Related
Is there a way to get a list of tables that have one-on-one relationship to a given table in SQLite3?
For example, here table ab has a one-on-one relationship with both table abc and abd. Is there a query or queries to return abc and abd for the given table name ab?
-- By default foreign key is diabled in SQLite3
PRAGMA foreign_keys = ON;
CREATE TABLE a (
aid INTEGER PRIMARY KEY
);
CREATE TABLE b (
bid INTEGER PRIMARY KEY
);
CREATE TABLE ab (
aid INTEGER,
bid INTEGER,
PRIMARY KEY (aid, bid)
FOREIGN KEY (aid) REFERENCES a(aid)
FOREIGN KEY (bid) REFERENCES b(bid)
);
-- tables 'ab' and 'abc' have a one-on-one relationship
CREATE TABLE abc (
aid INTEGER,
bid INTEGER,
name TEXT NOT NULL,
PRIMARY KEY (aid, bid) FOREIGN KEY (aid, bid) REFERENCES ab(aid, bid)
);
-- tables 'ab' and 'abd' have a one-on-one relationship
CREATE TABLE abd (
aid INTEGER,
bid INTEGER,
value INTEGER CHECK( value > 0 ),
PRIMARY KEY (aid, bid) FOREIGN KEY (aid, bid) REFERENCES ab(aid, bid)
);
CREATE TABLE w (
id INTEGER PRIMARY KEY
);
The following tedious precedure may get me the list of tables I want:
Get primary keys for table ab:
SELECT l.name FROM pragma_table_info('ab') as l WHERE l.pk > 0;
get foreign keys for other tables (this case is for table abd):
SELECT * from pragma_foreign_key_list('abd');
Do parsing to get what the list of tables of one-on-one relationships.
However, there must exist a more elegant way, I hope.
For SQL Server, there are sys.foreign_keys and referenced_object_id avaible (see post). Maybe there is something similar to that in SQLite?
Edit: adding two more tables for test
-- tables 'ab' and 'abe' have a one-on-one relationship
CREATE TABLE abe (
aid INTEGER,
bid INTEGER,
value INTEGER CHECK( value < 0 ),
PRIMARY KEY (aid, bid) FOREIGN KEY (aid, bid) REFERENCES ab
);
-- tables 'ab' and 'abf' have a one-on-one relationship
CREATE TABLE abf (
aidQ INTEGER,
bidQ INTEGER,
value INTEGER,
PRIMARY KEY (aidQ, bidQ) FOREIGN KEY (aidQ, bidQ) REFERENCES ab(aid, bid)
);
Edit: verify FK for table abe
sqlite> PRAGMA foreign_keys;
1
sqlite> .schema abe
CREATE TABLE abe (
aid INTEGER,
bid INTEGER,
value INTEGER CHECK( value < 0 ),
PRIMARY KEY (aid, bid) FOREIGN KEY (aid, bid) REFERENCES ab
);
sqlite> DELETE FROM abe;
sqlite> INSERT INTO abe (aid, bid, value) VALUES (2, 1, -21);
sqlite> INSERT INTO abe (aid, bid, value) VALUES (-2, 1, -21);
Error: FOREIGN KEY constraint failed
sqlite> SELECT * FROM ab;
1|1
1|2
2|1
Alternative
Although not a single query solution the following only requires submission/execution of a series of queries and is therefore platform independent.
It revolves around using two tables:-
a working copy of sqlite_master
a working table to store the the output of SELECT pragma_foreign_key_list(?)
Both tables are created via a CREATE-SELECT, although neither has any rows copied, so the tables are empty.
A trigger is applied to the working copy of sqlite_master to insert into the table that stores the result of SELECT pragma_foreign_key_list(table_name_from_insert);
The relevant rows are copied from sqlite_master via a SELECT INSERT and thus the triggering populates the store table.
