All my tables use UUID primary keys. I want to fill tables with test data in one sql file, but can't use UUID PK as FK in other tables, because default function uuid_generate_v4() generates a random value during execution.
Example what I want:
SET Uservar = uuid_generate_v4();
SET Postvar = uuid_generate_v4();
INSERT INTO public."User" (id, name) VALUES (Uservar, 'Foo Bar');
INSERT INTO public."Post" (id, content, userId) VALUES (Postvar, 'Test message', Uservar)
How to do this? Or how to select already created UUID and store for next insert?
E.g. say you had table like this:
create table my_table(uuid_column uuid PRIMARY KEY NOT NULL);
You can insert a variablized uuid like so:
DO $$
DECLARE
my_uuid uuid = uuid_generate_v4();
BEGIN
insert into my_table (uuid_column) values (my_uuid);
select * from my_table where uuid_column = my_uuid;
END $$;
Check this documentation.
N.B. To have uuid_generate_v4() available, make sure you have the below snipped ran before your use it:
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
When you combine both INSERTs into a single statement you can re-use the uuid values quite easily:
WITH newUser(id uuid) AS (
INSERT INTO public."User" (id, name)
VALUES (uuid_generate_v4(), 'Foo Bar')
RETURNING id
)
INSERT INTO public."Post" (id, content, userId)
SELECT uuid_generate_v4(), 'Test message', id
FROM newUser;
When you want to add a post for an existing user, you can use a very similar approach:
INSERT INTO public."Post" (id, content, userId)
SELECT uuid_generate_v4(), 'Test message', id
FROM public."User"
WHERE name = 'Foo Bar';
This would also work when the PK's are auto-generated (i.e. id uuid PRIMARY KEY DEFAULT uuid_generate_v4()) but then you would not explicitly include the PK columns in the INSERT statements.
As I cannot comment
it should be
DO $$
DECLARE
my_uuid uuid := uuid_generate_v4();
BEGIN
insert into my_table (uuid_column) values (my_uuid);
select * from my_table where uuid_column = my_uuid;
END $$;
Related
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.
How to use IF statement in the PostgreSql (11 version)? I tried just raw IF usage but got problem (syntax error at or near “IF”). To resolve this problem people propose to use 'do &&' but it does not work as well (Unterminated dollar quote started at position 3 in SQL DO $$ BEGIN IF ......). Here is my SQL code:
DO $$
BEGIN
IF (NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'categories')) THEN
CREATE TABLE IF NOT EXISTS categories
(
id SERIAL NOT NULL,
name character varying(40),
CONSTRAINT categories_pkey PRIMARY KEY (id)
);
INSERT INTO categories (name) VALUES ('Games');
INSERT INTO categories (name) VALUES ('Multimedia');
INSERT INTO categories (name) VALUES ('Productivity');
INSERT INTO categories (name) VALUES ('Tools');
INSERT INTO categories (name) VALUES ('Health');
INSERT INTO categories (name) VALUES ('Lifestyle');
INSERT INTO categories (name) VALUES ('Other');
END IF;
END
$$;
All I need is to create table and insert some init data to it if table does not exist.
Some platforms do not support dollar quoting. In your specific example you should have a semicolon after the last END. You may need to add a DECLARE statement also.
DO
$$
DECLARE
BEGIN
IF (NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'categories'))
THEN
CREATE TABLE IF NOT EXISTS categories
(
id SERIAL NOT NULL,
name character varying(40),
CONSTRAINT categories_pkey PRIMARY KEY (id)
);
INSERT INTO categories (name) VALUES ('Games');
INSERT INTO categories (name) VALUES ('Multimedia');
INSERT INTO categories (name) VALUES ('Productivity');
INSERT INTO categories (name) VALUES ('Tools');
INSERT INTO categories (name) VALUES ('Health');
INSERT INTO categories (name) VALUES ('Lifestyle');
INSERT INTO categories (name) VALUES ('Other');
END IF;
END;
$$ LANGUAGE PLPGSQL;
For platforms that don't recognize dollar quoting you can use ' instead. You'll need to escape any ' in the body of the anonymous function though.
