I would like to INSERT only if table exists.
Pseudocode
IF EXISTS TABLE file_headers(
INSERT INTO file_headers
(measurement_id, file_header_index_start, file_header_index_end)
VALUES (1, 1, 100);
INSERT INTO file_headers
(measurement_id, file_header_index_start, file_header_index_end)
VALUES (1, 2, 100);
... -- many INSERTs into same table
);
How can you insert only if the table exists in PostgreSQL?
do $$begin
if exists (select * from pg_catalog.pg_tables where tablename = 'mytable') then
insert into mytable (col1) values (1);
end if;
end$$;
This test would make sense if you wanted to pass table names to a function for dynamic execution.
There is a built-in solution for that: if you want to make sure the table exists, cast it to regclass (or use a regclass parameter to your function to begin with). That verifies existence and escapes possible non-standard syntax at the same time:
How to check if a table exists in a given schema
Table name as a PostgreSQL function parameter
Related
I want to create a procedure in which I insert data into several tables. I need to get the inserted ID's so I create temp table in which I catch them. The problem is that I receive an error "Invalid column name 'app_guid'" and "Invalid column name 'app_nazwa_pliku'" but I create temp tables with such columns. Do you happen to know what's wrong with my code?
create procedure p_paseczek_przenies
as
declare #new_nr_sprawy varchar(50)
if object_id('tempdb..##paseczki') is not null drop table ##paseczki
select
top 1 with ties
s.sp_numer as SprawaGlowna_sp_numer,
s.sp_id as SprawaGlowna_sp_id
,Paseczek.max_ak_id as Paseczek_max_ak_id
,apisp_data_przyjscia
,app_guid
,app_nazwa_pliku
into ##paseczki
from sprawa as s
join akcja as a on a.ak_sp_id=s.sp_id and ak_akt_id=111
join sprawa_powiazania as sp on s.sp_id=sp.sp_id and rodzaj_powiazania='SPRAWY POLUBOWNE'
join (select max(ak_id) max_ak_id,ak_sp_id from akcja
where ak_akt_id=1089
group by ak_sp_id) as Paseczek on Paseczek.ak_sp_id=sp.sp_id_powiazana
join akcja_pismo on apis_ak_id=max_ak_id
join akcja_pismo_przychodzace on apis_apisp_id=apisp_id
join akcja_pismo_plik on app_apis_id=apis_id
where s.sp_numer=#new_nr_sprawy
order by ROW_NUMBER() over (partition by s.sp_id order by paseczek.max_ak_id desc)
if exists (select * from ##paseczki)
begin
if object_id('tempdb..##akcja') is not null drop table ##akcja
create table ##akcja (
ak_id int
,apisp_data_przyjscia datetime
,app_guid varchar(max)
,app_nazwa_pliku varchar(max)
)
merge akcja as target using (
select * from ##paseczki) as source on 1=0
when not matched then insert
(ak_akt_id, ak_sp_id, ak_kolejnosc, ak_interwal, ak_zakonczono, ak_pr_id, ak_publiczna)
values (1089,SprawaGlowna_sp_id,1,1,getdate(),5,1)
output inserted.ak_id,source.apisp_data_przyjscia,source.app_guid,source.app_nazwa_pliku
into ##akcja;
insert into rezultat
(re_ak_id, re_ret_id, re_data_planowana, re_us_id_planujacy, re_data_wykonania, re_us_id_wykonujacy, re_konczy)
select ak_id,309,getdate(),5,getdate(),5,1 from ##akcja
if object_id('tempdb..##akcja_pismo_przychodzace') is not null drop table ##akcja_pismo_przychodzace
create table ##akcja_pismo_przychodzace (
apisp_id int
,ak_id int
,app_guid varchar(max)
,app_nazwa_pliku varchar(max)
)
merge akcja_pismo_przychodzace as target using (
select * from ##akcja) as source on 1=0
when not matched then insert
(apisp_data_przyjscia)
values (apisp_data_przyjscia)
output inserted.apisp_id,source.ak_id,source.app_guid,source.app_nazwa_pliku
into ##akcja_pismo_przychodzace;
if object_id('tempdb..##akcja_pismo') is not null drop table ##akcja_pismo
