select now() as t1,t1;
error :- ERROR: 42703: column "t1" does not exist
Result should be :
select now() as t1,t1;
7/26/2016 7/26/2016
Your query does not work because the moment you execute the select, the column t1 is not defined yet. Also, as you've tagged your question with Amazon Redshift, let me note that you won't be able to use now() but could use getdate() instead.
To solve your problem, you can either duplicate the now()/getdate() logic:
select getdate() as t1, getdate() as t1;
Or use it once from a subselect:
select t1, t1 from (select getdate() as t1);
Either one will give you:
t1 | t1
------------------------------+------------------------------
2016-07-28 06:43:46.23357+00 | 2016-07-28 06:43:46.23357+00
(1 row)
If you need the output to look exactly like you stated in your question:
select
t1
, t1
from (
select
regexp_replace(
to_char(CURRENT_DATE, 'MM/DD/YYYY') -- gives 07/26/2016
, '0([0-9]{1}\/)' -- stores "7/" in $1
, '$1'
) as t1
);
Giving:
t1 | t1
-----------+-----------
7/28/2016 | 7/28/2016
(1 row)
Related
I have a query for create table like below
DROP TABLE IF EXISTS BAJUL;
CREATE TABLE BAJUL AS (
SELECT dt_trx, row_number() OVER (ORDER BY dt_trx DESC) AS row_number
FROM stock_trx_idx
WHERE dt_trx BETWEEN '2017-01-01' AND '2017-02-28'
GROUP BY 1
ORDER BY 1 DESC);
How able to create above table with stored function in Postgresql?
I tried with below script
CREATE OR REPLACE FUNCTION my_function (dt1 DATE, dt2 DATE)
RETURNS VOID AS
$func$
BEGIN
EXECUTE format('
DROP TABLE IF EXISTS tblq;
CREATE TABLE IF NOT EXISTS tblq AS(
SELECT dt_trx, row_number() OVER (ORDER BY dt_trx DESC) AS row_number
FROM stock_trx
WHERE dt_trx BETWEEN dt1 AND dt2
GROUP BY 1
ORDER BY 1 DESC
)' );
END
$func$ LANGUAGE plpgsql;
but when I try to execute SF like below
SELECT my_function ('2017-01-01', '2017-02-28');
I got error --> ERROR: column "dt1" does not exist
Would like to seek your help.
Thanks & rgds,
Bayu
Use
format('CREATE ... WHERE dt_trx BETWEEN %L AND %L ...', dt1, dt2)
You error is obvious. In the SELECT statement,
SELECT dt_trx, row_number() OVER (ORDER BY dt_trx DESC) AS row_number
FROM stock_trx
WHERE dt_trx BETWEEN dt1 AND dt2
GROUP BY 1
ORDER BY 1 DESC
The dt1 column doesn't exist. You didn't tell him you wanted to use your variable. Try concatenate your string with your variables.
By the way, you can drop your ORDER BY if your creating a table with that statement.
I have a field called "Users", and I want to run SUM() on that field that returns the sum of all DISTINCT records. I thought that this would work:
SELECT SUM(DISTINCT table_name.users)
FROM table_name
But it's not selecting DISTINCT records, it's just running as if I had run SUM(table_name.users).
What would I have to do to add only the distinct records from this field?
Use count()
SELECT count(DISTINCT table_name.users)
FROM table_name
SQLFiddle demo
This code seems to indicate sum(distinct ) and sum() return different values.
with t as (
select 1 as a
union all
select '1'
union all
select '2'
union all
select '4'
)
select sum(distinct a) as DistinctSum, sum(a) as allSum, count(distinct a) as distinctCount, count(a) as allCount from t
Do you actually have non-distinct values?
select count(1), users
from table_name
group by users
having count(1) > 1
If not, the sums will be identical.
You can see for yourself that distinct works with the following example. Here I create a subquery with duplicate values, then I do a sum distinct on those values.
select DistinctSum=sum(distinct x), RegularSum=Sum(x)
from
(
select x=1
union All
select 1
union All
select 2
union All
select 2
) x
You can see that the distinct sum column returns 3 and the regular sum returns 6 in this example.
You can use a sub-query:
select sum(users)
from (select distinct users from table_name);
SUM(DISTINCTROW table_name.something)
It worked for me (innodb).
