Develop Reference

SQLite - integer PRIMARY INDEX constraint failing?

In my Android app, I create a FULLTEXT table like this:
CREATE VIRTUAL TABLE products USING fts3 (
_id integer PRIMARY KEY,
product_name text NOT NULL,
...
)
And I add this index:
CREATE INDEX product_name_index ON products (product_name)
The app populates the table with various products, each with a unique _id value.
However, when I then try to insert an already-existing product ID (using an _id value that is already in the table, but with a different product_name value) like this:
long rowId = db.insertOrThrow("products", null, contentValues);
a new row is added to the table (with a brand new rowId value returned)!
I expected the insertOrThrow command to fail, so where am I going wrong? Is it something to do with the fact that it's a FULLTEXT table or could the index I specified on the product_name column be messing things up somehow?
I read this section about INTEGER PRIMARY KEY, but unfortunately I'm none the wiser.
Update
When I try to perform the same operation on a standard (non-FULLTEXT) table, then the insertOrThrow command results in the expected SQLiteConstraintException.

I think the issue might be that an FTS table has the concept of a docid and a rowid column and specifying null for the docid results in that being given a value.
as per :-
There is one other subtle difference between "docid" and the normal
SQLite aliases for the rowid column.
Normally, if an INSERT or UPDATE
statement assigns discrete values to two or more aliases of the rowid
column, SQLite writes the rightmost of such values specified in the
INSERT or UPDATE statement to the database.
However, assigning a
non-NULL value to both the "docid" and one or more of the SQLite rowid
aliases when inserting or updating an FTS table is considered an
error. See below for an example.
1.3. Populating FTS Tables

How to set a 'DEFAULT' field when using fts3 Sqlite table?

I'm trying to set a default field in my table to current time. When I use a fts3 virtual table, inserting a row doesn't fill the default field to what it should be. Instead, it inserts null.
If I create the same table as normal table, the exact same query works and the field is populated.
Here are the 2 different table structures I'm using:
Normal table that default value does work
CREATE TABLE Emlak_test2 (_id INTEGER PRIMARY KEY,emlak_id TEXT,created_at TEXT DEFAULT (datetime('now', 'localtime')),emlak_sellorrent TEXT,emlak_cat TEXT,emlak_altcat TEXT,emlak_desc TEXT,emlak_living_rooms INTEGER,emlak_rooms INTEGER,emlak_sellprice INTEGER,emlak_temp TEXT,emlak_city TEXT,emlak_state TEXT,emlak_address TEXT,img_p1 TEXT,img_p2 TEXT,img_p3 TEXT,img_p4 TEXT,img_p5 TEXT,musteri_id TEXT);
FTS3 table that the default value does not work
CREATE VIRTUAL TABLE Emlak_test USING fts3 (_id INTEGER PRIMARY KEY,emlak_id TEXT,created_at TEXT DEFAULT (datetime('now', 'localtime')),emlak_sellorrent TEXT,emlak_cat TEXT,emlak_altcat TEXT,emlak_desc TEXT,emlak_living_rooms INTEGER,emlak_rooms INTEGER,emlak_sellprice INTEGER,emlak_temp TEXT,emlak_city TEXT,emlak_state TEXT,emlak_address TEXT,img_p1 TEXT,img_p2 TEXT,img_p3 TEXT,img_p4 TEXT,img_p5 TEXT,musteri_id TEXT);
Now, if I use this query;
insert into table_name default values;
on the first table, I can see that created_at field is populated. On the second table, the field is empty.
I hope you can help me with this.
Thank you!

The documentation says:
If column names are explicitly provided for the FTS table as part of the CREATE VIRTUAL TABLE statement, then a datatype name may be optionally specified for each column. This is pure syntactic sugar, the supplied typenames are not used by FTS or the SQLite core for any purpose. The same applies to any constraints specified along with an FTS column name – they are parsed but not used or recorded by the system in any way.
So it is not possible to have default values.
And,
it is not possible to create indices or triggers attached to FTS tables.
So it is not possible to work around this.

SQLite prevents duplicate column names in my VIEW

I am creating a SQLite VIEW that is the result of multiple joined tables. All my tables have an _id column as required by Android. The result has multiple columns with the same _id name, but SQLite adds ":1" and ":2" to the duplicate names so they are no longer duplicates.
If you run the below SQL you can see the resulting view has interesting column names:
CREATE TABLE things ("_id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL UNIQUE , "name" TEXT NOT NULL);
CREATE TABLE thing_colors ("_id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL UNIQUE , "thing_id" INTEGER NOT NULL , "color" TEXT NOT NULL);
INSERT INTO things VALUES ("1","car");
INSERT INTO things VALUES ("2","horse");
INSERT INTO things VALUES ("3","lamp");
INSERT INTO thing_colors VALUES ("1","1","blue");
INSERT INTO thing_colors VALUES ("2","1","red");
INSERT INTO thing_colors VALUES ("3","2","brown");
INSERT INTO thing_colors VALUES ("4","3","silver");
INSERT INTO thing_colors VALUES ("5","3","gold");
CREATE VIEW things_and_colors AS SELECT * FROM things JOIN thing_colors ON things._id=thing_colors.thing_id;
SELECT * FROM things_and_colors;
I find these renamed column names useful but is this normal SQL behavior and is it fine for me to rely on it?
But of course this is just an example, in real life I am joining three tables and the result has about 70 columns in it, of which 3 are named _id.

Don't select star, select the columns individually and assign an alias as needed.

No, you can't depend on the view renaming your columns to avoid conflicts. I don't have a copy of the standard handy so I can't quote chapter and verse but I know that PostgreSQL will say this:
ERROR: column "_id" specified more than once
and MySQL will say this:
ERROR 1060 (42S21): Duplicate column name '_id'
Those are the only databases I have handy at the moment.

