I want to fill a column with a format using its ID.
My table:
CREATE TABLE "TEST"
(
"ID" INTEGER,
"Formatted_Column" TEXT,
PRIMARY KEY("ID" AUTOINCREMENT)
);
I want to do:
INSERT INTO TEST (Formatted_Column) VALUES ('U' + this_ID);
INSERT INTO TEST (Formatted_Column) VALUES ('U' + this_ID);
I want the output to be:
ID
Formatted_Column
1
U1
2
U2
What methods can help me?
Note: I tried to use last_insert_rowid()+1, but I think it's kind of spaghetti code (: .
My database currently SQLite, but I will change it to MySQL or SQL Server later.
I will use an online database with multi-users.
Thank you
If your version of SQLite is 3.31.0+ you can define Formatted_Column as a generated column: (VIRTUAL or STORED):
CREATE TABLE "TEST" (
"ID" INTEGER,
"Formatted_Column" TEXT GENERATED ALWAYS AS ('U' || ID) STORED,
PRIMARY KEY("ID" AUTOINCREMENT)
);
After you insert 2 rows:
INSERT INTO TEST (ID) VALUES (NULL), (NULL);
you will have:
ID
Formatted_Column
1
U1
2
U2
Related
This question already has answers here:
Insert a value from a table in another table as foreign key
(3 answers)
Closed 4 months ago.
Very new to SQL in general, working on creating 2 Tables, 1 for example representing appliances with a primary key, second representing a microwave for example with its FK referencing the primary tables PK.
I'm using SERIAL as the id for the primary table, but don't know how to update or insert into the second table using that specific generated value from the first.
I've created my tables using PSQL (Postgres15) like so:
CREATE TABLE Appliances (
id SERIAL NOT NULL,
field1 integer NOT NULL DEFAULT (0),
--
PRIMARY KEY (id),
UNIQUE(id)
);
CREATE TABLE Microwaves (
id integer NOT NULL,
field1 integer,
--
PRIMARY KEY (id),
FOREIGN KEY (id) REFERENCES Appliances(id)
);
Inserting my first row into the Appliance table:
INSERT INTO Appliances(field1) VALUES(1);
SELECT * FROM Appliances;
Yields:
And a query I found somewhere pulls the current increment of the SERIAL:
SELECT currval(pg_get_serial_sequence('Appliances', 'id'));
Yields:
I'm struggling to determine how to format the INSERT statement, have tried several variations around the below input:
INSERT INTO Microwaves VALUES(SELECT currval(pg_get_serial_sequence('Appliances', 'id'), 1));
Yields:
Appreciate feedback on solving the problem as represented, or a better way to tackle this in general.
Okay looks like I stumbled on at least one solution that works in my case as taken from https://stackoverflow.com/a/50004699/3564760
DO $$
DECLARE appliance_id integer;
BEGIN
INSERT INTO Appliances(field1) VALUES('appliance2') RETURNING id INTO appliance_id;
INSERT INTO Microwaves(id, field2) VALUES(appliance_id, 100);
END $$;
Still open to other answers if this isn't ideal.
I want to UPDATE or INSERT a column in PostgreSQL instead of doing INSERT or UPDATE using INSERT ... ON CONFLICT ... because there will be more updates than more inserts and also I have an auto incrementing id column that's defined using SERIAL so it increments the id column everytime it tries to INSERT or UPDATE and that's not what I want, I want the id column to increase only if it's an INSERT so that all ids would be in an order instead
The table is created like this
CREATE TABLE IF NOT EXISTS table_name (
id SERIAL PRIMARY KEY,
user_id varchar(30) NOT NULL,
item_name varchar(50) NOT NULL,
code_uses bigint NOT NULL,
UNIQUE(user_id, item_name)
)
And the query I used was
INSERT INTO table_name
VALUES (DEFAULT, 'some_random_id', 'some_random_name', 1)
ON CONFLICT (user_id, item_name)
DO UPDATE SET code_uses = table_name.code_uses + 1;
Thanks :)
Upserts in PostgreSQL do exactly what you described.
Consider this table and records
CREATE TABLE t (id SERIAL PRIMARY KEY, txt TEXT);
INSERT INTO t (txt) VALUES ('foo'),('bar');
SELECT * FROM t ORDER BY id;
id | txt
----+-----
1 | foo
2 | bar
(2 Zeilen)
Using upserts the id will only increment if a new record is inserted
INSERT INTO t VALUES (1,'foo updated'),(3,'new record')
ON CONFLICT (id) DO UPDATE SET txt = EXCLUDED.txt;
SELECT * FROM t ORDER BY id;
id | txt
----+-------------
1 | foo updated
2 | bar
3 | new record
(3 Zeilen)
EDIT (see coments): this is the expected behaviour of a serial column, since they're nothing but a fancy way to use sequences. Long story short: using upserts the gaps will be inevitable. If you're worried the value might become too big, use bigserial instead and let PostgreSQL do its job.
Related thread: serial in postgres is being increased even though I added on conflict do nothing
I have a table with columns Form, Appraiser, date and Level
A form can never have same appraisers, and a form can never have same Levels.