Like so:
DO
'
DECLARE
BEGIN
IF (NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = ''categories''))
THEN
CREATE TABLE IF NOT EXISTS categories
(
id SERIAL NOT NULL,
name character varying(40),
CONSTRAINT categories_pkey PRIMARY KEY (id)
);
INSERT INTO categories (name) VALUES (''Games'');
INSERT INTO categories (name) VALUES (''Multimedia'');
INSERT INTO categories (name) VALUES (''Productivity'');
INSERT INTO categories (name) VALUES (''Tools'');
INSERT INTO categories (name) VALUES (''Health'');
INSERT INTO categories (name) VALUES (''Lifestyle'');
INSERT INTO categories (name) VALUES (''Other'');
END IF;
END;
' LANGUAGE PLPGSQL;
DBFiddle to view a working example.
I have the same issue in play framework evolution, fixed by adding additional semicolon
$BODY$
BEGIN
if NEW.year_after IS NULL THEN
NEW.year_after := 100;;
NEW.after := 200;;
end if;;
RETURN NEW;;
END;;
$BODY$ language plpgsql
I'm posting this here as this is the first result on Google when searching for this problem on Delphi's FireDAC.
My issue was that the function had comments with accented characters, and after removing those comments, the "Unterminated dollar quote" error went away. So be careful with UTF8 characters in comments.
I would also like to note that I've had similar problems with operators that use special characters, like the !~ (NOT SIMILAR TO) operator, which was wrongfully sent to PostgreSQL as the ~ (SIMILAR TO) operator.
The upsert works using on conflict but the datatype of id is serial meaning I want to have it auto-generated/incremented. If I do the insert without specifying id the insert works fine.
The problem I have is combining the two. To get the key auto incremented I do not pass the id into the insert but if I do not pass id then the update will never fire. I cannot pass null to id as it is non-null field.
In below example - I run the query first time and it does insert and second time it does update but I cannot figure out how to pass 'nothing' to insert so the identity key still works on insert. I can put DEFAULT in the insert but then I cannot pass a real id value if there is one.
CREATE TABLE public.upsert_test
(
id INTEGER NOT NULL DEFAULT nextval('upsert_test_id_seq'::regclass),
name character varying(20) COLLATE pg_catalog."default",
description character varying(20) COLLATE pg_catalog."default",
CONSTRAINT upsert_test_pkey PRIMARY KEY (id)
)
INSERT INTO upsert_test (id, name, description)
VALUES (1, 'thing1', 'test')
on conflict (id)
do update set (name , description) = ('thing_updated','test-updated')
where upsert_test.id = 1;
You can change your query to use sequence functions like:
INSERT INTO upsert_test (id, name, description)
VALUES ((select nextval('upsert_test_id_seq')), 'thing1', 'test')
on conflict (id)
do update set (name , description) = ('thing_updated','test-updated')
where upsert_test.id = (select currval('upsert_test_id_seq'));
Note this may not be threadsafe, for eg if second call to this sql is executed before select currval('upsert_test_id_seq') in first call, then the update may fail in first query.
Update after more information from op
You can change the query to like this:
INSERT INTO upsert_test (id, name, description)
VALUES (COALESCE(:YOUR_ID_PARAM, (select nextval('upsert_test_id_seq'))), 'thing1', 'test')
on conflict (id)
do update set (name , description) = ('thing_updated','test-updated')
where upsert_test.id = :YOUR_ID_PARAM;
Note I added the coalesce function so if your parameter is null then use sequence nextval. Also, the update now also uses your parameter.
Let's say I have the following PostgreSQL table:
id | key
---+--------
1 | 'a.b.c'
I need to prevent inserting records with a key that is a prefix of another key. For example, I should be able to insert:
'a.b.b'
But the following keys should not be accepted:
'a.b'
'a.b.c'
'a.b.c.d'
Is there a way to achieve this - either by a constraint or by a locking mechanism (check the existance before inserting)?
