I have a table Details in which _id is the primary key by default. Now while inserting i have to make multiple inserts to different tables. for each record I have to insert one row in Details table and one record in Notifications table this happens one after the other for each record.
Now I am assigning a foreign key to the second table that is Notifications, this is the primary key of details table(Which is auto increment integer) is this the right approach? I wonder how do I extract this primary key of details table as soon as insertion in Details table is made and then supply this _id as the foreign key to my next query which will add row in the notification table.
The second approach I think of would be to assign a different primary key in Details (Which I will supply to the query explicitly), keep a record of this key and use it as a foreign key in Notifications table.
SELECT last_insert_rowid()
will allow you to pick up the _id used in any previous insertion.
Just make sure this is executed after a Details table insert.
Related
Is there a smart way of getting the primary key that is auto incremented rather than rowID while inserting in the database, basically i don't want to write a new query to get the primary key of the last entry, is there any way to get the primary key using its rowID.
Thanks in advance.
Option 1 : If you use The Android SQLite DB class methods, they return the last inserted id.
Option 2 : SELECT last_insert_rowid();
Refer to question
I have a database in which i have created one table with name "SectionDetails".
In this table i have set "id" as a primary key with AUTOINCREMENT property.And i am inserting my data into this table.
However, i came to the scenario where i need to check if record i am inserting is already present or not(if record is present then replace it with same values or skip it,And if record is not present then insert new one ).
But when i tried to insert record with same column values, it increases the primary key and insert the same row again instead of replacing.
So, my question is-
Does sqlite "insert or replace" works with AUTOINCREMENT primary key?
I am using following query:
insert or replace into SectionDetails(Name,Month,Title,Url)values('Deepak',"August","None","www.dd619.com")
here column "id" is not appearing because its a primary key with AUTOINCREMENT property.
You will need to add some unique constraints to your other columns to make this work and even then you will have your IDs change.
insert or replace is really an insert with on conflict replace conflict resolution strategy. That is, when the insert would violate some constraint, all conflicting rows are first deleted and the insert takes place only then. The autoincrement mechanism will then generate a new ID value for you.
For more information: http://www.sqlite.org/lang_conflict.html
Short answer: no it does not.
The "insert or replace" only works well when you also specify the primary key. With the autoincrement in a setup that you describe, this cannot work.
Probably the quickest way to do that is by creating a custom insert/update method for your use case.
i have two tables DISCIPLINE and SUBJECT.
DISCIPLINE table has _DISCIPLINE_ID as a primary key and a DISCIPLINE_Name column.
SUBJECT table has _SUBJECT_ID as a primary key SUBJECT_Name and DISCIPLINE as a Forign key.
i want to select Subject from SUBJECT table Who has the same _DISCIPLINE_ID in the DISCIPLINE table.
here is my query:
SELECT DISCIPLINE._DISCIPLINE_ID,
SUBJECT.SUBJECT_Name
FROM DISCIPLINE,
SUBJECT
WHERE SUBJECT.DISCIPLINE = DISCIPLINE._DISCIPLINE_ID
it gives me data but it selects all the Subjects and DISCIPLINE.
i think it is how your from clause is built, have you tried inner join instead of a comma seperating the table selections?
i am getting information from user in sqlite database.
But when i insert same record which is already in database it is added again.
how i can stop duplication of record in sqlite. I am developing this in android.
I am using mobile number as primary key. still it add that record in database.
Please suggest me appropriate solutions.
Thanks in advanced.
Be aware of the limitations of REPLACE or INSERT OR REPLACE as these will overwrite any custom data your app user has added to these rows in the database - it is not as advanced as UPSERT in other SQL databases.
As mentioned in a previous post you really need to identify what the primary key could be and use this information to either update old data or to remove an old row before inserting the fresh one.
If this is not possible then you could always DELETE FROM my_table or DROP my_table before running the insertions so that there will be no duplicates. This will (for better or worse) also make sure that data that is missing from new imports is not left lying around in your app.
make sure you have set your phone number as Primary Key at the time you created the table.
for example:
String query = "CREATE TABLE IF NOT EXISTS PhoneBook ("+
"TelNum VARCHAR(100) PRIMARY KEY NOT NULL,"+
"Address TEXT);";
db.execSQL(query);
and in case you want to enforce foreign keys defined in your table then call the following method before doing anything in your database
db.execSQL("PRAGMA foreign_keys = ON;"); //enforcing FK
Use REPLACE INTO keyword:
REPLACE INTO my_table (pk_id, col1) VALUES (5, '123');
This automatically identifies the primary key and finds a matching row to update, inserting a new one if none is found.
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