How do I round number UP to the multiple of 10 in PostgreSQL easily?
Example:
In Out
100 --> 100
111 --> 120
123 --> 130
Sample data:
create table sample(mynumber numeric);
insert into sample values (100);
insert into sample values (111);
insert into sample values (123);
I can use:
select
mynumber,
case
when mynumber = round(mynumber,-1) then mynumber
else round(mynumber,-1) + 10 end as result
from
sample;
This works well, but looks ugly. Is there simpler way of doing this?
You can find SQLFiddle here
select ceil(a::numeric / 10) * 10
from (values (100), (111), (123)) s(a);
?column?
----------
100
120
130
Related
I have a table containing data that has a column named id that looks like below:
id
value 1
value 2
value 3
1
244
550
1000
1
251
551
700
1
540
60
1200
...
...
...
...
2
19
744
2000
2
10
903
100
2
44
231
600
2
120
910
1100
...
...
...
...
I want to take 50 sample rows per id that exists but if less than 50 exist for the group to simply take the entire set of data points.
For example I would like a maximum 50 data points randomly selected from id = 1, id = 2 etc...
I cannot find any previous questions similar to this but have tried taking a stab at at least logically working through the solution where I could iterate and union all queries by id and limit to 50:
SELECT * FROM (SELECT * FROM schema.table AS tbl WHERE tbl.id = X LIMIT 50) UNION ALL;
But it's obvious that you cannot use this type of solution because UNION ALL requires aggregating outputs from one id to the next and I do not have a list of id values to use in place of X in tbl.id = X.
Is there a way to accomplish this by gathering that list of unique id values and union all results or is there a more optimal way this could be done?
If you want to select a random sample for each id, then you need to randomize the rows somehow. Here is a way to do it:
select * from (
select *, row_number() over (partition by id order by random()) as u
from schema.table
) as a
where u <= 50;
Example (limiting to 3, and some row number for each id so you can see the selection randomness):
setup
DROP TABLE IF EXISTS foo;
CREATE TABLE foo
(
id int,
value1 int,
idrow int
);
INSERT INTO foo
select 1 as id, (1000*random())::int as value1, generate_series(1, 100) as idrow
union all
select 2 as id, (1000*random())::int as value1, generate_series(1, 100) as idrow
union all
select 3 as id, (1000*random())::int as value1, generate_series(1, 100) as idrow;
Selection
select * from (
select *, row_number() over (partition by id order by random()) as u
from foo
) as a
where u <= 3;
Output:
id
value1
idrow
u
1
542
6
1
1
24
86
2
1
155
74
3
2
505
95
1
2
100
46
2
2
422
33
3
3
966
88
1
3
747
89
2
3
664
19
3
In case you are looking to get 50 (or less) from each group of IDs then you can use windowing -
From question - "I want to take 50 sample rows per id that exists but if less than 50 exist for the group to simply take the entire set of data points."
Query -
with data as (
select row_number() over (partition by id order by random()) rn,
* from table_name)
select * from data where rn<=50 order by id;
Fiddle.
Your description of trying to get the UNION ALL without specifying all the branches ahead of time is aiming for a LATERAL join. And that is one way to solve the problem. But unless you have a table of all distinct ids, you would have to compute one on the fly. For example (using the same fiddle as Pankaj used):
with uniq as (select distinct id from test)
select foo.* from uniq cross join lateral
(select * from test where test.id=uniq.id order by random() limit 3) foo
This could be either slower or faster than the Window Function method, depending on your system and your data and your indexes. In my hands, it was quite a bit faster even with the need to dynamically compute the list of distinct ids.
I'm looking to dynamically insert a set of columns from one table to another in PostgreSQL. What I think I'd like to do is read in a 'checklist' of column headings (those columns which exist in table 1 - the storage table), and if they exist in the export table (table 2) then insert them in all at once from table 1. Table 2 will be variable in its columns though - once imported ill drop it and import new data to be imported with potentially different column structure. So I need to import it based on the column names.
e.g.
Table 1. - The storage table
ID NAME YEAR LITH_AGE PROV_AGE SIO2 TIO2 CAO MGO COMMENTS
1 John 1998 2000 3000 65 10 5 5 comment1
2 Mark 2005 2444 3444 63 8 2 3 comment2
3 Luke 2001 1000 1500 77 10 2 2 comment3
Table 2. - The export table
ID NAME MG# METHOD SIO2 TIO2 CAO MGO
1 Amy 4 Method1 65 10 5 5
2 Poe 3 Method2 63 8 2 3
3 Ben 2 Method3 77 10 2 2
As you can see the export table may include columns which do not exist in the storage table, so these would be ignored.
