I'm making a database with PostgreSQL. In one of the attributes in a tables it should be possible to insert numbers: "+" and "-", but no other chars like "A", "B" or "!".
Is it possible to check the input when I'm using the INSERT INTO function?
I don't know because I'm just a beginner in Postgre and didn't find a solution in the internet.
Thanks if anybody knows an answer!
Instead of a trigger, you could use a CHECK constraint on the column's value. (or even make it a domain or type)
CREATE TABLE meuk
( id serial NOT NULL PRIMARY KEY
, thefield varchar CHECK (thefield SIMILAR TO e'[0-9\+\-]+' )
);
INSERT INTO meuk(thefield) VALUES ('1234');
INSERT INTO meuk(thefield) VALUES ('+1234');
INSERT INTO meuk(thefield) VALUES ('-1234');
INSERT INTO meuk(thefield) VALUES ('-1234a'); -- this one should fail
SELECT * FROM meuk;
Related
I have a table called person with primary key on id;
I am trying to insert into this table with:
insert into person (first_name, last_name, email, gender, date_of_birth, country_of_birth) values ('Ellissa', 'Gordge', 'ggordge0#gnu.org', 'Male', '2022-03-19', 'Fiji');
There should not be any ID constraint which are being violated since it is a BIGSERIAL yet I am getting this:
It says Key id=(8) already exists and it is incrementing on each attempt to run this command. How can ID already exist? And why is it not incrementing from the bottom of the list?
If i specify the id in the insert statement, with a number which i know is unique it works. I just don't understand why is it not doing it automatically since I am using BIGSERIAL.
Your sequence apparently is out of sync with the values in the column. This can happen when someone did INSERT INTO person(id, …) VALUES (8, …) (or maybe a csv COPY import, or anything else that did provide values for the id column instead of using the default), or when someone did reset the sequence of having inserted data.
You can alter the sequence to fix this:
ALTER SEQUENCE person_id_seq RESTART WITH (SELECT MAX(id)+1 FROM person);
You can set the sequence value to fix this:
SELECT setval('person_id_seq', MAX(id)+1) FROM person;
Also notice that it is recommended to use an identity column rather than a serial one to avoid this kind of problem.
SELECT pg_catalog.setval(pg_get_serial_sequence('table_name', 'id'), MAX(id)) FROM table_name;
This should kickstart your sequence table back in sync, which should fix everything. Make sure to change 'table_name' to the actual name. Cheers!
Assuming, I have this table:
CREATE TABLE IF NOT EXISTS public.test
(
"Id" smallint NOT NULL GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
"Value" character varying(10)
);
and I insert some rows:
INSERT INTO public.test ("Id", "Value") VALUES
(1, 'Val1'),
(2, 'Val2'),
(3, 'Val3');
Everything is fine. But now I want to insert another row
INSERT INTO public.test ("Value") VALUES ('Val9');
and I get the error: duplicate key violates unique constraint
That is, how I learned, because the pk-sequence is out of sync. But why? Is there any senseful reason why pg do not update the sequence automatically? After single INSERTs it works well, but after BULK not? Is there any way to avoid these manually updates? Or is it standard to correct every pk-sequence of every table after every little bulk insert (if there is a serial id)?
For futher information, I use GENERATED BY DEFAULT because I want to migrate a database from mysql and I want to preserve the IDs. And I would like the idea of having a lot of flexibility with the keys (similar to mysql).
But what do I not understand here?
Is it possible to correct the sequence automatically without knowing it's concrete name?
Sorry, more questions than I wanted to ask. But ... I don't understand this concept. Would appreciate some explanation.
The problem is the BY DEFAULT in GENERATED BY DEFAULT AS IDENTITY. That means that you can override the automatically generated keys, like your INSERT statements do.
When that happens, the sequence that implements the identity column is not modified. So when you insert a row without specifying "Id", it will start counting at 1, which causes the conflict.
Never override the default. To make sure this doesn't happen by accident, use GENERATED ALWAYS AS IDENTITY.
I have a simple test table
CREATE TABLE TEST (
KEY INTEGER PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY (START WITH 1, INCREMENT BY 1),
INTENTS VARCHAR(255),
NO_FOUND SMALLINT );
I am then trying to insert data into this table using the following command from within dashDB's sql dashboard.
Insert into table from (select item1,item2,item3 from TEST2 where some_condition );
However I cannot seem to get the command to not return an error.
