Let's imagine that we have a plpgsql (PostgreSQL 10.7) function where there is a query like
INSERT INTO "myTable"
SELECT * FROM "anotherTable"
INNER JOIN "otherTable"
...
So, this query will insert several rows into myTable. In the next query I want to collect the ids which were inserted with some condition. So, my idea was to do it the following:
INSERT INTO "resultTable" rt
SELECT FROM "myTable"
INNER JOIN ...
WHERE rt."id" >= firstInsertedId;
Now the question: how to find this firstInsertedId?
My solution:
select nextval(''"myTable.myTable_id_seq"'') into firstInsertedId;
if firstInsertedId > 1 then
perform setval(''"myTable.myTable_id_seq"'', (firstInsertedId - 1));
end if;
I don't really like the solution as I don't think that it is good for the performance to generate the id, then go back, then generate it again during the insertion.
Thoughts:
was thinking about inserting the ids into variable array and then find the minimum, but no luck.
was considering to use lastval() function, but it seems that it doesn'
t work for me even though in a very similar implementation in MySQL LAST_INSERT_ID() worked just fine.
Any suggestions?
You can do both things in a single statement using a data modifying common table expression. You don't really need PL/pgSQL for that.
with new_rows as (
INSERT INTO my_table
SELECT *
FROM anotherTable
JOIN "otherTable" ...
returning my_table.id
)
insert into resulttable (new_id)
select id
from new_rows;
Another option would be to store the generate IDs in an array.
declare
l_ids integer[];
begin
....
with new_rows as (
INSERT INTO my_table
SELECT *
FROM anotherTable
JOIN "otherTable" ...
returning my_table.id
)
select array_agg(id)
into l_ids
from new_rows;
....
end;
Related
I'm using below minus query to get the extra project_ids present in TABLE_ONE compared to TABLE_TWO
select project_id from TABLE_ONE minus select project_id from TABLE_TWO;
I want to store result of above query which is list of varchars in a variable since i need to perform below 2 steps :
If above query returns any project_ids, send an email which contains these project_ids in mail body
insert those extra project_ids in TABLE_TWO to make sure all project_ids present in TABLE_ONE are present in TABLE_TWO
For step 2 I tried below query and it worked.
insert into TABLE_TWO columns (project_id) values (select project_id from TABLE_ONE minus select project_id from TABLE_TWO);
However to perform above 2 steps i need to store the query result in a variable. Please let me know how to do it. I'm using Oracle 12c.
Unfortunately, neither of the two most natural ways to get the missing IDs into table_two (a multi-row INSERT or a MERGE) support the RETURNING.. BULK COLLECT INTO clause.
So, I think your best bet is to get the list of ids first and then use that list to maintain table_two.
Like this:
DECLARE
l_missing_id_list SYS.ODCINUMBERLIST;
BEGIN
SELECT project_id
BULK COLLECT INTO l_missing_id_list
FROM
(
SELECT t1.project_id FROM table_one t1
MINUS
SELECT t2.project_id FROM table_two t2 );
FORALL i IN l_missing_id_list.FIRST..l_missing_id_list.LAST
INSERT INTO table_two VALUES ( l_missing_id_list(i) );
COMMIT;
-- Values are now inserted and you have the list of IDs in l_missing_id_list to add to your email.
END;
That's the basic concept. Presumably you have more columns in TABLE_TWO than just the id, so you'll have to add those.
something like this. Use a cursor loop.
begin
for c_record in (select project_id from TABLE_ONE minus select project_id from TABLE_TWO)
loop
-- send your email however it is done using c_record.project_id
insert into TABLE_TWO columns (project_id) values (c_record.project_id);
end loop;
FYI, there is a disadvantage to doing it this way potentially. If you send the email and then the transaction is rolled back, the email still went out the door.
A more robust way would be to use Oracle Advances Queues, but that starts getting complicated pretty fast.
SELECT LISTAGG(project_id,',') WITHIN GROUP (ORDER BY project_id)
FROM (select project_id from TABLE_ONE minus select project_id from TABLE_TWO) x;
I am trying to update one table from another, im able to update fine as long as the customer record exists, but there are some entries that dont.
To solve this i've tried running the following insert
SELECT *
INTO SalBudgetCust
FROM SalBudgetCust_temp
WHERE NOT EXISTS (
SELECT Customer
FROM SalBudgetCust
WHERE Customer = SalBudgetCust_temp.Customer
)
but im prompted with
There is already an object named 'SalBudgetCust' in the database.
Im stuck at this point... could anyone offer a little guideance?
