When using a Table Value Constructor (http://msdn.microsoft.com/en-us/library/dd776382(v=sql.100).aspx) to insert multiple rows, is the order of any identity column populated guaranteed to match the rows in the TVC?
E.g.
CREATE TABLE A (a int identity(1, 1), b int)
INSERT INTO A(b) VALUES (1), (2)
Are the values of a guaranteed by the engine to be assigned in the same order as b, i.e. in this case so they match a=1, b=1 and a=2, b=2.
Piggybacking on my comment above, and knowing that the behavior of an insert / select+order by will guarantee generation of identity order (#4: from this blog)
You can use the table value constructor in the following fashion to accomplish your goal (not sure if this satisfies your other constraints) assuming you wanted your identity generation to be based on category id.
insert into thetable(CategoryId, CategoryName)
select *
from
(values
(101, 'Bikes'),
(103, 'Clothes'),
(102, 'Accessories')
) AS Category(CategoryID, CategoryName)
order by CategoryId
It depends as long as your inserting the records in one shot . For example after inserting if you delete the record where a=2 and then again re insert the value b=2 ,then identity column's value will be the max(a)+1
To demonstrate
DECLARE #Sample TABLE
(a int identity(1, 1), b int)
Insert into #Sample values (1),(2)
a b
1 1
2 2
Delete from #Sample where a=2
Insert into #Sample values (2)
Select * from #Sample
a b
1 1
3 2
Related
I have a table cusers with a primary key:
primary key(uid, lid, cnt)
And I try to insert some values into the table:
insert into cusers (uid, lid, cnt, dyn, ts)
values
(A, B, C, (
select C - cnt
from cusers
where uid = A and lid = B
order by ts desc
limit 1
), now())
on conflict do nothing
Quite often (with the possibility of 98%) a row cannot be inserted to cusers because it violates the primary key constraint, so hard select queries do not need to be executed at all. But as I can see PostgreSQL first counts the select query as a result of dyn column and only then rejects row because of uid, lid, cnt violation.
What is the best way to insert rows quickly in such situation?
Another explanation
I have a system where one row depends on another. Here is an example:
(x, x, 2, 2, <timestamp>)
(x, x, 5, 3, <timestamp>)
Two columns contain an absolute value (2 and 5) and relative value (2, 5 - 2). Each time I insert new row it should:
avoid same rows (see primary key constraint)
if new row differs, it should count a difference and put it into the dyn column (so I take the last inserted row for the user according to the timestamp and subtract values).
Another solution I've found is to use returning uid, lid, ts for inserts and get user ids which were really inserted - this is how I know they have differences from existing rows. Then I update inserted values:
update cusers
set dyn = (
select max(cnt) - min(cnt)
from (
select cnt
from cusers
where uid = A and lid = B
order by ts desc
limit 2) Table
)
where uid = A and lid = B and ts = TS
But it is not a fast approach either, as it seeks all over the ts column to find the two last inserted rows for each user. I need a fast insert query as I insert millions of rows at a time (but I do not write duplicates).
What the solution can be? May be I need a new index for this? Thanks in advance.
My table has the below sample data:
DECLARE #FHTable table (PK_ID int,FK_ID int,P_ID int, T_ID int, A_day int,A_hour TIME,D_day int,D_hour time)
INSERT INTO #FHtable VALUES (129,194,252,1005322,NULL,NULL,1,'02:30:00.0000000')
INSERT INTO #FHtable VALUES (130,194,311,1000891,3,'04:30:00.0000000',null,null)
INSERT INTO #FHtable VALUES (131,194,311,1000129,NULL,NULL,4,'03:30:00.0000000')
INSERT INTO #FHtable VALUES (132,194,252,1000025,6,'03:00:00.0000000',null,null)
SELECT * FROM #FHtable
My final result Should be of the below table:
DECLARE #FinalResultTable TABLE (FK_ID int,P_IDFrom int,P_IDTO INT, T_IDFrom int,T_IDTo INT, A_day int,A_hour TIME,D_day int,D_hour time)
INSERT INTO #FinalResultTable VALUES (194,252,311,1005322,1000891,3,'04:30:00.0000000',1,'02:30:00.0000000')
INSERT INTO #FinalResultTable VALUES (194,311,252,1000129,1000025,6,'03:00:00.0000000',4,'03:30:00.0000000')
select * from #FinalResultTable
The logic is there will be 4 rows for each FK_ID. The first and the second row is a source to destination and the 3rd and 4th row is again a source to destination.
Can you please help
As I pointed out in the comments, it's not very clear what is the logic that joins each arrival with the corresponding departure.