The following is the testing code :-
DROP TABLE IF EXISTS fklist;
DROP TABLE IF EXISTS master_copy;
DROP TRIGGER IF EXISTS load_fklist;
/* Working version of foreign_key_list to store ALL results of SELECT pragma_foreign_key_list invocation */
CREATE TABLE IF NOT EXISTS fklist AS SELECT '' AS child,*
FROM pragma_foreign_key_list((SELECT name FROM sqlite_master WHERE type = 'not a type' LIMIT 1));
/* Working version of sqlite master */
CREATE TABLE IF NOT EXISTS master_copy AS SELECT * FROM sqlite_master WHERE type = 'not a type';
/* Add an after insert trigger for master copy to add to fklist */
CREATE TRIGGER IF NOT EXISTS load_fklist
AFTER INSERT ON master_copy
BEGIN
INSERT INTO fklist SELECT new.name,* FROM pragma_foreign_key_list(new.name);
END
;
/* Populate master_copy from sqlite_master (relevant rows)
and thus build the fklist
*/
INSERT INTO master_copy SELECT *
FROM sqlite_master
WHERE type = 'table'
AND instr(sql,' REFERENCES ') > 0
;
SELECT * FROM fklist;
DROP TABLE IF EXISTS fklist;
DROP TABLE IF EXISTS master_copy;
DROP TRIGGER IF EXISTS load_fklist;
Using a similar test base as per the previous answer the above results in :-
Is there a way to get a list of tables that have one-on-one relationship to a given table in SQLite3?
Not with certainty as coding a Foreign Key constraint does not define a relationship (rather it supports a relationship), that is relationships can exists without a FK constraint.
A Foreign Key constraint defines:-
a) a rule that enforces referential integrity
b) optionally maintains/alters referential integrity when the referred to column is changed (ON DELETE and ON UPDATE )
As such looking at the Foreign Key List only tells you where/if a FK constraint has been coded.
Saying that the following will get the tables with the constraint and the referenced tables.
More elegant is a matter of opinion, so it's up to you :-
WITH cte_part(name,reqd,rest) AS (
SELECT name,'',substr(sql,instr(sql,' REFERENCES ') + 12)||' REFERENCES '
FROM sqlite_master
WHERE sql LIKE '% REFERENCES %(%'
UNION ALL
SELECT
name,
substr(rest,0,instr(rest,' REFERENCES ')),
substr(rest,instr(rest,' REFERENCES ') + 12)
FROM cte_part
WHERE length(rest) > 12
)
SELECT DISTINCT
CASE
WHEN length(reqd) < 1 THEN name
ELSE
CASE substr(reqd,1,1)
WHEN '''' THEN substr(replace(reqd,substr(reqd,1,1),''),1,instr(reqd,'(')-3)
WHEN '[' THEN substr(replace(replace(reqd,'[',''),']',''),1,instr(reqd,'(')-3)
WHEN '`' THEN substr(replace(reqd,substr(reqd,1,1),''),1,instr(reqd,'(')-3)
ELSE substr(reqd,1,instr(reqd,'(')-1)
END
END AS tablename
FROM cte_part
;
As an example of it's use/results :-
screenshot from Navicat
Here's an adaptation of the above that includes, where appropriate, the child table that references the parent :-
WITH cte_part(name,reqd,rest) AS (
SELECT name,'',substr(sql,instr(sql,' REFERENCES ') + 12)||' REFERENCES '
FROM sqlite_master
WHERE sql LIKE '% REFERENCES %(%'
UNION ALL
SELECT
name,
substr(rest,0,instr(rest,' REFERENCES ')),
substr(rest,instr(rest,' REFERENCES ') + 12)
FROM cte_part
WHERE length(rest) > 12
)
SELECT DISTINCT
CASE
WHEN length(reqd) < 1 THEN name
ELSE
CASE substr(reqd,1,1)
WHEN '''' THEN substr(replace(reqd,substr(reqd,1,1),''),1,instr(reqd,'(')-3)
WHEN '[' THEN substr(replace(replace(reqd,'[',''),']',''),1,instr(reqd,'(')-3)
WHEN '`' THEN substr(replace(reqd,substr(reqd,1,1),''),1,instr(reqd,'(')-3)
ELSE substr(reqd,1,instr(reqd,'(')-1)
END
END AS tablename,
CASE WHEN length(reqd) < 1 THEN '' ELSE name END AS referrer
FROM cte_part
;
Example of the Result :-
the artists table is referenced by albums as the SQL used to create the albums table is CREATE TABLE 'albums'([AlbumId] INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL ,[Title] TEXT NOT NULL ,[ArtistId] INTEGER NOT NULL , FOREIGN KEY ([ArtistId]) REFERENCES 'artists'([ArtistId]))
i.e. FOREIGN KEY ([ArtistId]) REFERENCES 'artists'([ArtistId]))
the employees table is self-referencing as per CREATE TABLE 'employees'(.... REFERENCES 'employees'([EmployeeId]))
Additional re comment:-
(I am still trying to understand your code...)