Automatically Create Insert Statements to Fill Junction Table in a Pre-Created DB

For a simple android app I'm creating as a teaching tool for myself (for using relational dbs/SQL among other things - pardon the simplicity of the question if you will). I'm pre-creating a sqlite db to ship with the application. I'm doing this based on the following SO question.
I've got two tables with a many to many relationship and a junction table to define those relationships as follows:
CREATE TABLE Names (_id INTEGER PRIMARY KEY,
name TEXT
);
CREATE TABLE Categories (_id INTEGER PRIMARY KEY,
category TEXT
);
CREATE TABLE Name_Category (name_id INTEGER,
category_id INTEGER,
PRIMARY KEY (name_id, category_id),
foreign key (name_id) references Names(_id),
foreign key (category_id) references Categories(_id)
);
I've got sets of insert statements to fill the Names and Categories tables. I'm now faced with the task of filling the junction table. I'm sure that I could create the insert statements by hand by looking up the ids of the names and categories that I want to match, but that seems a bit silly.
In order to automatically create the insert statements for the junction table, I imagine that I could create a script based on a set of name and category pairs that will search for the appropriate ids and dump an insert statement. (I came up with this as I was asking the question and will research it. Don't you love it when that happens?)
Does anybody have any suggestions for ways to do this?
EDIT I added the foreign keys because, as pointed out below, they'll help maintain integrity between the tables.
EDIT #2 To solve this, I created a simple Perl script that would take a text file with name - category pairs and dump them out into another file with the appropriate SQL statements.
The name - category text file has a format as follows:
'Name' 'Category'
The Perl script looks like this:
use strict;
use warnings;
open (my $name_category_pair_file, "<", "name_category.txt") or die "Can't open name_category.txt: $!";
open (my $output_sql_file, ">", "load_name_category_junction_table.sqlite") or die "Can't open load_name_category_junction_table.sqlite: $!";
while (<$name_category_pair_file>) {
if (/('[a-zA-Z ]*') ('[a-zA-Z ]*')/) {
my $sql_statement = "INSERT INTO Name_Category VALUES (
(SELECT _id FROM Names WHERE name = $1),
(SELECT _id FROM Categories WHERE category = $2))\;\n\n";
print $output_sql_file $sql_statement;
}
}
close $name_category_pair_file or die "$name_category_pair_file: $!";
close $output_sql_file or die "$output_sql_file: $!";

You can use this insert in your script or code (replacing the strings or using ?):
insert into Name_Category values(
(select _id from Categories where category='CAT1'),
(select _id from Names where name='NAME1'));
Also, you can alter the Name_Category table to constraint on the values that can be inserted and/or deleted:
CREATE TABLE Name_Category ( name_id INTEGER NOT NULL,
category_id INTEGER NOT NULL,
PRIMARY KEY (name_id, category_id),
foreign key (name_id) references Names(_id),
foreign key (category_id) references Categories(_id));

create two main tables first and then create a junction table in which primary key of both main tables will be available as foreign key.. Primary key of junction table will be union
of primary key of first and second main table.
Create trigger now to automatically insert into junction table...
Also don't forget to create table with cascade deletion and cascade updatation so that any value updated or deleted in main tables will be automatically reflected in junction table

Problem with inserting into android sqlite3 table that has composite primary key

I have a table with a composite primary key and I am having trouble inserting. The code used to create the table is:
CREATE TABLE ClassEvent (
EventName varchar(10) NOT NULL,
CourseId varchar(10) NOT NULL,
EventType varchar(20),
EventWeight number(3),
DueDate DATE NOT NULL,
FOREIGN KEY (CourseId) REFERENCES Courses(CourseId),
PRIMARY KEY (CourseId, EventName));
The problem I am having is when I want to insert records that have values that may not be unique for the columns CourseId or EventName, but are a unique combination of the 2.
for example, if I try to run the following 2 inserts:
INSERT INTO ClassEvent VALUES('Assignment 1','60-415','Assignment',10,'12/10/2010');
INSERT INTO ClassEvent VALUES('Project 1','60-415','Project',15,'5/12/2010');
I get the following error:
Error: columns CourseId, EventName are not unique.
and the second insert does not make it into the DB. Why does this error out? I thought that a composite primary key requires that the combination of both values are unique. In my above inserts, the values for the EventName column are different even though the values for CourseId are the same. Shouldn't this be seen as 2 unique combinations and thus 2 different primary keys?
My table needs to be able to hold several different events for each CourseId, but each Event must be unique for each Course. I need to be able to insert values into the table like:
EventName CourseId
Assignment 1 60-415
Project 1 60-415
Assignment2 60-415
Project 2 60-415
Assignment 1 60-367
Project 1 60-367
and so on. Can anyone tell me how I can get this to work? Why are these composite PK's not being seen as unique entries? Any help would be much appreciated.
Here is the java function I am using for the insert:
public void addNewClassEvent(ContentValues values) {
SQLiteDatabase db = openConnection();
db.insert("ClassEvent", null, values);
db.close();
}
Could this be causing the problem?

You can have a composite primary key in SQLite, but you
have to create the key when you create the table:
CREATE TABLE example1(
field1 FLOAT,
field2 TEXT,
PRIMARY KEY(field1, field2)
);
You cannot create the primary key after the fact using ALTER TABLE.
On the other hand, you can create a UNIQUE INDEX after the fact
which has essentially the same effect as a PRIMARY KEY:
CREATE UNIQUE INDEX pk_index ON "table1"("field1","field2");
I am not sure how you have created, the tables, and if you have added the primary index later, but grab the database to your desktop, and check out how works in a desktop environment.

You can't make combinations like that, but you don't need them. What is stopping you from just having a truly id column ?