I have two table with one to one relation and I want to insert two rows to the tables with the same auto increment id. Is it possible?
create table first
(
id bigint primary key,
value varchar(100) not null
);
create table second
(
id bigint references first (id),
sign boolean
);
insert into first(id, value)
values (-- autoincremented, 'some_value');
insert into second(id, sign)
values (-- the same autoincremented, true);
Your id column must be defined as an "auto increment" one before you can use that:
create table first
(
id bigint generated always as identity primary key,
value varchar(100) not null
);
Then you can use lastval() to get the last generated id:
insert into first(id, value)
values (default, 'some_value');
insert into second(id, sign)
values (lastval(), true);
Or if you want to be explicit:
insert into first(id, value)
values (default, 'some_value');
insert into second(id, sign)
values (currval(pg_get_serial_sequence('first','id')), true);
One option uses a cte with the returning clause:
with i as (
insert into first(value) values('some_value')
returning id
)
insert into second(id, sign)
select i.id, true from i
This performs the two inserts at once; the id of the first insert is auto-generated, and then used in the second insert.
For this to work, you need the id of the first table to be defined as serial.
Related
So I've been going through SQL migrations to insert data in a SEQUENTIAL manner specifically from parent to child.
I've inserted data in the parent table. Now I've to store the primary key value of that
specific row (WHERE condition is defined in query for reference " where description = '1234'") in a variable.
And while inserting data to the child table I've to use that primary key value stored in a variable in place of a foreign key column("country_code_id") of the child table.
I'm using Postgresql
CREATE TABLE Countries
(
id SERIAL,
description VARCHAR(100),
CONSTRAINT coutry_pkey PRIMARY KEY (id)
);
CREATE TABLE Cities
(
country_code_id int ,
city_id int,
description VARCHAR(100),
CONSTRAINT cities_pkey PRIMARY KEY (city_id),
CONSTRAINT fk_cities_countries FOREIGN KEY (country_code_id) REFERENCES Countries (id)
);
INSERT INTO COUNTRIES (description) VALUES('asdf');
#countrid = SELECT id FROM COUNTRIES WHERE description = 'asdf';
INSERT INTO cities VALUES (countrid, 1 , 'abc');
SQL does not have variables. The normal way to do this is to use INSERT ... RETURNING:
INSERT INTO countries (description) VALUES ('1234')
RETURNING id;
This will return the automatically generated primary key. You store that in a variable on the client side and run a second statement:
INSERT INTO cities (country_code_id, city_id, description)
VALUES (4711, 1, 'abc');
where 4711 is the value returned from the first statement. To avoid hard-coding the value, you can use a prepared statement, which also will boost performance.
An alternative, more complicated, solution is to run both statements in a single statement using a common table expression:
WITH country_ids AS (
INSERT INTO countries (description) VALUES ('1234')
RETURNING id
INSERT INTO (country_code_id, city_id, description)
SELECT id, 1, 'abc'
FROM country_ids;
I'm running the following SQLite workaround to add a primary key to a table that did not have one. I am getting a datatype mismatch on
INSERT INTO cities
SELECT id, name FROM old_cities;
However, the fields have exactly the same type. Is it possible that his happens due to running the queries from DbBrowser for SQLite?
CREATE table cities (
id INTEGER NOT NULL,
name TEXT NOT NULL
);
INSERT INTO cities (id, name)
VALUES ('pan', 'doul');
END TRANSACTION;
PRAGMA foreign_keys=off;
BEGIN TRANSACTION;
ALTER TABLE cities RENAME TO old_cities;
--CREATE TABLE cities (
-- id INTEGER NOT NULL PRIMARY KEY,
-- name TEXT NOT NULL
--);
CREATE TABLE cities (
id INTEGER NOT NULL,
name TEXT NOT NULL,
PRIMARY KEY (id)
);
SELECT * FROM old_cities;
INSERT INTO cities
SELECT id, name FROM old_cities;
DROP TABLE old_cities;
COMMIT;
You have defined the column id of the table cities to be INTEGER, but with this:
INSERT INTO cities (id, name) VALUES ('pan', 'doul');
you insert the string 'pan' as id.
SQLite does not do any type checking in this case and allows it.
Did you mean to insert 2 rows each having the names 'pan' and 'doul'?
If so, you should do something like:
INSERT INTO cities (id, name) VALUES (1, 'pan'), (2, 'doul');
Later you rename the table cities to old_cities and you recreate cities but you do something different: you define id as INTEGER and PRIMARY KEY.
This definition is the only one that forces type checking in SQLite.
So, when you try to insert the rows from old_cities to cities you get an error because 'pan' is not allowed in the column id as it is defined now.
We are dealing with legacy code that doesn't auto-increment the primary key (see serial) so I have to manually do it. What is the correct way to manually update the primary key field on insert. I am getting an error when I do the below
Table:
CREATE TABLE pizza (
id bigint not null,
price int
)
Insert statement:
INSERT INTO pizza
(id, price)
VALUES
(
(SELECT max(id) from pizza)+1,
1.75
)
Don't use max()+1 to generate a primary key. It's not safe for concurrent inserts and it doesn't really scale well.
Just create a sequence and use that:
create sequence pizza_id_seq;
Then synchronize it with the current values in the table:
select setval('pizza_id_seq', coalesce(max(id),1))
from pizza;
Then, instead of changing your INSERT statements to use the dreaded max() + 1, just use the sequence:
INSERT INTO pizza
(id, price)
VALUES
(nextval('pizza_id_seq'), 1.75)
I have a problem to insert the data into 1 table with 1 column
Name: user_id
Column: id
I am trying to add 1 line in this column with this query:
INSERT INTO user_id (id) VALUES ()
The problem is the above is invalid, I want the id take the last value id +1
This is not a syntax problem because this query works:
INSERT INTO user_id (id) VALUES (4)
So, I do not really know how to solve this problem.
Assuming the id column is defined as serial or identity you can specify a column list and set the column value to default:
insert into user_id (id) values (default);
This also works if you have more columns, e.g:
insert into users (id, firstname, lastname)
values (default, 'Arthur', 'Dent');
Or you can leave out the column list completely and request the default value(s) for all columns:
insert into user_id default values;
SQL supports the default values statement.
So this will work:
create table t (id serial primary key);
insert into t
default values;
The syntax is described in the documentation.
I have this situation,
INSERT INTO TABLE1()...
--Get the primary key from the above insert
SELECT ##identidy
INSERT INTO TABLE2()...
The auto generated primary key has to be a foreign key in TABLE 2. How can I construct my second INSERT to have the value of ##identity?
This doesn't seem to work,
INSERT INTO TABLE1 (user_id, name) (##identity, 'ABC')
I get an error saying Must declare variable '##identidy'.
Cheers!!
1) you spelled ##identity wrong (##identidy)
2) You should create a local variable (#LastIdentity) to store the last inserted identity immediately after the first insert. Then use that variable as the input to the second INSERT:
DECLARE #LastIdentity int
INSERT INTO TABLE1()...
--Get the primary key from the above insert
SELECT #LastIdentity = ##identity
INSERT INTO TABLE2(...) VALUES (#LastIdentity, ...