The code is based upon selecting rows from sqlite_master where the row is for a table (type = 'table'), as opposed to an index, trigger or view and where the sql column contains the word REFERENCES with a space before and after and there is a following left parenthesis.
The last condition used to weed out the likes of CREATE TABLE oops (`REFERENCES` TEXT, `x REFERENCES Y`);
For each selected row 3 columns are output:-
name which is the name of the table as extracted from the name column of sqlite_master,
reqd is initially an empty string (i.e. initial)
rest the rest of sql that follows the referred to table name with suffixed with REFERENCES.
The UNION ALL adds rows that are built upon what is newly added to the CTE, i.e. the three columns are extracted as per :-
name is the name
reqd is the sql from the rest column up until the first REFERENCES term (i.e. the table and referenced column(s))
rest is the sql from after the REFERENCES term
As with any recursion the end needs to be detected, this is when the entire sql statement has been reduced to being less than 12 (i.e the length of " REFERENCES ", the term used for splitting the sql statement).
This is what is termed as a RECURSIVE CTE
Finally the resultant CTE is then queried. If the reqd field is empty then the tablename column is the name column otherwise (i.e. the reqd column contains data(part of the sql)) the table name is extracted (part up to left parenthesis if not enclosed (`,' or [ with ])) or extracted from between the enclosure.
The following is what the final query results in if all the CTE columns are included (some data has been truncated):-
As can clearly be seen the extracted sql progressively reduces
The answer is intended as in-principle and has not been extensively tested to consider all scenarios, it may well need tailoring.
I have prepared a huge list of sql statements (INSERT calls)s in a file which I run from sqlite3 terminal with
.read tmp/commands.sql
When I run the command one or more times in session #1 all goes well with no error and result as expected the ignore prevents against error messages for the duplicates).
Now if I quit sqlite3 with .quit then immediately come back and run the same command .read tmp/commands.sql I get for each sql call in my commands.sql an error message "Error: near line xxx: FOREIGN KEY constraint failed"
My database is made of two tables with a relation
a foreign key is defined in the second table to link to the fist one on its unique ID (FolderID)
in the beginning of the sql script, I added PRAGMA foreign_keys = true; to I thought allow relations
Can you please explain why this is happening in the second session?
Thanks
The first call in the commands.sql file will look like this
PRAGMA foreign_keys = true;
/*
------------------------------------------------------------------
adding data in Folders for '0003_Runs/HiSeq2500/190921_7001450_0495_AH5JJ7BCX3
------------------------------------------------------------------
*/
INSERT OR IGNORE INTO Folders
(
Creator,
CreatorVersion,
DBAddDate,
FolderPath,
FolderName,
FolderSize,
Protection,
DeviceModel,
StartDate,
DeviceID,
RunNr,
FlowCellID,
ProjectNR,
Status,
DeliveryDate,
Comment
)
VALUES (
"AddIlluminaFolders2",
" 1.0; 2020-09-11",
"1600864879",
"0003_Runs/HiSeq2500",
"190921_7001450_0495_AH5JJ7BCX3",
"183173644288",
"0",
"HiSeq2500",
"190921",
"7001450",
"0495",
"AH5JJ7BCX3",
"",
"done",
"",
""
);
/*
------------------------------------------------------------------
adding data in Actions for 0003_Runs/HiSeq2500/190921_7001450_0495_AH5JJ7BCX3
------------------------------------------------------------------
*/
INSERT OR IGNORE INTO Actions
(
FolderID,
Creator,
CreatorVersion,
ActionDate,
ActionName,
Comment
)
VALUES (
last_insert_rowid(),
"AddIlluminaFolders2",
" 1.0; 2020-09-11",
"1600864879",
"AddIlluminaFolders2",
""
);
-- ----------------------------------------------------------------
followed by many other blocks of the same kind until end of file with PRAGMA foreign_keys = true;
Here is my full table definition
/*
Database structure for NCDataMngr and BigData_viewer