Description - "DISTINCTROW omits data based on entire duplicate records, not just duplicate fields." http://office.microsoft.com/en-001/access-help/all-distinct-distinctrow-top-predicates-HA001231351.aspx
;WITH cte
as
(
SELECT table_name.users , rn = ROW_NUMBER() OVER (PARTITION BY users ORDER BY users)
FROM table_name
)
SELECT SUM(users)
FROM cte
WHERE rn = 1
SQL Fiddle
Try here yourself
TEST
DECLARE #table_name Table (Users INT );
INSERT INTO #table_name Values (1),(1),(1),(3),(3),(5),(5);
;WITH cte
as
(
SELECT users , rn = ROW_NUMBER() OVER (PARTITION BY users ORDER BY users)
FROM #table_name
)
SELECT SUM(users) DisSum
FROM cte
WHERE rn = 1
Result
DisSum
9
If circumstances make it difficult to weave a "distinct" into the sum clause, it will usually be possible to add an extra "where" clause to the entire query - something like:
select sum(t.ColToSum)
from SomeTable t
where (select count(*) from SomeTable t1 where t1.ColToSum = t.ColToSum and t1.ID < t.ID) = 0
May be a duplicate to
Trying to sum distinct values SQL
As per Declan_K's answer:
Get the distinct list first...
SELECT SUM(SQ.COST)
FROM
(SELECT DISTINCT [Tracking #] as TRACK,[Ship Cost] as COST FROM YourTable) SQ
How I can make/declare/define a derived column in select query and then use it in where clause?
To define a column in an SQL query, you can use pretty much any SQL operation that returns a single value (including select statements). Here are some examples:
select 'Y' from dual;
select (5 * 3) cal_col from dual;
select (select min(col1) from table 2) calc_col from dual;
select nvl(col1, 'N') has_value from mytable;
From my experience, if you want to use a derived column in a select query, then you must define the column as part of an inner select. Here is an example:
select *
from (
select (col1 * col2) calc_col
from mytable
) data
where data.calc_col > 30
Another alternative is use the calculation within the where clause itself:
select (col1 * col2) calc_col
from mytable t
where (col1 * col2) > 30
If you are performing a count(*) operation, then you can also leverage the HAVING clause:
select field1, count(*)
from mytable
having count(*) > 3
How can I extract the values from a record as individual comuns in postgresql
SELECT
p.*,
(SELECT ROW(id,server_id,format,product_id) FROM products_images pi WHERE pi.product_id = p.id LIMIT 1) AS image
FROM products p
WHERE p.company = 1 ORDER BY id ASC LIMIT 10
Instead of
image
(3, 4, "jpeg", 7)
I would like to have
id | server_id | format | product_id
3 | 4 | jpeg | 7
Is there any way of selecting only one image for each product and return the columns directly instead of a record?
Try this:
create type xxx as (t varchar, y varchar, z int);
with a as
(
select row(table_name, column_name, (random() * 100)::int) x
from information_schema.columns
)
-- cannot cast directly to xxx, should cast to text first
select (x::text::xxx).t, (x::text::xxx).y, (x::text::xxx).z
from a
Alternatively, you can do this:
with a as
(
select row(table_name, column_name, (random() * 100)::int) x
from information_schema.columns
),
-- cannot cast directly to xxx, should cast to text first
b as (select x::text::xxx as w from a)
select
(w).t, (w).y, (w).z
from b
To select all fields:
with a as
(
select row(table_name, column_name, (random() * 100)::int) x
from information_schema.columns
),
-- cannot cast directly to xxx, should cast to text first
b as (select x::text::xxx as w from a)
select
(w).*
from b
You can do this too, but this makes the whole exercise of using ROW a pointless one when you can just remove the ROW function and re-pick it up from outside of cte/derived table. I surmised the OP's ROW came from a function; for which he should use the codes above, not the following:
with a as
(
select row(table_name, column_name, (random() * 100)::int)::xxx x
from information_schema.columns
)
select
(x).t, (x).y, (x).z
from a
Just specify the components of your struct:
SELECT a,b,c,(image).id, (image).server_id, ...
FROM (
SELECT
p.*,
(SELECT ROW(id,server_id,format,product_id) FROM products_images pi WHERE pi.product_id = p.id LIMIT 1) AS image
FROM products p
WHERE p.company = 1 ORDER BY id ASC LIMIT 10
) as subquery
But anyway, I would rework the query and use a join instead of a subclause.
SELECT DISTINCT ON (p.*) p.*,
p.id,pi.server_id,pi.format,pi.product_id
FROM products p
LEFT JOIN product_images pi ON pi.product_id = p.id
WHERE p.company = 1
ORDER BY id ASC
LIMIT 10
But I believe you have to specify all the p-fields in the distinct separately to ensure just one image is loaded per product.
Try this, will work on your existing code with minimal modification(if creating a type is a minimal modification for you ;-)
create type image_type as (id int, server_id int, format varchar, product_id int);
SELECT
p.*,
( (SELECT ROW(id,server_id,format,product_id)
FROM products_images pi
WHERE pi.product_id = p.id LIMIT 1)::text::image_type ).*
FROM products p
WHERE p.company = 1 ORDER BY id ASC LIMIT 10
Proof-of-concept code:
Create type first:
create type your_type_here as (table_name varchar, column_name varchar)
Actual code:
select
a.b,
( (select row(table_name, column_name)
from information_schema.columns limit 1)::text::your_type_here ).*
from generate_series(1,10) as a(b)
But I guess you should tackle it with GROUP BY' andMAXcombo or useDISTINCT ON` like what Daniel have posted
every table has an associated composite type of the same name
https://www.postgresql.org/docs/current/plpgsql-declarations.html#PLPGSQL-DECLARATION-ROWTYPES
So, this code
drop table if exists "#typedef_image"
;
create temp table "#typedef_image"(
id int,
server_id int,
format text,
product_id int
)
;
select (row(3, 4, 'jpeg', 7)::"#typedef_image").*
will work
Is there any way to simulate rownum in postgresql ?