This solution is based on PostgreSQL user-defined operators and exclusion constraints (base syntax, more details).
NOTE: more testing shows this solution does not work (yet). See bottom.
Create a function has_common_prefix(text,text) which will calculate logically what you need. Mark the function as IMMUTABLE.
CREATE OR REPLACE FUNCTION
has_common_prefix(text,text)
RETURNS boolean
IMMUTABLE STRICT
LANGUAGE SQL AS $$
SELECT position ($1 in $2) = 1 OR position ($2 in $1) = 1
$$;
Create an operator for the index
CREATE OPERATOR <~> (
PROCEDURE = has_common_prefix,
LEFTARG = text,
RIGHTARG = text,
COMMUTATOR = <~>
);
Create exclusion constraint
CREATE TABLE keys ( key text );
ALTER TABLE keys
ADD CONSTRAINT keys_cannot_have_common_prefix
EXCLUDE ( key WITH <~> );
However, the last point produces this error:
ERROR: operator <~>(text,text) is not a member of operator family "text_ops"
DETAIL: The exclusion operator must be related to the index operator class for the constraint.
This is because to create an index PostgreSQL needs logical operators to be bound with physical indexing methods, via entities calles "operator classes". So we need to provide that logic:
CREATE OR REPLACE FUNCTION keycmp(text,text)
RETURNS integer IMMUTABLE STRICT
LANGUAGE SQL AS $$
SELECT CASE
WHEN $1 = $2 OR position ($1 in $2) = 1 OR position ($2 in $1) = 1 THEN 0
WHEN $1 < $2 THEN -1
ELSE 1
END
$$;
CREATE OPERATOR CLASS key_ops FOR TYPE text USING btree AS
OPERATOR 3 <~> (text, text),
FUNCTION 1 keycmp (text, text)
;
ALTER TABLE keys
ADD CONSTRAINT keys_cannot_have_common_prefix
EXCLUDE ( key key_ops WITH <~> );
Now, it works:
INSERT INTO keys SELECT 'ara';
INSERT 0 1
INSERT INTO keys SELECT 'arka';
INSERT 0 1
INSERT INTO keys SELECT 'barka';
INSERT 0 1
INSERT INTO keys SELECT 'arak';
psql:test.sql:44: ERROR: conflicting key value violates exclusion constraint "keys_cannot_have_common_prefix"
DETAIL: Key (key)=(arak) conflicts with existing key (key)=(ara).
INSERT INTO keys SELECT 'bark';
psql:test.sql:45: ERROR: conflicting key value violates exclusion constraint "keys_cannot_have_common_prefix"
DETAIL: Key (key)=(bark) conflicts with existing key (key)=(barka).
NOTE: more testing shows this solution does not work yet: The last INSERT should fail.
INSERT INTO keys SELECT 'a';
INSERT 0 1
INSERT INTO keys SELECT 'ac';
ERROR: conflicting key value violates exclusion constraint "keys_cannot_have_common_prefix"
DETAIL: Key (key)=(ac) conflicts with existing key (key)=(a).
INSERT INTO keys SELECT 'ab';
INSERT 0 1
You can use ltree module to achieve this, it will let you to create hierarchical tree-like structures. Also will help you to prevent from reinventing the wheel, creating complicated regular expressions and so on. You just need to have postgresql-contrib package installed. Take a look:
--Enabling extension
CREATE EXTENSION ltree;
--Creating our test table with a pre-loaded data
CREATE TABLE test_keys AS
SELECT
1 AS id,
'a.b.c'::ltree AS key_path;
--Now we'll do the trick with a before trigger
CREATE FUNCTION validate_key_path() RETURNS trigger AS $$
BEGIN
--This query will do our validation.