Author: Stéphane Plaisance - VIB-Nucleomics Core
database version: 1.0 - 2020-09-11
File Encoding : utf-8
REM: edit below if you change the database schema
=> INSERT INTO "version" (vnum, vdate) VALUES ("1.0", "2020-09-11");
*/
PRAGMA foreign_keys = false;
-- ----------------------------
-- Table structure for Folders
-- ----------------------------
DROP TABLE IF EXISTS "Folders";
CREATE TABLE "Folders" (
"FolderID" INTEGER NOT NULL PRIMARY KEY,
"Creator" TEXT(255,0),
"CreatorVersion" TEXT(255,0),
"DBAddDate" TEXT(255,0),
"FolderPath" TEXT(255,0) NOT NULL,
"FolderName" TEXT(255,0) NOT NULL,
"FolderSize" INTEGER(20,0),
"Protection" INTEGER(1,0),
"DeviceModel" TEXT(255,0),
"StartDate" TEXT(255,0),
"DeviceID" TEXT(255,0),
"RunNr" TEXT(255,0),
"FlowCellID" TEXT(255,0),
"ProjectNR" TEXT(255,0),
"Status" TEXT(255,0),
"DeliveryDate" TEXT(255,0),
"Comment" TEXT(255,0)
);
INSERT INTO "main".sqlite_sequence (name, seq) VALUES ("Folders", '0');
-- ----------------------------
-- Table structure for Actions
-- ----------------------------
DROP TABLE IF EXISTS "Actions";
CREATE TABLE "Actions" (
"FolderID" INTEGER NOT NULL,
"ActionID" INTEGER NOT NULL PRIMARY KEY,
"Creator" TEXT(255,0),
"CreatorVersion" TEXT(255,0),
"ActionDate" TEXT,
"ActionName" TEXT(255,0),
"Comment" TEXT(255,0),
CONSTRAINT "Folders2Actions" FOREIGN KEY ("FolderID") REFERENCES "Folders" ("FolderID") ON DELETE CASCADE ON UPDATE CASCADE
);
INSERT INTO "main".sqlite_sequence (name, seq) VALUES ("Actions", '0');
-- ----------------------------
-- Table structure for version
-- ----------------------------
DROP TABLE IF EXISTS "version";
CREATE TABLE "version" (
"vnum" text,
"vdate" text
);
INSERT INTO "main".sqlite_sequence (name, seq) VALUES ("version", '0');
INSERT INTO "version" (vnum, vdate) VALUES ("1.1", "2020-09-23");
-- ----------------------------
-- View structure for ActionView
-- ----------------------------
DROP VIEW IF EXISTS "ActionView";
CREATE VIEW "ActionView" AS SELECT
Actions.*,
Folders.FolderName
FROM
Actions
INNER JOIN Folders ON Folders.FolderID = Actions.FolderID
ORDER BY
Actions.FolderID ASC,
Actions.ActionID ASC;
-- ----------------------------
-- View structure for FolderView
-- ----------------------------
DROP VIEW IF EXISTS "FolderView";
CREATE VIEW "FolderView" AS SELECT
Folders.*
FROM
Folders
ORDER BY
Folders.FolderID ASC;
-- ----------------------------
-- Indexes structure for table Folders
-- ----------------------------
CREATE UNIQUE INDEX "idx_Folders_FolderPath_FolderName" on Folders ( "FolderPath", "FolderName" );
-- ----------------------------
-- Indexes structure for table Actions
-- ----------------------------
CREATE INDEX "idx_Actions_FolderID" ON Actions ("FolderID" ASC);
CREATE UNIQUE INDEX "idx_Actions_FolderID_Creator" ON Actions ("FolderID" ASC, "Creator");
PRAGMA foreign_keys = true;
last_insert_rowid(). When commands.sql is run mutliple times in the same session, last_insert_rowid() has the value of the last row inserted. Which will never give a FOREIGN KEY failure. When a new session is invoked, no rows are inserted (because of the "dupes"), last_insert_rowid() has value 0, thus FOREIGN KEY violation on Actions insert.
I tried to re-engineer a database, that I use at work. The one at work is MS Access. At home, it's MariaDB. For convenience, I use MySQL Workbench.
When sending the complete SQL dump to the server, I get an error concerning some foreign key not being correctly formed. I guess, it is a minor mistake, but still I cannot find it.
My InnoDB status tells me this:
LATEST FOREIGN KEY ERROR
2018-10-03 00:18:29 409c7450 Error in foreign key constraint of table `mydb`.`IF`:
FOREIGN KEY (`belegid`)
REFERENCES `mydb`.`tblBelegPositionen` (`belegfID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_tblBelege_tblECKassenschnittPositionen10`
FOREIGN KEY (`belegid`)
REFERENCES `mydb`.`tblECKassenschnittPositionen` (`belegfID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB:
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/5.6/en/innodb-foreign-key-constraints.html
for correct foreign key definition.
