
I have a mysql database which have set of tables One table have a composite key as the primary key and and a single foreign key. Following are the table definitions.
CREATE TABLE IF NOT EXISTS `ohrm_emp_education` (
`emp_number` int(11) NOT NULL,
`education_id` int(11) NOT NULL,
`institute` varchar(100) DEFAULT NULL,
`major` varchar(100) DEFAULT NULL,
`year` decimal(4,0) DEFAULT NULL,
`score` varchar(25) DEFAULT NULL,
`start_date` date DEFAULT NULL,
`end_date` date DEFAULT NULL,
PRIMARY KEY (`emp_number`,`education_id`),
KEY `education_id` (`education_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
ALTER TABLE `ohrm_emp_education`
ADD CONSTRAINT `ohrm_emp_education_ibfk_1` FOREIGN KEY (`emp_number`) REFERENCES `hs_hr_employee` (`emp_number`) ON DELETE CASCADE,
ADD CONSTRAINT `ohrm_emp_education_ibfk_2` FOREIGN KEY (`education_id`) REFERENCES `ohrm_education` (`id`) ON DELETE CASCADE;
But now I need to add a new column to this existing table and make it as the primary key. I tried it with the following query.
ALTER TABLE ohrm_emp_education
ADD column id int not null AUTO_INCREMENT,
DROP PRIMARY KEY,
ADD primary key (id)
But it shows following error
#1025 - Error on rename of './test/#sql-4f6_19b' to './test/ohrm_emp_education' (errno: 150)
I tried with several answers which are found on the internet but couldn't solve it properly. Can someone help me on this. Thanks in advance.
Try to delete foreign keys first, something like this:
ALTER TABLE `ohrm_emp_education` DROP FOREIGN KEY `emp_number`;
ALTER TABLE `ohrm_emp_education` DROP FOREIGN KEY `education_id`;
And then alter table.
If you are using SQL Server Management Studio.
Then right click on the table and click design.
Then right click on the row which contains the composite key
and click on remove primary key
then add new column
and insert data into that column
and check that the column has no empty data.
Then again go to design view
and right click on the required column and click on Set as Primary Key
You're Done!!
You usually get this error if your tables use the InnoDB engine. In that case you would have to drop the foreign key, and then do the alter table and drop the column.
drop/disable foreign key constraint. Drop primary key, add new PK, enable/add fk.
I have the following tables:
specie (MyIsam)
image (InnoDB)
specie_map (InnoDB)
The specie_map table should map an image to a specie, and therefore has the following columns:
specie_id
image_id
Both are int 11, just like the id columns of the specie and image tables. I know I can't create a foreign key between specie_id and specie=>id, since the specie table is a MyIsam table. However, I would expect it to be possible to create a foreign key between image_id and image=>id.
I can create that foreign key and it will save it, however, the CASCADE action I have associated with it does not work. When I delete an image, it does not delete the specie_map entry that is associated with it. I would expect this to work, as this foreign key is between InnoDB tables. Both columns are indexed and of the same data type.
Is this a limitation of MySQL, or am I doing something else wrong?