What it's clear to me it's that your title is wrong: you are not talking about converting rows to columns. Instead, you are just grouping 2 by 2 the rows of the table. So, you have 2 approaches, using a GROUP BY or just using a JOIN, it depends on what is exactly your logic.
Here is an example:
select A.FK_ID,
A.PK_ID as P_IDFrom, B.PK_ID as P_IDTO,
A.T_ID as T_IDFrom int, B.T_ID as T_IDTo,
B.A_day, B.A_hour,
A.D_day, A.D_hour
from #FHTable A
join #FHTable B on B.PK_ID+1=A.PK_ID
where A.A_day is null
(this assumes that an arrivals's PK is always +1 w.r.t. its departure).
I need to create a table using postgres that multiplies a row by the difference of the numbers in 2 columns, and provides the corresponding sequence. It's hard to explain, I'll leave a picture to save us a thousand words:
I have found a partial answer to this question in SQL, but it only multiplies by one column, and I'm having trouble with using it in Posgresql:
How to multiply a single row with a number from column in sql.
You can use the generate_series function: https://www.postgresql.org/docs/current/static/functions-srf.html
create table table_a(
a integer primary key,
start_a integer,
end_a integer
);
insert into table_a values
(1, 1, 3),
(2, 2, 5);
create table table_b as
select a, start_a, end_a, g as start_b, g+1 as end_b
from table_a, lateral generate_series(start_a, end_a-1) g;
select * from table_b;
You can try it here: http://rextester.com/RTZWK4070
I have a table with many(+1000) columns and rows(~1M). The columns have either the value 1 , or are NULL.
I want to be able to select, for a specific row (user) retrieve the column names that have a value of 1.
Since there are many columns on the table, specifying the columns would yield a extremely long query.
You're doing something SQL is quite bad at - dynamic access to columns, or treating a row as a set. It'd be nice if this were easier, but it doesn't work well with SQL's typed nature and the concept of a relation. Working with your data set in its current form is going to be frustrating; consider storing an array, json, or hstore of values instead.
Actually, for this particular data model, you could probably use a bitfield. See bit(n) and bit varying(n).
It's still possible to make a working query with your current model PostgreSQL extensions though.
Given sample:
CREATE TABLE blah (id serial primary key, a integer, b integer, c integer);
INSERT INTO blah(a,b,c) VALUES (NULL, NULL, 1), (1, NULL, 1), (NULL, NULL, NULL), (1, 1, 1);
I would unpivot each row into a key/value set using hstore (or in newer PostgreSQL versions, the json functions). SQL its self provides no way to dynamically access columns, so we have to use an extension. So:
SELECT id, hs FROM blah, LATERAL hstore(blah) hs;
then extract the hstores to sets:
SELECT id, k, v FROM blah, LATERAL each(hstore(blah)) kv(k,v);
... at which point your can filter for values matching the criteria. Note that all columns have been converted to text, so you may want to cast it back:
SELECT id, k FROM blah, LATERAL each(hstore(blah)) kv(k,v) WHERE v::integer = 1;
You also need to exclude id from matching, so:
regress=> SELECT id, k FROM blah, LATERAL each(hstore(blah)) kv(k,v) WHERE v::integer = 1 AND
k <> 'id';
id | k
----+---
1 | c
2 | a
2 | c
4 | a
4 | b
4 | c
(6 rows)
I'm using oracle database and facing a problem where two id_poduct.nextval is creating as error: ORA-00001: unique constraint (SYSTEM.SYS_C004166) violated
It is a primary key. To use all is a requirement. Can I use 2 .nextval in a statement?
insert all
into sale_product values (id_product.nextval, id.currval, 'hello', 123, 1)
into sale_product values (id_product.nextval, id.currval, 'hi', 123, 1)
select * from dual;
insert into sale_product
select id_product.nextval, id.currval, a, b, c
from
(
select 'hello' a, 123 b, 1 c from dual union all
select 'hi' a, 123 b, 1 c from dual
);
This doesn't use the insert all syntax, but it works the same way if you are only inserting into the same table.
The value of id_product.NEXTVAL in the first INSERT is the same as the second INSERT, hence you'll get the unique constraint violation. if you remove the constraint and perform the insert, you'll notice the duplicate values!
The only way is to perform two bulk INSERTS in sequence or to have two seperate sequences with a different range, the latter would require an awful lot of coding and checking.
create table temp(id number ,id2 number);
insert all
into temp values (supplier_seq.nextval, supplier_seq.currval)
into temp values (supplier_seq.nextval, supplier_seq.currval)
select * from dual;
ID ID2
---------- ----------
2 2
2 2
Refrence
The subquery of the multitable insert statement cannot use a sequence
http://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_9014.htm#i2080134