i'm trying to make an sql create table but I fail to make a foreign key.
My code :
Db::getInstance()->execute('
CREATE TABLE IF NOT EXISTS `'._DB_PREFIX_.'sondage`(
`id` int(6) NOT NULL AUTO_INCREMENT,
`question` varchar(60) NOT NULL,
PRIMARY KEY(`id`)) ENGINE='._MYSQL_ENGINE_.' default CHARSET=utf8')
|| !Db::getInstance()->execute('
CREATE TABLE IF NOT EXISTS `'._DB_PREFIX_.'sondage_reponse`(
`id` int(6) NOT NULL AUTO_INCREMENT,
`champ1` int(4) NOT NULL,
`champ2` int(4) NOT NULL,
`champ3` int(4) NOT NULL,
PRIMARY KEY(`id`)) ENGINE='._MYSQL_ENGINE_.' default CHARSET=utf8')
|| !Db::getInstance()->execute('
INSERT INTO '._DB_PREFIX_.'sondage_reponse (champ1,champ2,champ3)
VALUES (0,0,0)')
I want to make id from "sondage" foreign key in "sondage_reponse".I've tryed :
ALTER TABLE ps_sondage_reponse
ADD FOREIGN KEY fk_id_sdg(id)
REFERENCES sondage(id)')
But Prestashop can't add the foreign key.
Thx
i'd say to try this :
ALTER TABLE ps_sondage_reponse
ADD CONSTRAINT FK_id_sdg
FOREIGN KEY (id) REFERENCES sondage(id)
Related
I'm confused, because of this 3 tables, can i call a foreign key in another foreign key?
I got 3 tables, Component, PC, and Processor.
ALTER TABLE `component` (
`componentID` int(10) NOT NULL AUTO_INCREMENT,
`Name_component` varchar(100) DEFAULT NULL,
`Type` varchar(100) NOT NULL,
`processorIDFK` int(10) NOT NULL,
PRIMARY KEY (`componentID`),
UNIQUE KEY `Processor` (`processorId`),
CONSTRAINT processor_IDFK FOREIGN KEY (`processorIDFK`) REFERENCES processor(`processorID`)
);
ALTER TABLE `PC` (
`PCID` int(10) NOT NULL AUTO_INCREMENT,
`name_PC` varchar(100) DEFAULT NULL,
`componentIDFK` int(10) NOT NULL,
PRIMARY KEY (`PCID`),
UNIQUE KEY `component` (`componentId`),
CONSTRAINT component_IDFK FOREIGN KEY (`componentIDFK`) REFERENCES component(`componentId`)
);
CREATE TABLE `processor` (
`processorId` int(10) NOT NULL AUTO_INCREMENT,
`processor_Name` varchar(100) DEFAULT NULL,
PRIMARY KEY (`processorId`)
);
Can i call/use SELECT for processor_name in PC table? with this table relationship?
Yes, you can.
The thing you need to do is to join your tables.
SELECT processor_Name FROM PC t1
INNER JOIN component t2 ON t1.componentIDFK=t2.componentID
INNER JOIN processor t3 ON t3.processorId=t2.processorIDFK
I am trying to create foreign key in one of my table but i am getting this error can you help with this
CREATE TABLE IF NOT EXISTS `albums` (
`id` smallint(5) unsigned NOT NULL,
`url` mediumtext NOT NULL,
`year` mediumint(9) NOT NULL,
`album_name` varchar(150) NOT NULL,
`album_cover` text NOT NULL,
`tracks_id` text NOT NULL,
`category` tinyint(4) NOT NULL,
`reciter` tinyint(4) NOT NULL,
`keywords` varchar(300) NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
Foreign Key Table Structure
CREATE TABLE IF NOT EXISTS `album_likes` (
`album_id` int(5) NOT NULL,
`likes` int(11) NOT NULL,
`dislikes` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Now what i did to make this foreign key is that i went to the structure of this table in phpmyadmin and then add constraint name select the columns
Here is the query
ALTER TABLE `album_likes` ADD CONSTRAINT `album_like_fk` FOREIGN KEY (`album_id`) REFERENCES `mp3script`.`albums`(`id`) ON DELETE CASCADE ON UPDATE NO ACTION;
The output i got
1215 - Cannot add foreign key constraint
A foreign key requires an index on the column you are referencing, in this case albums.id.
Add the index:
CREATE INDEX ids_nn_1 on albums(id);
And you create foreign key should work
I have a table that I want to have an id that will auto increase itself but not be primary or unique.
Is this possible?
You should really create another table, in that case.
E.g.
CREATE TABLE `Calls` (
`Id` INT(10) AUTO_INCREMENT,
`From` VARCHAR(100) NOT NULL,
`To` VARCHAR(100) NOT NULL,
PRIMARY KEY (`Id`)
) ENGINE=INNODB;
CREATE TABLE `CallHistory` (
`Id` INT(15) AUTO_INCREMENT,
`CallId` INT(10) NOT NULL,
`Text` VARCHAR(255) NOT NULL,
PRIMARY KEY (`Id`),
KEY `CallHistory_Calls_idx` (`CallId`),
CONSTRAINT `CallHistory_Calls`
FOREIGN KEY (`CallId`)
REFERENCES `calls` (`Id`)
ON DELETE CASCADE
ON UPDATE CASCADE
) ENGINE=INNODB;
Here's a demo on SQLFiddle.