Update: as requested hereby the table definitions. I have snipped unimportant columns:
-- ----------------------------
-- Table structure for `image`
-- ----------------------------
DROP TABLE IF EXISTS `image`;
CREATE TABLE `image` (
`id` int(11) NOT NULL auto_increment,
`guid` char(36) default NULL,
`title` varchar(255) NOT NULL,
`description` text,
`user_id` int(11) NOT NULL,
`item_id` int(11) default NULL,
`date_uploaded` timestamp NOT NULL default '0000-00-00 00:00:00',
`date_created` timestamp NOT NULL default '0000-00-00 00:00:00',
`date_modified` timestamp NOT NULL default '0000-00-00 00:00:00',
`status` enum('softdeleted','tobedeleted','active') default 'active',
PRIMARY KEY (`id`),
KEY `image_user` (`user_id`),
KEY `image_item` (`item_id`),
KEY `image_mod_by` (`moderated_by`),
CONSTRAINT `image_mod_by` FOREIGN KEY (`moderated_by`) REFERENCES `user` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `image_user` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='stores image data (not file data)';
-- ----------------------------
-- Table structure for `specie`
-- ----------------------------
DROP TABLE IF EXISTS `specie`;
CREATE TABLE `specie` (
`id` int(11) NOT NULL auto_increment,
`name` varchar(256) NOT NULL,
`commonname` varchar(256) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=22 DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC;
-- ----------------------------
-- Table structure for `specie_map`
-- ----------------------------
DROP TABLE IF EXISTS `specie_map`;
CREATE TABLE `specie_map` (
`id` int(11) NOT NULL auto_increment,
`image_id` int(11) NOT NULL,
`specie_id` int(11) NOT NULL,
`user_id` int(11) NOT NULL,
`karma` int(11) NOT NULL,
`date_created` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
PRIMARY KEY (`id`),
KEY `image_id` (`image_id`),
KEY `specie_id` (`specie_id`),
CONSTRAINT `specie_map_ibfk_1` FOREIGN KEY (`image_id`) REFERENCES `image` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Foreign keys works only with InnoDb in mysql. MyISAM doesn't support them (the statements are ignored).
And is there any reason why you mix multiple DB engines?
I think you should post the exact DDL statements you used when you attempted to create these tables and the foreign key. Foreign keys between innodb tables work fine, but there are still a few things to look out for:
0) Both tables must be InnoDB. This was already highlighted by the other posters and this is probably the immediate cause of your problem.
1) the data type of the referencing columns (those that make up the foreign key) and their respective referenced columns should be the same. For example, you can't create a foreign key constrain on an INT UNSIGNED column to a plain INT column.
2) if the foreign key is created as part of the table DDL, be sure to put the foreign key definition in the constraints section, that is, below all column definitions. For example:
CREATE TABLE parent (
id int unsigned PRIMARY KEY
);
CREATE TABLE child (
parent_id int unsigned
, foreign key (parent_id)
references parent (id)
);
will work but this:
CREATE TABLE child (
parent_id int unsigned
foreign key references parent (id)
);
won't. It will fail silently because MySQL's parser ignores these types of constraint definitions even before InnoDB gets to create the table (silly, but that's how it is)
3) There must be an index over all the referenced columns. Usually the referenced columns will together make up a primary key or a unique constraint anyway, but it is your job to define this before defining the foreign key.
Final word of advice: if you think your DDL is ok but you still get an error when you execute it, for example like this:
ERROR 1005 (HY000): Can't create table 'test.child' (errno: 150)
Warning (Code 150): Create table 'test/child' with foreign key constraint failed. There is no index in the referenced table where the referenced columns appear as the first columns.
Error (Code 1005): Can't create table 'test.child' (errno: 150)
Then these errors may still not reveal the true nature of the error (silly again, but that's how it is). To shed more light on it, run this command immediately after your attempt to create the foreign key:
SHOW ENGINE INNODB STATUS;
This will give you a bunch of status info, and one section there looks like this:
------------------------
LATEST FOREIGN KEY ERROR
------------------------
120122 11:38:28 Error in foreign key constraint of table test/child:
foreign key (parent_id) references parent (id) ):
Cannot find an index in the referenced table where the
referenced columns appear as the first columns, or column types
in the table and the referenced table do not match for constraint.
Note that the internal storage type of ENUM and SET changed in
tables created with >= InnoDB-4.1.12, and such columns in old tables
cannot be referenced by such columns in new tables.
See http://dev.mysql.com/doc/refman/5.5/en/innodb-foreign-key-constraints.html
for correct foreign key definition.
As you can see, this gives a bit more information and reveals the true problem, namely "column types in the table and the referenced table do not match for constraint"
So please, post your actual DDL, I'm sure there is a problem in there somewhere.