--It'll search if a key already exists in 'both' directions
--LIMIT 1 because one match is enough for our validation :)
PERFORM * FROM test_keys WHERE key_path #> NEW.key_path OR key_path <# NEW.key_path LIMIT 1;
--If found a match then raise a error
IF FOUND THEN
RAISE 'Duplicate key detected: %', NEW.key_path USING ERRCODE = 'unique_violation';
END IF;
--Great! Our new row is able to be inserted
RETURN NEW;
END;
$$ LANGUAGE plpgsql;
CREATE TRIGGER test_keys_validator BEFORE INSERT OR UPDATE ON test_keys
FOR EACH ROW EXECUTE PROCEDURE validate_key_path();
--Creating a index to speed up our validation...
CREATE INDEX idx_test_keys_key_path ON test_keys USING GIST (key_path);
--The command below will work
INSERT INTO test_keys VALUES (2, 'a.b.b');
--And the commands below will fail
INSERT INTO test_keys VALUES (3, 'a.b');
INSERT INTO test_keys VALUES (4, 'a.b.c');
INSERT INTO test_keys VALUES (5, 'a.b.c.d');
Of course I did not bother creating primary key and other constraints for this test. But do not forget to do so. Also, there is much more on ltree module than I'm showing, if you need something different take a look on its docs, perhaps you'll find the answer there.
You can try below trigger. Please note that key is sql reserve word. So I would suggest you avoid using that as column name in your table.
I have added my create table syntax also for testing purpose:
CREATE TABLE my_table
(myid INTEGER, mykey VARCHAR(50));
CREATE FUNCTION check_key_prefix() RETURNS TRIGGER AS $check_key_prefix$
DECLARE
v_match_keys INTEGER;
BEGIN
v_match_keys = 0;
SELECT COUNT(t.mykey) INTO v_match_keys
FROM my_table t
WHERE t.mykey LIKE CONCAT(NEW.mykey, '%')
OR NEW.mykey LIKE CONCAT(t.mykey, '%');
IF v_match_keys > 0 THEN
RAISE EXCEPTION 'Prefix Key Error occured.';
END IF;
RETURN NEW;
END;
$check_key_prefix$ LANGUAGE plpgsql;
CREATE TRIGGER check_key_prefix
BEFORE INSERT OR UPDATE ON my_table
FOR EACH ROW
EXECUTE PROCEDURE check_key_prefix();
Here is a CHECK - based solution - it may satisfy your needs.
CREATE TABLE keys ( id serial primary key, key text );
CREATE OR REPLACE FUNCTION key_check(text)
RETURNS boolean
STABLE STRICT
LANGUAGE SQL AS $$
SELECT NOT EXISTS (
SELECT 1 FROM keys
WHERE key ~ ( '^' || $1 )
OR $1 ~ ( '^' || key )
);
$$;
ALTER TABLE keys
ADD CONSTRAINT keys_cannot_have_common_prefix
CHECK ( key_check(key) );
PS. Unfortunately, it fails in one point (multi - row inserts).
SQL is a very powerful language. Usually you can do most of the things by plain select statements. I.e. if you do not like triggers, you can use a this method for your inserts.
The only assumption is there exists at least 1 row in the table. (*)
The table:
create table my_table
(
id integer primary key,
key varchar(100)
);
Because of the assumption, we'll have at least 1 row.(*)
insert into my_table (id, key) values (1, 'a.b.c');
Now the magic sql. The trick is replace the p_key value by your key value to insert. I have, intentionally, not put that statement into a stored procedure. Because I want it to be straight forward if you want to carry it to your application side. But usually putting sql into stored procedure is better.