SELECT INTO implicitly creates the table you name. You should instead use INSERT INTO ... SELECT * FROM ..., so that the existing table is used.
It should be INSERT INTO instead of SELECT * INTO ... like
INSERT INTO SalBudgetCust SELECT * FROM SalBudgetCust_temp
WHERE NOT EXISTS
(
SELECT Customer FROM SalBudgetCust WHERE Customer = SalBudgetCust_temp.Customer
)
The general syntax to insert data of one table into another is :
INSERT INTO new_table
SELECT * FROM old_table
WHERE some_condition;
Where, new_table is the table where you want to insert data, old_table is table from where you are fetching data and some_condition is the expression / condition based upon which you want to fetch data from old table.
You may use other clauses like order by, group by, and even sub queries after where clause.
May refer this SQL INSERT INTO and it's subsequent pages.
I Can't run this query with SQLite
if 0<(select COUNT(*) from Repetition where (Word='behnam' and Topic='mine'))
begin
update Repetition set Counts=1+ (select Counts from Repetition where (Word='behnam' and Topic='mine'))
end
else
begin
insert Repetition(Word,Topic,Counts)values('behnam','mine',1)
end
It says "Syntax error near IF"
How can I solve the problem
SQLite does not have an IF statement (see the list of supported queries)
Insetad, check out out ERIC B's suggestion on another thread. You're effectively looking at doing an UPSERT (UPdate if the record exists, INSERT if not). Eric B. has a good example of how to do this in SQLite syntax utilizing the "INSERT OR REPLACE" functionality in SQLite. Basically, you'd do something like:
INSERT OR REPLACE INTO Repetition (Word, Topic, Counts)
VALUES ( 'behnam', 'mine',
coalesce((select Counts + 1 from Repetition
where Word = 'behnam', AND Topic = 'mine)
,1)
)
Another approach is to INSERT ... SELECT ... WHERE ... EXISTS [or not] (SELECT ...);
I do this sort of thing all the time, and I use jklemmack's suggestion as well. And I do it for other purposes too, such as doing JOINs in UPDATEs (which SQLite3 does not support).
For example:
CREATE TABLE t(id INTEGER PRIMARY KEY, c1 TEXT NOT NULL UNIQUE, c2 TEXT);
CREATE TABLE r(c1 TEXT NOT NULL UNIQUE, c2 TEXT);
INSERT OR REPLACE INTO t (id, c1, c2)
SELECT t.id, coalesce(r.c1, t.c1), coalesce(r.c2, t.c2)
FROM r LEFT OUTER JOIN t ON r.c1 = t.c1
WHERE r.c2 = #param;
The WHERE there has the condition that you'd have in your IF. The JOIN in the SELECT provides the JOIN that SQLite3 doesn't support in UPDATE. The INSERT OR REPLACE and the use of t.id (which can be NULL if the row doesn't exist in t) together provide the THEN and ELSE bodies.
You can apply this over and over. If you'd have three statements (that cannot somehow be merged into one) in the THEN part of the IF you'd need to have three statements with the IF condition in their WHEREs.
This is called an UPSERT (i.e. UPdate or inSERT). It has its forms in almost every type of database. Look at this question for the SQLite version: SQLite - UPSERT *not* INSERT or REPLACE
One way that I've found is based on SQL WHERE clause true/false statement:
SELECT * FROM SOME_TABLE
WHERE
(
SELECT SINGLE_COLUMN_NAME FROM SOME_OTHER_TABLE
WHERE
SOME_COLUMN = 'some value' and
SOME_OTHER_COLUMN = 'some other value'
)
This actually means execute some QUERIES if some other QUERY returns 'any' result.
Given a database like this:
BEGIN TRANSACTION;
CREATE TABLE aTable (
a STRING,
b STRING
);
INSERT INTO aTable VALUES('one','two');
INSERT INTO aTable VALUES('one','three');
CREATE TABLE anotherTable (
a STRING,
b STRING
);
INSERT INTO anotherTable VALUES('one','three');
INSERT INTO anotherTable VALUES('two','three');
COMMIT;
I would like to do something along the lines of
SELECT a,b FROM aTable
WHERE (aTable.a,aTable.b) IN
(SELECT anotherTable.a,anotherTable.b FROM anotherTable);
To get the answer 'one','three', but I'm getting "near ",": syntax error"
Is this possible in any flavour of SQL? (I'm using SQLite)
Am I making a gross conceptual error? Or what?