create table ##akcja_pismo (
apis_id int
,app_guid varchar(max)
,app_nazwa_pliku varchar(max)
)
merge akcja_pismo as target using (
select * from ##akcja_pismo_przychodzace) as source on 1=0
when not matched then insert
(apis_ak_id, apis_apisp_id, apis_data_stworzenia,[apis_us_id_tworzacy])
values (ak_id,apisp_id,getdate(),5)
output inserted.apis_id,source.app_guid,source.app_nazwa_pliku
into ##akcja_pismo;
alter table [dm_data_bps].[dbo].[akcja_pismo_plik] disable trigger [tr_akcja_pismo_plik_ins]
insert into akcja_pismo_plik
([app_guid],[app_apis_id],[app_nazwa_pliku])
select [app_guid],[apis_id],[app_nazwa_pliku] from ##akcja_pismo
alter table [dm_data_bps].[dbo].[akcja_pismo_plik] enable trigger [tr_akcja_pismo_plik_ins]
end
SQL Server compiles the procedure at creation and when it is first executed, verifying the entire procedure based on the context at that time.
For example, try the following query:
CREATE PROCEDURE P
AS
IF OBJECT_ID('tempdb..#T') IS NOT NULL DROP TABLE #T
SELECT 1 Y INTO #T
SELECT Y FROM #T
GO
CREATE TABLE #T (X INT)
GO
EXEC P
You will get an error ("Invalid column name 'Y'."), because when the procedure is compiled the table #T has only the column X.
To avoid this problem, you should make sure that the table #T either does not exist or has the right columns, before the procedure is executed.
One way would be to have another stored procedure (a wrapper):
CREATE PROCEDURE P1
AS
SELECT 1 Y INTO #T
SELECT Y FROM #T
GO
CREATE PROCEDURE P2
AS
IF OBJECT_ID('tempdb..#T') IS NOT NULL DROP TABLE #T
EXEC P1
GO
CREATE TABLE #T (X INT)
GO
EXEC P2
GO
DROP PROCEDURE P1, P2
--DROP TABLE #T
Another way would be to use dynamic SQL, because that code is compiled separately, as if it would be another stored procedure.
A better way would be to make sure that temp tables are uniquely named in each stored procedure, unless sharing data between them is desired. For the later case, you can read http://www.sommarskog.se/share_data.html#temptables for more insights.
This error is also encountered when a stored procedure creates a #temp table and then fires a trigger which creates a #temp table with the same name. The SP #temp table is referenced by the trigger when the column names are explicit, (like SELECT id FROM #temp;), but the local trigger #temp table is referenced when SELECT * FROM #temp; is used.
Microsoft, if you are listening, could you kindly attend to it and retrofit existing supported versions with a maintenance update?
I am writing migration script to migrate database. I have to duplicate the row by incrementing primary key considering that different database can have n number of different columns in the table. I can't write each and every column in query. If i simply just copy the row then, I am getting duplicate key error.
Query: INSERT INTO table_name SELECT * FROM table_name WHERE id=255;
ERROR: duplicate key value violates unique constraint "table_name_pkey"
DETAIL: Key (id)=(255) already exist
Here, It's good that I don't have to mention all column names. I can select all columns by giving *. But, same time I am also getting duplicate key error.
What's the solution of this problem? Any help would be appreciated. Thanks in advance.
If you are willing to type all column names, you may write
INSERT INTO table_name (
pri_key
,col2
,col3
)
SELECT (
SELECT MAX(pri_key) + 1
FROM table_name
)
,col2
,col3
FROM table_name
WHERE id = 255;
Other option (without typing all columns , but you know the primary key ) is to CREATE a temp table, update it and re-insert within a transaction.