A benefit of this is that if you delete a row from Calls, the rows in CallHistory will also be deleted.
Running this query:
SELECT `Calls`.`Id`,
`Calls`.`From`,
`Calls`.`To`,
`CallHistory`.`Text`
FROM `Calls`, `CallHistory`
WHERE `Calls`.`Id` = `CallHistory`.`CallId`;
Gives results something like this:
This should work:
id int NOT NULL AUTO_INCREMENT
Anyway I don't see how it wouldn't stay unique unless you update existing values later
Yes, you need to set auto_increment constraint:
CREATE TABLE `test` (
`testID` int(11) NOT NULL, //primary key here
`testInc` int(11) NOT NULL AUTO_INCREMENT, //here is your non-primary auto increment column
PRIMARY KEY (`testID`),
KEY `testInc` (`testInc`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
and if you want this to be unique also then you may add unique constraint:
ALTER TABLE `test` ADD CONSTRAINT ux_unique_constraint UNIQUE `testInc`
I am creating three tables and when trying to tie the primary and foreign keys I am receiving the error message "Key column 'username' doesn't exist in table".
Could someone take a look at my code and tell me what I am doing wrong? I have tried dropping the database and revamped the tables a few times but I am still getting the same message. Here is my code, thank you in advance for any help!
create database testproject
use testproject
create table caller_info
(
caller_id int(11) unsigned auto_increment primary key not null,
first_name varchar(35) not null,
Last_name varchar(35) not null,
phone_number int(25) not null
);
create table caller_call_record
(
call_record_id int(11),
Call_Description varchar(50),
franchise_id int(10) not null,
email varchar(40) not null,
username varchar(25) primary key not null
);
create table caller_escalation
(
call_escalation_id int(11) unsigned auto_increment not null,
Second_Level varchar(5) not null,
caller_id int(11) not null,
PRIMARY KEY(call_escalation_id),
FOREIGN KEY(caller_id)
REFERENCES caller_info(caller_id),
FOREIGN KEY(username) REFERENCES caller_call_record(username)
);
As pointed out, your table caller_escalation needs a column called username in order to create the foreign key.
It sounds like once you've added that, you're now getting a Cannot add foreign key constraint error from MySQL. The first thing that comes to mind with this kind of error is that you're using the wrong engine for your tables. You are most likely using MyISAM which does not support foreign key references - in order to use these, you will need to change the engine on all of your tables to InnoDB.
try this:
create table caller_call_record
(
call_record_id int(11),
Call_Description varchar(50),
franchise_id int(10) not null,
email varchar(40) not null,
username varchar(25) not null,
PRIMARY KEY (username)
);
create table caller_escalation
(
call_escalation_id int(11) unsigned auto_increment not null,
Second_Level varchar(5) not null,
caller_id int(11) not null,
username varchar(25) not null,
PRIMARY KEY(call_escalation_id,username),
FOREIGN KEY(caller_id)
REFERENCES caller_info(caller_id),
FOREIGN KEY(username) REFERENCES caller_call_record
);
The table caller_escalation also needs a column username, which is not there
create table caller_escalation
(
call_escalation_id int(11) unsigned auto_increment not null,
Second_Level varchar(5) not null,
caller_id int(11) unsigned not null, ;; <--- added unsigned type here
PRIMARY KEY(call_escalation_id),
username varchar(25) not null, ;; <--- added field here
FOREIGN KEY(caller_id)
REFERENCES caller_info(caller_id),
FOREIGN KEY (username) REFERENCES caller_call_record (username)
);
Also ensure the column data types are the same in both tables. You have "caller_id int(11) unsigned" in caller_info and "caller_id int(11)" in caller_escalation. I added the unsigned specifier above to make it work.
this table is already work fine
create table posts (
id bigint(20) unsigned not null auto_increment,
title varchar(200) not null,
content text,
mdesc varchar(340),
pdate timestamp not null default current_timestamp,
lupdate timestamp not null default '0000-00-00 00:00:00',
perma varchar(120) not null,
cat_id smallint(5) unsigned not null,
user_id int(11) unsigned not null,
views int(11) unsigned not null default 0,
status tinyint(1) unsigned not null default 0,
primary key (id),
unique key (title,cat_id),
foreign key (cat_id) references category (id) on delete restrict on update cascade,
foreign key (user_id) references users (id) on delete cascade on update cascade
) engine=innodb default charset=utf8;
but i dont know why i cant query viewers table i dont know why
create table viewers (
id int(11) unsigned not null auto_increment,
post_id bigint(20) unsigned not null,
primary key (id),
foreign key (post_id) references posts (id) on delete cascade
) engine=innodb default charset=utf8;
please help :)
Please try removing fks
Most commonly it is because of different properties.
Check
if id of post table is having same properties as of this? (here bigint)
Other possibilities could be
it isn't innodb engine for other table.
Names of fks are not unique