I would like to use the LIMIT option in my query, but the number of expected rows is stored in another table. This is what I have, but it doesn't work:
select * from table1 limit (select limitvalue from table2 where id = 1)
When I only run the subquery, the result is 6, as expected.
I prefer working with a WITH statement if possible, but that didn't work eiter.
Thank you in advance!
You could use a prepared statement to get the limit of queries from the other table because the limit clause does not allow non constant variables as parameter:
PREPARE firstQuery FROM "SELECT * FROM table1 LIMIT ?";
SET #limit = (select limitvalue from table2 where id = 1);
EXECUTE firstQuery USING #limit;
The source of the sql query from another post
You can make use of MariaDB's ROW_NUMBER function in a CTE to count the rows to be output, comparing that against the limitvalue. For example:
WITH rownums AS (
SELECT *,
ROW_NUMBER() OVER () AS rn
FROM table1
)
SELECT *
FROM rownums
WHERE rn <= (SELECT limitvalue FROM table2 WHERE id = 1)
Note Using LIMIT without ORDER BY is not guaranteed to give you the same results every time. You should include an ORDER BY clause in the OVER part of the ROW_NUMBER window function. With the sample data in my demo, you might use something like:
ROW_NUMBER() OVER (ORDER BY mark DESC)
Demo on dbfiddle
I'm trying to use values from an apex_t_numbers collection in a SELECT query as WITH subquery:
atn_cur_ids := apex_string.split_numbers(arg_v_ids, ':');
-- So if arg_v_ids := '1:2:3', then atn_cur_ids := apex_t_numbers(1, 2, 3)
with t_cur_ids as (
select * as id from table(atn_cur_ids);
)
select text from t_texts
join t_cur_ids on t_texts.id = t_cur_ids.id
And here's the problem - apex_t_numbers is a table of number, not of record type with named fields. Oracle SQL doesn't allow to give aliases to a * even if it has only one single "anonymous" column.
A possible solution could be a function that both
receives * and
returns value per row
But I am aware of only one that can get a * and return something - count(*), and it doesn't meet the second requirement.
Alright, found a solution. It could be done with column_value as a name of column:
with t_cur_ids as (
select column_value as id from table(atn_cur_ids);
)
select text from t_texts
join t_cur_ids on t_texts.id = t_cur_ids.id
I tried to apply the solution in Google BigQuery - Updating a nested repeated field to the field hits.transaction.transactionRevenue, but I receive error message:
Scalar subquery produced more than one element
I have tried to run the following query:
UPDATE `project_id.dataset_id.table`
SET hits = ARRAY(
SELECT AS STRUCT * REPLACE (
(SELECT AS STRUCT transaction.* REPLACE (1 AS transactionRevenue)) AS transaction
)
FROM UNNEST(hits) as transactionRevenue
)
WHERE (select h.transaction.transactionId from unnest(hits) as h) LIKE 'ABC123XYZ'
Are there any obvious mistakes on my part? Would be great if anyone could share some tips or experiences that could help me with this.
What I basically want to do is to set the revenue of a specific transaction to 1.
Many thanks in advance,
David
This is the problem:
WHERE (select h.transaction.transactionId from unnest(hits) as h) LIKE 'ABC123XYZ'
If there is more than one hit in the array, this will cause the error that you are seeing. You probably want this instead:
WHERE EXISTS (select 1 from unnest(hits) as h WHERE h.transaction.transactionId LIKE 'ABC123XYZ')
But note that your UPDATE will now replace all elements of the array for any row where this condition is true. What you may want is to move the condition inside the ARRAY function call instead:
UPDATE `project_id.dataset_id.table`
SET hits = ARRAY(
SELECT AS STRUCT * REPLACE (
(SELECT AS STRUCT transaction.* REPLACE (1 AS transactionRevenue)) AS transaction
)
FROM UNNEST(hits) as h
WHERE h.transaction.transactionId LIKE 'ABC123XYZ'
)
WHERE true
Now the replacement will only apply to hits with a transaction ID matching the pattern.
here is my query
select *
from table
where id in ( select string_agg(CAST(id as varchar), '","') FROM table)
string_agg() is completely useless and unnecessary for that:
select *
from table_one
where id in (select id FROM other_table)
I assume you are doing that for two different tables, otherwise that would be a very expensive way of writing: select * from table where id is not null
I am trying to use an Insert, Sequence and Select * to work together.