BEGIN;
CREATE TEMP TABLE temp_tab ON COMMIT DROP AS SELECT * FROM table_name WHERE id=255;
UPDATE temp_tab SET pri_key_col = ( select MAX(pri_key_col) + 1 FROM table_name );
INSERT INTO table_name select * FROM temp_tab;
COMMIT;
This is just a DO block but you could create a function that takes things like the table name etc as parameters.
Setup:
CREATE TABLE public.t1 (a TEXT, b TEXT, c TEXT, id SERIAL PRIMARY KEY, e TEXT, f TEXT);
INSERT INTO public.t1 (e) VALUES ('x'), ('y'), ('z');
Code to duplicate values without the primary key column:
DO $$
DECLARE
_table_schema TEXT := 'public';
_table_name TEXT := 't1';
_pk_column_name TEXT := 'id';
_columns TEXT;
BEGIN
SELECT STRING_AGG(column_name, ',')
INTO _columns
FROM information_schema.columns
WHERE table_name = _table_name
AND table_schema = _table_schema
AND column_name <> _pk_column_name;
EXECUTE FORMAT('INSERT INTO %1$s.%2$s (%3$s) SELECT %3$s FROM %1$s.%2$s', _table_schema, _table_name, _columns);
END $$
The query it creates and runs is: INSERT INTO public.t1 (a,b,c,e,f) SELECT a,b,c,e,f FROM public.t1. It's selected all the columns apart from the PK one. You could put this code in a function and use it for any table you wanted, or just use it like this and edit it for whatever table.
How to construct an INSERT statement so that it would not generate the error "insert or update on table ... violates foreign key constraint" in case if the foreign key value does not exist in the reference table?
I just need no record created in this case and success response.
Thank you
Use a query as the source for the INSERT statement:
insert into the_table (id, some_data, some_fk_column
select *
from (
values (42, 'foobar', 100)
) as x(id, some_data, some_fk_column)
where exists (select *
from referenced_table rt
where rt.primary_key_column = x.some_fk_column);
This can also be extended to a multi-row insert:
insert into the_table (id, some_data, some_fk_column
select *
from (
values
(42, 'foobar', 100),
(24, 'barfoo', 101)
) as x(id, some_data, some_fk_column)
where exists (select *
from referenced_table rt
where rt.primary_key_column = x.some_fk_column);
You didn't show us your table definitions so I had to make up the table and column names. You will have to translate that to your names.
You could create a function with plpgsql, which inserts a row and catches the exception:
CREATE FUNCTION customInsert(int,varchar) RETURNS VOID
AS $$
BEGIN
INSERT INTO foo VALUES ($1,$2);
EXCEPTION
WHEN foreign_key_violation THEN --do nothing
END;
$$ LANGUAGE plpgsql
You can then call this function by this:
SELECT customInsert(1,'hello');
This function tries to insert the given parameters into the table foo and catches the foreign_key_violation error if occurs.
Of course you can generalise the function more, to be able to insert in more than one table, but your question sounded like this was only needed for one specific table.
I have a PostgeresDB with the following constraint:
CONSTRAINT "Car_Data_3PM_pkey" PRIMARY KEY ("F_ID", "Date"),
CONSTRAINT "Car_Data_3PM_F_ID_fkey" FOREIGN KEY ("F_ID")
REFERENCES "Bike_Data" ("F_ID") MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
When I try to insert multiple values using:
INSERT INTO "Car_Data_3PM" ("F_ID","Date","Price_Type","O","H","L","LT","EQ","V","NAD") VALUES (38,'2016-10-02 08:19:40.056679','x',0,0,0,112.145,0,0,112.145),(14,'2016-10-02 08:19:40.056679','x',0,0,0,5476,0,0,5476),(13,'2016-10-02
I get this error:
ERROR: insert or update on table "Car_Data_3PM" violates foreign key
constraint "Car_Data_3PM_F_ID_fkey" SQL state: 23503 Detail: Key
(F_ID)=(38) is not present in table "Bike_Data".
NO ROWS are inserted.
How can I make Postgres ONLY miss out the rows where the constraint is an issue? i.e Insert most of them?