insert into my_table (id, key)
select (select max(id) + 1 from my_table), p_key
from my_table
where not exists (select 'p' from my_table where key like p_key || '%' or p_key like key || '%')
limit 1;
Now the tests:
-- 'a.b.b' => Inserts
insert into my_table (id, key)
select (select max(id) + 1 from my_table), 'a.b.b'
from my_table
where not exists (select 'p' from my_table where key like 'a.b.b' || '%' or 'a.b.b' like key || '%')
limit 1;
-- 'a.b' => does not insert
insert into my_table (id, key)
select (select max(id) + 1 from my_table), 'a.b'
from my_table
where not exists (select 'p' from my_table where key like 'a.b' || '%' or 'a.b' like key || '%')
limit 1;
-- 'a.b.c' => does not insert
insert into my_table (id, key)
select (select max(id) + 1 from my_table), 'a.b.c'
from my_table
where not exists (select 'p' from my_table where key like 'a.b.c' || '%' or 'a.b.c' like key || '%')
limit 1;
-- 'a.b.c.d' does not insert
insert into my_table (id, key)
select (select max(id) + 1 from my_table), 'a.b.c.d'
from my_table
where not exists (select 'p' from my_table where key like 'a.b.c.d' || '%' or 'a.b.c.d' like key || '%')
limit 1;
(*) If you wish you can get rid of this existence of the single row by introducing an Oracle like dual table. If you wish modifying the insert statement is straight forward. Let me know if you wish to do so.
One possible solution is to create a secondary table that holds the prefixes of your keys, and then use a combination of unique and exclusion constraints with an insert trigger to enforce the uniqueness semantics you want.
At a high level, this approach breaks each key down into a list of prefixes and applies something similar to readers-writer lock semantics: any number of keys may share a prefix as long as none of the keys equals the prefix. To accomplish that, the list of prefixes includes the key itself with a flag that marks it as a terminal prefix.
The secondary table looks like this. We use a CHAR rather than a BOOLEAN for the flag because later on we’ll be adding a constraint that doesn’t work on boolean columns.
CREATE TABLE prefixes (
id INTEGER NOT NULL,
prefix TEXT NOT NULL,
is_terminal CHAR NOT NULL,
CONSTRAINT prefixes_id_fk
FOREIGN KEY (id)
REFERENCES your_table (id)
ON DELETE CASCADE,
CONSTRAINT prefixes_is_terminal
CHECK (is_terminal IN ('t', 'f'))
);
Now we’ll need to define a trigger on insert into your_table to also insert rows into prefixes, such that
INSERT INTO your_table (id, key) VALUES (1, ‘abc');
causes
INSERT INTO prefixes (id, prefix, is_terminal) VALUES (1, 'a', ‘f’);
INSERT INTO prefixes (id, prefix, is_terminal) VALUES (1, 'ab', ‘f’);
INSERT INTO prefixes (id, prefix, is_terminal) VALUES (1, 'abc', ’t’);
The trigger function might look like this. I’m only covering the INSERT case here, but the function could be made to handle UPDATE as well by deleting the old prefixes and then inserting the new ones. The DELETE case is covered by the cascading foreign-key constraint on prefixes.
CREATE OR REPLACE FUNCTION insert_prefixes() RETURNS TRIGGER AS $$
DECLARE
is_terminal CHAR := 't';
remaining_text TEXT := NEW.key;
BEGIN
LOOP
IF LENGTH(remaining_text) <= 0 THEN
EXIT;
END IF;
INSERT INTO prefixes (id, prefix, is_terminal)
VALUES (NEW.id, remaining_text, is_terminal);
is_terminal := 'f';
remaining_text := LEFT(remaining_text, -1);
END LOOP;
RETURN NEW;
END;
$$ LANGUAGE plpgsql;
We add this function to the table as a trigger in the usual way.
CREATE TRIGGER insert_prefixes
AFTER INSERT ON your_table
FOR EACH ROW
EXECUTE PROCEDURE insert_prefixes();
An exclusion constraint and a partial unique index will enforce that a row where is_terminal = ’t’ can't collide with another row of the same prefix regardless of its is_terminal value, and that there's only one row with is_terminal = ’t’:
ALTER TABLE prefixes ADD CONSTRAINT prefixes_forbid_conflicts
EXCLUDE USING gist (prefix WITH =, is_terminal WITH <>);
CREATE UNIQUE INDEX ON prefixes (prefix) WHERE is_terminal = 't';
This allows new rows that don’t conflict but prevents ones that do conflict, including in multi-row INSERTs.