I am trying to design a database but I need some help with the relationships. Am i getting the table design right?
Here is the database idea..
User will submit a howto, each howto will have one or more steps associated with(a one to many). each step can have random pictures associated with(another one to many). so I am thinking of this:
CREATE TABLE `HowtoStepImage`
`id` int(10) unsigned NOT NULL auto_increment,
`user_id` int(10) unsigned NOT NULL,
`howto_id` varchar(25) NOT NULL,
`step_id` varchar(25) NOT NULL,
`img_id` int(10) unsigned NOT NULL,
PRIMARY KEY (`id`),
KEY `hsi_k_1` (`howto_id`),
CONSTRAINT `hsi_ibfk_1` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`),
CONSTRAINT `hsi_ibfk_2` FOREIGN KEY (`step_id`) REFERENCES `HowtoStep` (`step_id`),
CONSTRAINT `hsi_ibfk_3` FOREIGN KEY (`img_id`) REFERENCES `StepImage` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
table HowtoStep
step_id, title, content, created
primary key (step_id)
table StepImage
img_id, filename, created
CREATE TABLE `UserHowtoComment` (
`id` int(10) unsigned NOT NULL auto_increment,
`howto_id` varchar(25) NOT NULL,
`user_id` int(10) unsigned NOT NULL,
`comment` varchar(500) NOT NULL,
`created` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
PRIMARY KEY (`id`),
KEY `UserHowtoComment_ibfk_1` (`howto_id`),
KEY `UserHowtoComment_ibfk_2` (`user_id`),
CONSTRAINT `UserHowtoComment_ibfk_1` FOREIGN KEY (`howto_id`) REFERENCES `HowtoStepImage` (`howto_id`),
CONSTRAINT `UserHowtoComment_ibfk_2` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
however, I am getting error when creating the table, I am sure it is due to my database design. here is what mysql>SHOW ENGINE INNODB STATUS; shows:
091217 9:59:59 Error in foreign key constraint of table UserhowtoComment:
FOREIGN KEY (`howto_id`) REFERENCES `howtoStepImage` (`howto_id`),
CONSTRAINT `UserHowtoComment_ibfk_2` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8:
Cannot find an index in the referenced table where the
referenced columns appear as the first columns, or column types
in the table and the referenced table do not match for constraint.
Note that the internal storage type of ENUM and SET changed in
tables created with >= InnoDB-4.1.12, and such columns in old tables
cannot be referenced by such columns in new tables.
See http://dev.mysql.com/doc/refman/5.0/en/innodb-foreign-key-constraints.html
for correct foreign key definition.
the howto_id is a key(index) in UserHowtoComment though. I am not sure if that is the exact problem here..
Make 3 tables: one for HowTo, one for HowToStep, one for HowToStepImage.
Give each table a clearly defined key, e.g. a number or a string.
Then let the 'child' table refer to the key of the parent table.
Make sure that the columns have clear names as well.
TABLE HowTo
COLUMNS HowToId(key)
TABLE HowToStep
COLUMNS HowToStepId(key), HowToId
TABLE HowToStepImage
COLUMNS HowToStepImageId(key), HowToStepId
your query is really messy e.g. step_id varchar(25) needs to be an int.
why dont you just use a gui programm or maybe the good old phpMyAdmin, so you can learn the from the Querys they are creating, phpMyAdmin also has a advanced feature call "Designer" to create constraints.
If I read this correctly, your HowToComment id is a foreign key to HowtoStepImage. Does every comment have to have an image? Seems like a chicken and the egg issue. It seems, from your problem description, that an image links to a comment, not the other way around.
you're falling prey to the misleading terminology in MySQL. in the relational model, key is (necessarily) distinct. in the MySQL-speak, it's just an index. you need either PRIMARY KEY or UNIQUE KEY.
edit to add explicitly what is implied above: foreign keys must point to a key in the relational sense.