You can't make Postgres ignore the values, but you can rewrite your statement to not insert those rows:
INSERT INTO "Car_Data_3PM" ("F_ID","Date","Price_Type","O","H","L","LT","EQ","V","NAD")
select *
from (
VALUES
(38,'2016-10-02 08:19:40.056679','x',0,0,0,112.145,0,0,112.145),
(14,'2016-10-02 08:19:40.056679','x',0,0,0,5476,0,0,5476),
... -- all other rows
) as x (id, date, price_type, o, h, l, lt, eq, v nad)
where exists (select 1
from "Bike_Data" bd
where bd."F_ID" = x .id)
One way is to write a trigger that filters out the bad values, like this:
CREATE FUNCTION car_insert_filter() RETURNS trigger
LANGUAGE plpgsql AS
$$BEGIN
IF EXISTS(SELECT 1 FROM "Bike_Data" WHERE "F_ID" = NEW."F_ID")
THEN
RETURN NEW;
ELSE
RAISE NOTICE 'Skipping row with "F_ID"=% and "Date"=%',
NEW."F_ID", NEW."Date";
RETURN NULL;
END IF;
END;$$;
CREATE TRIGGER car_insert_filter
BEFORE INSERT ON "Car_Data_3PM" FOR EACH ROW
EXECUTE PROCEDURE car_insert_filter();
It is expected to now take in a table called waypoints and follow through the function body.
drop function if exists everything(waypoints);
create function everything(waypoints) RETURNS TABLE(node int, xy text[]) as $$
BEGIN
drop table if exists bbox;
create temporary table bbox(...);
insert into bbox
select ... from waypoints;
drop table if exists b_spaces;
create temporary table b_spaces(
...
);
insert into b_spaces
select ...
drop table if exists b_graph; -- Line the error flags.
create temporary table b_graph(
...
);
insert into b_graph
select ...
drop table if exists local_green;
create temporary table local_green(
...
);
insert into local_green
...
with aug_temp as (
select ...
)
insert into b_graph(source, target, cost) (
(select ... from aug_temp)
UNION
(select ... from aug_temp)
);
return query
with
results as (
select id1, ... from b_graph -- The relation being complained about.
),
pkg as (
select loc, ...
)
select id1, array_agg(loc)
from pkg
group by id1;
return;
END;
$$ LANGUAGE plpgsql;
This returns cannot DROP TABLE b_graph because it is being used by active queries in this session
How do I go about rectifying this issue?
The error message is rather obvious, you cannot drop a temp table while it is being used.
You might be able to avoid the problem by adding ON COMMIT DROP:
Temporary table and loops in a function
However, this can probably be simpler. If you don't need all those temp tables to begin with (which I suspect), you can replace them all with CTEs (or most of them probably even with cheaper subqueries) and simplify to one big query. Can be plpgsql or just SQL:
CREATE FUNCTION everything(waypoints)
RETURNS TABLE(node int, xy text[]) AS
$func$
WITH bbox AS (SELECT ... FROM waypoints) -- not the fct. parameter!
, b_spaces AS (SELECT ... )
, b_graph AS (SELECT ... )
, local_green AS (SELECT ... )
, aug_temp AS (SELECT ... )
, b_graph2(source, target, cost) AS (
SELECT ... FROM b_graph
UNION ALL -- guessing you really want UNION ALL
SELECT ... FROM aug_temp
UNION ALL
SELECT ... FROM aug_temp
)
, results AS (SELECT id1, ... FROM b_graph2)
, pkg AS (SELECT loc, ... )
SELECT id1, array_agg(loc)
FROM pkg
GROUP BY id1
$func$ LANGUAGE sql;
Views are just storing a query ("the recipe"), not the actual resulting values ("the soup").
It's typically cheaper to use CTEs instead of creating temp tables.
Derived tables in queries, sorted by their typical overall performance (exceptions for special cases involving indexes). From slow to fast:
CREATE TABLE
CREATE UNLOGGED TABLE
CREATE TEMP TABLE
CTE
subquery
UNION would try to fold duplicate rows. Typically, people really want UNION ALL, which just appends rows. Faster and does not try to remove dupes.