INSERT INTO BRK_INDV
Select * from (Select brk_seq.NEXTVAL as INDV_SEQ, a.*
FROM (select to_date(to_char(REQUEST_DATETIME,'DD-MM-YYYY'),'DD-MM-YYYY') BUSINESS_DAY, to_char(REQUEST_DATETIME,'hh24') src_hour,
CASE tran_type
WHEN 'V' THEN 'Visa'
WHEN 'M' THEN 'MasterCard'
ELSE tran_type
end text,
tran_type, count(*) as count
from DLY_STATS
where 1=1
AND to_date(to_char(REQUEST_DATETIME,'DD-MM-YYYY'),'DD-MM-YYYY') = '09-FEB-2015'
group by to_date(to_char(REQUEST_DATETIME,'DD-MM-YYYY'),'DD-MM-YYYY'),to_char(REQUEST_DATETIME,'hh24'),tran_type order by src_hour)a);
This gives me the following error:
ERROR at line 2:
ORA-02287: sequence number not allowed here
I tried to remove the order by and still the same error.
However, if I only run
Select brk_seq.NEXTVAL as INDV_SEQ, a.*
FROM (select to_date(to_char(REQUEST_DATETIME,'DD-MM-YYYY'),'DD-MM-YYYY') BUSINESS_DAY, to_char(REQUEST_DATETIME,'hh24') src_hour,
CASE tran_type
WHEN 'V' THEN 'Visa'
WHEN 'M' THEN 'MasterCard'
ELSE tran_type
end text,
tran_type, count(*) as count
from DLY_STATS
where 1=1
AND to_date(to_char(REQUEST_DATETIME,'DD-MM-YYYY'),'DD-MM-YYYY') = '09-FEB-2015'
group by to_date(to_char(REQUEST_DATETIME,'DD-MM-YYYY'),'DD-MM-YYYY'),to_char(REQUEST_DATETIME,'hh24'),tran_type order by src_hour)a;
It shows me proper entries. Then, why is select * not working for that?
Kindly help.
I see what you're trying to do. You want to insert rows into the BRK_INDV table in a particular order. The sequence number, which I assume will be the primary key of BRK_INDV, will be generated sequentially in the sorted order of the input rows.
You are working with a relational database. One of the first characteristics we all learn about a relational database is that the order of the rows in a table is insignificant. That's just a fancy word for fugitaboutit.
You cannot assume that a select * from table will return the rows in the same order they were written. It might. It might for quite a long time. Then something -- the number of rows, the grouping of some column values, the phase of the moon -- something will change and you will get them out in a seemingly totally random order.
If you want order, it must be imposed in the query, not the insert.
Here's the statement you should be executing:
INSERT INTO BRK_INDV
With
Grouped( Business_Day, Src_Hour, Text, Tran_Type, Count )As(
Select Trunc( Request_Datetime ) Business_Day,
To_Char( Request_Datetime, 'hh24') Src_Hour,
Case Tran_Type
When 'V' Then 'Visa'
When 'M' Then 'MasterCard'
Else Tran_Type
end Text,
Tran_Type, count(*) as count
from DLY_STATS
Where 1=1 --> Generated as dynamic SQL?
And Request_Datetime >= Date '2015-02-09'
And Request_Datetime < Date '2015-02-10'
Group By Trunc( Request_Datetime ), To_Char( Request_Datetime, 'hh24'), Tran_Type
)
Select brk_seq.Nextval Indv_Seq, G.*
from Grouped G;
Notice there is no order by. If you want to see the generated rows in a particular order:
select * from Brk_Indv order by src_hour;
Since there could be hundreds or thousands of transactions in any particular hour, you probably order by something other than hour anyway.
In Oracle, the trunc function is the best way to get a date with the time portion stripped away. However, you don't want to use it in the where clause (or, aamof, any other function such as to_date or to_char)as that would make the clause non-sargable and result in a complete table scan.
The problem is that you can't use a sequence in a subquery. For example, this gives the same ORA-02287 error you are getting:
create table T (x number);
create sequence s;
insert into T (select * from (select s.nextval from dual));
What you can do, though, is create a function that returns nextval from the sequence, and use that in a subquery:
create function f return number as
begin
return s.nextval;
end;
/
insert into T (select * from (select f() from dual));