I tried to make primary key(Form,appraiser) and primary key(Form,level) but it says that form has multiple primary keys
If i put primary key(form,appraiser,level) people can just insert the same form and appraiser twice but just with a different level and that violates my rules.
|Form|Appraiser|Level|
1 A 1
1 B 2
1 C 3
2 A 1
2 B 2
2 C 3
I believe you could use :-
CREATE TABLE IF NOT EXISTS mytable (form INTEGER, appraiser TEXT, level INTEGER, UNIQUE(form,appraiser), UNIQUE(form,level));
e.g. Using the following
DROP TABLE IF EXISTS mytable;
CREATE TABLE IF NOT EXISTS mytable (form INTEGER, appraiser TEXT, level INTEGER, UNIQUE(form,appraiser), UNIQUE(form,level));
INSERT INTO mytable VALUES
(1,'A',1),(1,'B',2),(1,'C',3),
(2,'A',1),(2,'B',2),(2,'C',3)
;
INSERT OR IGNORE INTO mytable VALUES (1,'A',4);
INSERT OR IGNORE INTO mytable values (1,'Z',1);
The results are :-
INSERT INTO mytable VALUES
(1,'A',1),(1,'B',2),(1,'C',3),
(2,'A',1),(2,'B',2),(2,'C',3)
> Affected rows: 6
> Time: 0.083s
all added
but
INSERT OR IGNORE INTO mytable VALUES (1,'A',4)
> Affected rows: 0
> Time: 0s
not added as A has already apprasied form 1.
and also
INSERT OR IGNORE INTO mytable values (1,'Z',1)
> Affected rows: 0
> Time: 0s
not added as for 1 has already been appraised at level 1
We can try using two junction tables here:
CREATE TABLE form_appraiser (
form_id INTEGER NOT NULL,
appraiser_id INTEGER NOT NULL,
PRIMARY KEY (form_id, appraiser_id)
);
CREATE TABLE form_level (
form_id INTEGER NOT NULL,
level_id INTEGER NOT NULL,
PRIMARY KEY (form_id, level_id)
);
Each of these two tables would ensure that a given form can only be associated with a single appraiser or level.
Then, maintain a third table forms containing one record for each unique form. If you have the additional requirement that a given form can only have one appraiser or level, then add a unique constraint on the form, on one/both of the junction tables.
You can try add the unique constraint as a column identifier.
like
appraiser VARCHAR(50) UNIQUE,
form VARCHAR(50) UNIQUE,
level VARCHAR(50) UNIQUE,
In this case non of the values repeats. If you want a combination of values not to repeat you can use
UNIQUE(form, level)
This means you cannot have a form of the same level repeating.
I am creating a sql file which has uuids as primary key. Here is how my create table definition looks like using pgcrypto extension
CREATE EXTENSION pgcrypto;
CREATE TABLE snw.contacts(
id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
name TEXT,
email TEXT
);
Now I add a record in this table using
INSERT INTO snw.contacts (name,email) VALUES('Dr Nic Williams','drnic');
postgres=# select * from snw.contacts;
id | name | email
--------------------------------------+-----------------+-------
7c627ee0-ac94-40ee-b39d-071299a55c13 | Dr Nic Williams | drnic
Now going ahead in the same file I want to insert a row in one of tables which looks like
CREATE TABLE snw.address(
id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
street TEXT
contact UUID
);
where contact UUID refers to ID in snw.contacts table. How can I fetch the uuid which was generated in the first insert and use it in another insert in the snw.address table?Something like:
INSERT INTO snw.address(street,contact) values('ABC', (select id from snw.contacts where email='drnic'));
I can use where clause I am using this script for generating some test data and so I know what the email would be for fetching the id.
Use a data modifying CTE:
with new_contact as (
INSERT INTO snw.contacts (name,email)
VALUES('Dr Nic Williams','drnic')
returning id
)
INSERT INTO snw.address(street,contact)
select 'ABC', id
from new_contact;
When I try and run the following command in SQLPlus:
CREATE TABLE Hotel
(hotelNo NUMBER(4) NOT NULL AUTO_INCREMENT,
hotelName VARCHAR(20) NOT NULL,
city VARCHAR(50) NOT NULL,
CONSTRAINT hotelNo_pk PRIMARY KEY (hotelNo));
I get the following error:
(hotelNo NUMBER(4) NOT NULL AUTO_INCREMENT,
*
ERROR at line 2:
ORA-00907: missing right parenthesis
What am I doing wrong?
Many will gripe about this not being a standard feature in Oracle, but when it’s as easy as two more commands after your CREATE TABLE command I can’t see any good reason to use fancy SQL on every insert.
First let’s create a simple table to play with.
SQL> CREATE TABLE test
(id NUMBER PRIMARY KEY,
name VARCHAR2(30));
Table created.
Now we’ll assume we want ID to be an auto increment field. First we need a sequence to grab values from.
SQL> CREATE SEQUENCE test_sequence
START WITH 1
INCREMENT BY 1;
Sequence created.
Now we can use that sequence in a BEFORE INSERT trigger on the table.
CREATE OR REPLACE TRIGGER test_trigger
BEFORE INSERT
ON test
REFERENCING NEW AS NEW
FOR EACH ROW
BEGIN
SELECT test_sequence.nextval INTO :NEW.ID FROM dual;
END;
/
SQL> INSERT INTO test (name) VALUES ('Jon');
1 row created.
SQL> INSERT INTO test (name) VALUES (’Bork’);
1 row created.
SQL> INSERT INTO test (name) VALUES (’Matt’);
1 row created.
SQL> SELECT * FROM test;
ID NAME
———- ——————————
1 Jon
2 Bork
3 Matt
Oracle has no auto_increment, you need to use sequences.
Or - starting with Oracle 12.1 - you can simply have:
CREATE TABLE employee
(
id NUMBER GENERATED by default on null as IDENTITY
....
)