your code works if you do it in PostgreSQL or Oracle. on MS SQL, it is not supported
use this:
SELECT a,b FROM aTable
WHERE
-- (aTable.a,aTable.b) IN -- leave this commented, it makes the intent more clear
EXISTS
(
SELECT anotherTable.a,anotherTable.b -- do not remove this too, perfectly fine for self-documenting code, i.e.. tuple presence testing
FROM anotherTable
WHERE anotherTable.a = aTable.a AND anotherTable.b = aTable.b
);
[EDIT]
sans the stating of intent:
SELECT a,b FROM aTable
WHERE
EXISTS
(
SELECT *
FROM anotherTable
WHERE anotherTable.a = aTable.a AND anotherTable.b = aTable.b
);
it's somewhat lame, for more than a decade, MS SQL still don't have first-class support for tuples. IN tuple construct is way more readable than its analogous EXISTS construct. btw, JOIN also works (tster's code), but if you need something more flexible and future-proof, use EXISTS.
[EDIT]
speaking of SQLite, i'm dabbling with it recently. yeah, IN tuples doesn't work
you can use a join:
SELECT aTable.a, aTable.b FROM aTable
JOIN anotherTable ON aTable.a = anotherTable.a AND aTable.b = anotherTable.b
Another alternative is to use concatenation to make your 2-tuple into a single field :
SELECT a,b FROM aTable
WHERE (aTable.a||'-'||aTable.b) IN
(SELECT (anotherTable.a || '-' || anotherTable.b FROM anotherTable);
...just be aware that bad things can happen if a or b contain the delimiter '-'
Is there a better solution to the problem of looking up multiple known IDs in a table:
SELECT * FROM some_table WHERE id='1001' OR id='2002' OR id='3003' OR ...
I can have several hundreds of known items. Ideas?
SELECT * FROM some_table WHERE ID IN ('1001', '1002', '1003')
and if your known IDs are coming from another table
SELECT * FROM some_table WHERE ID IN (
SELECT KnownID FROM some_other_table WHERE someCondition
)
The first (naive) option:
SELECT * FROM some_table WHERE id IN ('1001', '2002', '3003' ... )
However, we should be able to do better. IN is very bad when you have a lot of items, and you mentioned hundreds of these ids. What creates them? Where do they come from? Can you write a query that returns this list? If so:
SELECT *
FROM some_table
INNER JOIN ( your query here) filter ON some_table.id=filter.id
See Arrays and Lists in SQL Server 2005
ORs are notoriously slow in SQL.
Your question is short on specifics, but depending on your requirements and constraints I would build a look-up table with your IDs and use the EXISTS predicate:
select t.id from some_table t
where EXISTS (select * from lookup_table l where t.id = l.id)
For a fixed set of IDs you can do:
SELECT * FROM some_table WHERE id IN (1001, 2002, 3003);
For a set that changes each time, you might want to create a table to hold them and then query:
SELECT * FROM some_table WHERE id IN
(SELECT id FROM selected_ids WHERE key=123);
Another approach is to use collections - the syntax for this will depend on your DBMS.
Finally, there is always this "kludgy" approach:
SELECT * FROM some_table WHERE '|1001|2002|3003|' LIKE '%|' || id || '|%';
In Oracle, I always put the id's into a TEMPORARY TABLE to perform massive SELECT's and DML operations:
CREATE GLOBAL TEMPORARY TABLE t_temp (id INT)
SELECT *
FROM mytable
WHERE mytable.id IN
(
SELECT id
FROM t_temp
)
You can fill the temporary table in a single client-server roundtrip using Oracle collection types.
We have a similar issue in an application written for MS SQL Server 7. Although I dislike the solution used, we're not aware of anything better...
'Better' solutions exist in 2008 as far as I know, but we have Zero clients using that :)
We created a table valued user defined function that takes a comma delimited string of IDs, and returns a table of IDs. The SQL then reads reasonably well, and none of it is dynamic, but there is still the annoying double overhead:
1. Client concatenates the IDs into the string
2. SQL Server parses the string to create a table of IDs
There are lots of ways of turning '1,2,3,4,5' into a table of IDs, but the Stored Procedure which uses the function ends up looking like...
CREATE PROCEDURE my_road_to_hell #IDs AS VARCHAR(8000)
AS
BEGIN
SELECT
*
FROM
myTable
INNER JOIN
dbo.fn_split_list(#IDs) AS [IDs]
ON [IDs].id = myTable.id
END
The fastest is to put the ids in another table and JOIN
SELECT some_table.*
FROM some_table INNER JOIN some_other_table ON some_table.id = some_other_table.id
where some_other_table would have just one field (ids) and all values would be unique