db=# INSERT INTO your_table (id, key) VALUES (1, 'a.b.c');
INSERT 0 1
db=# INSERT INTO your_table (id, key) VALUES (2, 'a.b.b');
INSERT 0 1
db=# INSERT INTO your_table (id, key) VALUES (3, 'a.b');
ERROR: conflicting key value violates exclusion constraint "prefixes_forbid_conflicts"
db=# INSERT INTO your_table (id, key) VALUES (4, 'a.b.c');
ERROR: duplicate key value violates unique constraint "prefixes_prefix_idx"
db=# INSERT INTO your_table (id, key) VALUES (5, 'a.b.c.d');
ERROR: conflicting key value violates exclusion constraint "prefixes_forbid_conflicts"
db=# INSERT INTO your_table (id, key) VALUES (6, 'a.b.d'), (7, 'a');
ERROR: conflicting key value violates exclusion constraint "prefixes_forbid_conflicts"
I want to fill out empty notification_settings for each user that already exists. IDs (PKs) are auto-generated by Hibernate in each table. Here is the user Table :
CREATE TABLE lottery_user (
id int8 not null,
email varchar(255) not null,
password varchar(255) not null,
notification_settings_id int8,
role varchar (50) default 'USER',
registry_date TIMESTAMP default now(),
primary key (id)
ADD CONSTRAINT FK_USER_TO_NOTIFICATION_SETTINGS
FOREIGN KEY (notification_settings_id) REFERENCES notification_settings
);
And here is the notification_settings table which I need to fill out for users that don't have it filled out for them.
CREATE TABLE notification_settings (
id int8 not NULL ,
test1_events bool DEFAULT TRUE ,
test2_events bool DEFAULT TRUE ,
test3_events bool DEFAULT TRUE ,
test4_events bool DEFAULT TRUE ,
PRIMARY KEY (id)
);
Basically, I need to use "INSERT INTO notification_settings (test1_events, test2_events, test3_events, test4_events) VALUES (True, True, True, True)" something similar to that. And of course, condition should be something like this "where these rows are empty for users". I can't seem to get Syntax right.
BIG NOTE: SQL code is for presentation purpose, so you can have an idea what kind of tables I have. I just need to get INSERT script right. Tables are working fine, just need to generate notification_settings values for users that already exist.
Another Note: Using Flyway, so it's not just about Hibernate. If that has to do with anything.
Are you just looking for:
INSERT INTO notification_settings (id)
SELECT id
FROM user
WHERE id NOT IN (SELECT id FROM notifiation_settings)
You might be looking to insert into an identity field:
SET IDENTITY_INSERT my_table ON
Since your foreign key constraint goes from notification_settings to user, the condition "where these rows are empty for user X" does not apply to your schema. On the other hand - "I want to fill out empty notification_settings for each user that already exists" can be done by using an insert...select construct:
set #rank=0
select #maxid = max(id) from notification_settings
insert into notification_settings (id)
select #maxid + #rank:=#rank+1 as rank
from user
where notification_settings_id is null
What is interesting is how you put those newly generated IDs back into the user table. Homework assignment for next time :)
INSERT INTO notification_settings (id)
SELECT u.id
FROM user u
WHERE
not exists (SELECT * FROM notifiation_settings ns where ns.id=i.id)
I will answer my own question how I dealt with it. Firstly, I insert IDs into notification_settings id, then I get those IDs and set them into lottery_user table's FK (notification_settings_id). Then I just delete unneeded IDs. Yea not perfect but it works.
INSERT INTO notification_settings (id) select lu.id from lottery_user lu where lu.id not in(select ns.id from notification_settings ns);
update lottery_user lu set notification_settings_id = (select ns.id from notification_settings ns where ns.id = lu.id) where lu.notification_settings_id is null;
delete from notification_settings ns where not exists (select * from lottery_user lu where lu.notification_settings_id = ns.id);
Also, script to Alter Sequence for new Lottery_user entities.
do $$
declare maxid int;
begin
select max(id) from lottery_user into maxid;
IF maxid IS NOT NULL THEN
EXECUTE 'ALTER SEQUENCE notification_settings_seq START with '|| maxid;
END IF;
end;
$$ language plpgsql;