Create table '`mydb`.`IF`' with foreign key constraint failed. There is no index in the referenced table where the referenced columns appear as the first columns near '
FOREIGN KEY (`belegid`)
REFERENCES `mydb`.`tblBelegPositionen` (`belegfID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_tblBelege_tblECKassenschnittPositionen10`
FOREIGN KEY (`belegid`)
REFERENCES `mydb`.`tblECKassenschnittPositionen` (`belegfID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB'.
The really weird thing is that I do not have any table named "IF"...
Can anyone make heads or tails of this for me? That would be very much appreciated.
-- Table `mydb`.`tblBelegPositionen`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `mydb`.`tblBelegPositionen` ;
SHOW WARNINGS;
CREATE TABLE IF NOT EXISTS `mydb`.`tblBelegPositionen` (
`belegposid` INT NOT NULL AUTO_INCREMENT,
`belegposBetrag` DOUBLE NOT NULL,
`zahlartfID` INT NOT NULL,
`belegfID` INT NOT NULL,
PRIMARY KEY (`belegposid`))
ENGINE = InnoDB;
SHOW WARNINGS;
-- Table `mydb`.`tblECKassenschnittPositionen`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `mydb`.`tblECKassenschnittPositionen` ;
SHOW WARNINGS;
CREATE TABLE IF NOT EXISTS `mydb`.`tblECKassenschnittPositionen` (
`ecposid` INT NOT NULL AUTO_INCREMENT,
`belegfID` INT NOT NULL,
`ecposBetrag` DOUBLE NOT NULL,
`kassenschnittfID` INT NOT NULL,
PRIMARY KEY (`ecposid`))
ENGINE = InnoDB;
SHOW WARNINGS;
-- Table `mydb`.`tblBelege`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `mydb`.`tblBelege` ;
SHOW WARNINGS;
CREATE TABLE IF NOT EXISTS `mydb`.`tblBelege` (
`belegid` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`belegKassierer` INT NOT NULL,
`belegDatum` DATETIME NOT NULL,
`kassefID` INT NOT NULL,
`belegSchicht` INT NULL,
`gvfID` INT NOT NULL,
`belegJahr` YEAR NULL,
`belegDruckErfolgt` TINYINT(1) NULL,
`belegDruckDatum` DATETIME NULL,
`belegPeriodenfremdeBuchung` TINYINT(1) NULL,
PRIMARY KEY (`belegid`, `gvfID`, `kassefID`),
CONSTRAINT `fk_tblBelege_tblBelegPositionen10`
FOREIGN KEY (`belegid`)
REFERENCES `mydb`.`tblBelegPositionen` (`belegfID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_tblBelege_tblECKassenschnittPositionen10`
FOREIGN KEY (`belegid`)
REFERENCES `mydb`.`tblECKassenschnittPositionen` (`belegfID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
SHOW WARNINGS;
Ok, so there are a couple of things to know here, as there were a couple of errors. You must check all the items that the error mentions, for correctness, to avoid trouble.
The cannot find an index in the referenced table portion of the error message means that the column/field specified in the REFERENCES clause must be indexed in the other table.
Then, the column type definition of the column specified in the FOREIGN KEY clause must match the column type of the column specified in the REFERENCES clause too, so even though the first item corrects part of the problem, there will still be an error related to another portion of the message: ...or column types in the table and the referenced table do not match.
So, to fix item 1, run these 2 queries:
ALTER TABLE `tblbelegpositionen` ADD INDEX(`belegfID`);
ALTER TABLE `tbleckassenschnittpositionen` ADD INDEX(`belegfID`);
Then to fix item 2, I had to change the first column of table tblBelege
from this:
`belegid` INT UNSIGNED NOT NULL AUTO_INCREMENT,
to this:
`belegid` INT NOT NULL,
...so that they matched the same type as the belegfID column as defined in the other tables. After those two changes, I was able to successfully run your CREATE TABLE `tblBelege` statement.
So, to recap:
Run your create table statements for tblbelegpositionen and
tbleckassenschnittpositionen.
Then run the 2 ALTER statements shown above for item 1.