Postgresql > 8.4
SELECT
row_number() OVER (ORDER BY col1) AS i,
e.col1,
e.col2,
...
FROM ...
Postgresql have limit.
Oracle's code:
select *
from
tbl
where rownum <= 1000;
same in Postgresql's code:
select *
from
tbl
limit 1000
I have just tested in Postgres 9.1 a solution which is close to Oracle ROWNUM:
select row_number() over() as id, t.*
from information_schema.tables t;
If you just want a number to come back try this.
create temp sequence temp_seq;
SELECT inline_v1.ROWNUM,inline_v1.c1
FROM
(
select nextval('temp_seq') as ROWNUM, c1
from sometable
)inline_v1;
You can add a order by to the inline_v1 SQL so your ROWNUM has some sequential meaning to your data.
select nextval('temp_seq') as ROWNUM, c1
from sometable
ORDER BY c1 desc;
Might not be the fastest, but it's an option if you really do need them.
If you have a unique key, you may use COUNT(*) OVER ( ORDER BY unique_key ) as ROWNUM
SELECT t.*, count(*) OVER (ORDER BY k ) ROWNUM
FROM yourtable t;
| k | n | rownum |
|---|-------|--------|
| a | TEST1 | 1 |
| b | TEST2 | 2 |
| c | TEST2 | 3 |
| d | TEST4 | 4 |
DEMO
I think it's possible to mimic Oracle rownum using temporary sequences.
create or replace function rownum_seq() returns text as $$
select concat('seq_rownum_',replace(uuid_generate_v4()::text,'-','_'));
$$ language sql immutable;
create or replace function rownum(r record, v_seq_name text default rownum_seq()) returns bigint as $$
declare
begin
return nextval(v_seq_name);
exception when undefined_table then
execute concat('create temporary sequence ',v_seq_name,' minvalue 1 increment by 1');
return nextval(v_seq_name);
end;
$$ language plpgsql volatile;
Demo:
select ccy_code,rownum(a.*) from (select ccy_code from currency order by ccy_code desc) a where rownum(a.*)<10;
Gives:
ZWD 1
ZMK 2
ZBH 3
ZAR 4
YUN 5
YER 6
XXX 7
XPT 8
XPF 9
Explanations:
Function rownum_seq() is immutable, called only once by PG in a query, so we get the same unique sequence name (even if the function is called thousand times in the same query)
Function rownum() is volatile and called each time by PG (even in a where clause)
Without r record parameter (which is unused), the function rownum() could be evaluated too early. That's the tricky point. Imagine, the following rownum() function:
create or replace function rownum(v_seq_name text default rownum_seq()) returns bigint as $$
declare
begin
return nextval(v_seq_name);
exception when undefined_table then
execute concat('create temporary sequence ',v_seq_name,' minvalue 1 increment by 1');
return nextval(v_seq_name);
end;
$$ language plpgsql volatile;
explain select ccy_code,rownum() from (select ccy_code from currency order by ccy_code desc) a where rownum()<10
Sort (cost=56.41..56.57 rows=65 width=4)
Sort Key: currency.ccy_code DESC
-> Seq Scan on currency (cost=0.00..54.45 rows=65 width=4)
Filter: (rownum('649aec1a-d512-4af0-87d8-23e8d8a9d982'::text) < 10)
PG apply the filter before the order. Damned!
With the first unused parameter, we force PG to order before filter:
explain select * from (select ccy_code from currency order by ccy_code desc) a where rownum(a.*)<10;
Subquery Scan on a (cost=12.42..64.36 rows=65 width=4)
Filter: (rownum(a.*, 'seq_rownum_43b5c67f_dd64_4191_b29c_372061c848d6'::text) < 10)
-> Sort (cost=12.42..12.91 rows=196 width=4)
Sort Key: currency.ccy_code DESC
-> Seq Scan on currency (cost=0.00..4.96 rows=196 width=4)
Pros:
works as an expression or in a where clause
easy to use: just pass the first record.* you have in the from
Cons:
a temporary sequence is created for each rownum() encountered, but it is removed when session ends.
performance (to discuss, row_number() over () versus nextval)
Postgresql does not have an equivalent of Oracle's ROWNUM.
In many cases you can achieve the same result by using LIMIT and OFFSET in your query.
use the limit clausule, with the offset to choose the row number -1 so if u wanna get the number 8 row so use:
limit 1 offset 7