Have tried the db2 'DEFAULT', and '0' (default for integer), and even NULL as values for item1.
Have also tried the insert using values, but then the column headings cause the system to report multiple values returned.
Have also tried 'OVERRIDING USER VALUE'
but this then complains about not finding a JOIN element.
Any ideas welcome.
I would try something like this:
Insert into test(intents,no_found)
(select item2,item3 from TEST2 where some_condition );
You specify that only two of the three columns receive values, the KEY column is generated. Hence you only select the two related columns.
We're in process of converting over from SQL Server to Postgres. I have a scenario that I am trying to accommodate. It involves inserting records from one table into another, WITHOUT listing out all of the columns. I realize this is not recommended practice, but let's set that aside for now.
drop table if exists pk_test_table;
create table public.pk_test_table
(
recordid SERIAL PRIMARY KEY NOT NULL,
name text
);
--example 1: works and will insert a record with an id of 1
insert into pk_test_table values(default,'puppies');
--example 2: fails
insert into pk_test_table
select first_name from person_test;
Error I receive in the second example:
column "recordid" is of type integer but expression is of type
character varying Hint: You will need to rewrite or cast the
expression.
The default keyword will tell the database to grab the next value.
Is there any way to utilize this keyword in the second example? Or some way to tell the database to ignore auto-incremented columns and just them be populated like normal?
I would prefer to not use a subquery to grab the next "id".
This functionality works in SQL Server and hence the question.
Thanks in advance for your help!
If you can't list column names, you should instead use the DEFAULT keyword, as you've done in the simple insert example. This won't work with a in insert into ... select ....
For that, you need to invoke nextval. A subquery is not required, just:
insert into pk_test_table
select nextval('pk_test_table_id_seq'), first_name from person_test;
You do need to know the sequence name. You could get that from information_schema based on the table name and inferring its primary key, using a function that takes just the table name as an argument. It'd be ugly, but it'd work. I don't think there's any way around needing to know the table name.
You're inserting value into the first column, but you need to add a value in the second position.
Therefore you can use INSERT INTO table(field) VALUES(value) syntax.
Since you need to fetch values from another table, you have to remove VALUES and put the subquery there.
insert into pk_test_table(name)
select first_name from person_test;
I hope it helps
I do it this way via a separate function- though I think I'm getting around the issue via the table level having the DEFAULT settings on a per field basis.
create table public.pk_test_table
(
recordid integer NOT NULL DEFAULT nextval('pk_test_table_id_seq'),
name text,
field3 integer NOT NULL DEFAULT 64,
null_field_if_not_set integer,
CONSTRAINT pk_test_table_pkey PRIMARY KEY ("recordid")
);
With function:
CREATE OR REPLACE FUNCTION func_pk_test_table() RETURNS void AS
$BODY$
INSERT INTO pk_test_table (name)
SELECT first_name FROM person_test;
$BODY$
LANGUAGE sql VOLATILE;
Then just execute the function via a SELECT FROM func_pk_test_table();
Notice it hasn't had to specify all the fields- as long as constraints allow it.
I am trying to insert a value in a one IDENTITY column Table in SQL Server CE 3.5. I Tried the following:
INSERT Target DEFAULT VALUES
INSERT Target (ID) VALUES (DEFAULT)
INSERT Target (ID) VALUES ()
But none of them worked. This is the SQL command I used to create the table (Using SQL Server Management Studio):
CREATE TABLE Target(
ID int NOT NULL IDENTITY (1, 1) PRIMARY KEY
);
Microsoft help site (http://msdn.microsoft.com/en-us/library/ms174633%28SQL.90%29.aspx) mentions that DEFAULT values are not valid for identity columns however they do not mention any alternative.
They mention something about uniqueidentifier and ROWGUID but I have not been able to make it work.
I would appreciate any pointers on how to solve this problem or links to documentation about valid sql commands for sql server CE.
Thank you
Using Default Values works for identity columns on the standard version of SQL. I can't see any reason why it wouldn't work on CE.
In your case you would do something like this:
Insert Into Target
Default Values
Edit:
This issue looks like it is specific to SQL CE.
The only other thing I could suggest would be to add another column to your table, such as DateInserted.
Insert Into Target (DateInserted)
Values (getdate())
This should then insert a new row thus generating a new ID.
If you can change your table structure then you could us a UniqueIdentifier instead.
Create Table Target
(
IDColumn uniqueidentifier not null
)
Insert Into Target
Values (newId())