Modify the first column of table tblBelege to match the column types as defined to belegfID in the other tables for item 2.
Then run your modified CREATE TABLE statement (with the item 2 change applied) to create the tblBelege table.
I'm a little confused about the same FOREIGN KEY referencing 2 different tables, but if it works for you, then ok. (not saying that it cannot be done, I've never used a foreign key that way) Perhaps you meant the opposite, to have a foreign key in the other 2 tables (1 in each table) that refer to tblBelege instead? If so, then you could add unsigned to the type definition for belegfID and it would work, and would not need the change that I mentioned with item 2.
Oh, and after you run the ALTER statements, you can view the table structure by running:
SHOW CREATE TABLE `tblbelegpositionen`;
SHOW CREATE TABLE `tbleckassenschnittpositionen`;
...to get the KEY definition that was added to include with your CREATE TABLE statements. Since they both create the same key, you really only need to run one of those statements and then add the KEY definition to both table statements.
According to the SQLite documentation / FAQ a column declared INTEGER PRIMARY KEY will automatically get a value of +1 the highest of the column if omitted.
Using SQLite version 3.22.0 2018-01-22 18:45:57
Creating a table as follows:
CREATE TABLE test (
demo_id INTEGER PRIMARY KEY NOT NULL,
ttt VARCHAR(40) NOT NULL,
basic VARCHAR(25) NOT NULL,
name VARCHAR(255) NOT NULL,
UNIQUE(ttt, basic) ON CONFLICT ROLLBACK
) WITHOUT ROWID;
Then inserting like this:
INSERT INTO test (ttt, basic, name) VALUES ('foo', 'bar', 'This is
a test');
gives:
Error: NOT NULL constraint failed: test.demo_id
sqlite>
When it is expected to create a record with a demo_id value of 1. Even if the table already contains values, it'll fail inserting the row without explicitly specifying the id with the same error.
What am I doing wrong?
The documentation says that you get autoincrementing values for the rowid. But you specified WITHOUT ROWID.
I've a Rate table with the following structre:
CREATE TABLE Rate (
id INTEGER PRIMARY KEY AUTOINCREMENT,
book_id INTEGER,
value INTEGER,
user_id INTEGER,
FOREIGN KEY(user_id) REFERENCES User(ID),
FOREIGN KEY(book_id) REFERENCES book(ID) ON DELETE RESTRICT
)
And a book table with the following structure:
DROP TABLE IF EXISTS Book;
CREATE TABLE Book (
id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT UNIQUE NOT NULL,
ISBN VARCHAR,
author_id INTEGER,
editor_id INTEGER,
translator_id INTEGER,
publisher_id INTEGER,
"type" VARCHAR,
language VARCHAR,
"date" VARCHAR,
format VARCHAR,
summary TEXT,
FOREIGN KEY(author_id) REFERENCES Author(ID) ON DELETE SET NULL ON UPDATE CASCADE,
FOREIGN KEY(editor_id) REFERENCES Editor(ID) ON DELETE SET NULL ON UPDATE CASCADE,
FOREIGN KEY(translator_id) REFERENCES Translator(ID) ON DELETE SET NULL ON UPDATE CASCADE,
FOREIGN KEY(publisher_id) REFERENCES Publisher(ID) ON DELETE SET NULL ON UPDATE CASCADE
);
So, if I have a Rate entry like this:
1 1 4 3(ID, BOOK_ID, VALUE, USER_ID)
I shouldn't be able to delete the Book with the ID 1, right?
This is exactly what happens when I try to delete the Book with ID 1 on SQLITE Manager. It gives me
FOREIGN KEY constraint failed
However, when I call my delete from the code, it totally ignores the restriction and deletes the book and there's no change in the Rate entry it is still:
1 1 4 3
And my delete method is like the following:
public void delete() {
try {
String query = "DELETE FROM book WHERE id = ? ";
PreparedStatement statement = db.prepareStatement(query);
statement.setInt(1, (Integer) this.id);
statement.executeUpdate();
statement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
When i run PRAGMA foreign_keys on SQLITE Manager it returns 1. So, I assume that the database is created correctly.
The documentation says:
... foreign key constraints ... must still be enabled by the application at runtime, using the PRAGMA foreign_keys command. For example:
PRAGMA foreign_keys = ON;
Foreign key constraints are disabled by default (for backwards compatibility), so must be enabled separately for each database connection.