I want to insert all of these columns at once, as I've found if I do it individually by column it extends the number of rows each time on the insert (maybe someone can solve this issue instead? Currently I've written a function to check if a column name exists in table 2, if it does, insert it, but as said this extends the rows of the table every time and NULL the rest of the columns).
The INSERT line from my function:
EXECUTE format('INSERT INTO %s (%s) (SELECT %s::%s FROM %s);',_tbl_import, _col,_col,_type,_tbl_export);
As a type of 'code example' for my question:
EXECUTE FORMAT('INSERT INTO table1 (%s) (SELECT (%s) FROM table2)',columns)
where 'columns' would be some variable denoting the columns that exist in the export table that need to go into the storage table. This will be variable as table 2 will be different every time.
This would ideally update Table 1 as:
ID NAME YEAR LITH_AGE PROV_AGE SIO2 TIO2 CAO MGO COMMENTS
1 John 1998 2000 3000 65 10 5 5 comment1
2 Mark 2005 2444 3444 63 8 2 3 comment2
3 Luke 2001 1000 1500 77 10 2 2 comment3
4 Amy NULL NULL NULL 65 10 5 5 NULL
5 Poe NULL NULL NULL 63 8 2 3 NULL
6 Ben NULL NULL NULL 77 10 2 2 NULL
UPDATED answer
As my original answer did not meet requirement came out later but was asked to post an alternative example for information_schema solution so here it is.
I made two versions for solutions:
V1 - is equivalent to already given example using information_schema. But that solution relies on table1 column DEFAULTs. Meaning, if table1 column that does not exist at table2 does not have DEFAULT NULL then it will be filled with whatever the default is.
V2 - is modified to force 'NULL' in case of two table columns mismatch and does not inherit table1 own DEFAULTs
Version1:
CREATE OR REPLACE FUNCTION insert_into_table1_v1()
RETURNS void AS $main$
DECLARE
columns text;
BEGIN
SELECT string_agg(c1.attname, ',')
INTO columns
FROM pg_attribute c1
JOIN pg_attribute c2
ON c1.attrelid = 'public.table1'::regclass
AND c2.attrelid = 'public.table2'::regclass
AND c1.attnum > 0
AND c2.attnum > 0
AND NOT c1.attisdropped
AND NOT c2.attisdropped
AND c1.attname = c2.attname
AND c1.attname <> 'id';
-- Following is the actual result of query above, based on given data examples:
-- -[ RECORD 1 ]----------------------
-- string_agg | name,si02,ti02,cao,mgo
EXECUTE format(
' INSERT INTO table1 ( %1$s )
SELECT %1$s
FROM table2
',
columns
);
END;
$main$ LANGUAGE plpgsql;
Version2:
CREATE OR REPLACE FUNCTION insert_into_table1_v2()
RETURNS void AS $main$
DECLARE
t1_cols text;
t2_cols text;
BEGIN
SELECT string_agg( c1.attname, ',' ),
string_agg( COALESCE( c2.attname, 'NULL' ), ',' )
INTO t1_cols,
t2_cols
FROM pg_attribute c1
LEFT JOIN pg_attribute c2
ON c2.attrelid = 'public.table2'::regclass
AND c2.attnum > 0
AND NOT c2.attisdropped
AND c1.attname = c2.attname
WHERE c1.attrelid = 'public.table1'::regclass
AND c1.attnum > 0
AND NOT c1.attisdropped
AND c1.attname <> 'id';
-- Following is the actual result of query above, based on given data examples:
-- t1_cols | t2_cols
-- --------------------------------------------------------+--------------------------------------------
-- name,year,lith_age,prov_age,si02,ti02,cao,mgo,comments | name,NULL,NULL,NULL,si02,ti02,cao,mgo,NULL
-- (1 row)
EXECUTE format(
' INSERT INTO table1 ( %s )
SELECT %s
FROM table2
',
t1_cols,
t2_cols
);
END;
$main$ LANGUAGE plpgsql;
Also link to documentation about pg_attribute table columns if something is unclear: https://www.postgresql.org/docs/current/static/catalog-pg-attribute.html
Hopefully this helps :)
I use PostgreSQL database and have a cards table.
Each record(card) in this table have card_drop_rate integer value.
For example:
id | card_name |card_drop_rate
-------------------------------
1 |card1 |34
2 |card2 |16
3 |card3 |54
max drop rate is 34 + 16 + 54 = 104.
In accordance to my application logic I need to find a random value between 0 and 104 and then retrieve card according to this number, for example:
random value: 71
card1 range: 0 - 34(0 + 34)
card2 range: 34 - 50(34 + 16)
card3 range: 50 - 104(50 + 54)
So, my card is card3 because 71 is placed in the range 50 - 104
What is the proper way to reflect this structure in PostgreSQL ? I'll need to query this data often under so the performance is a criterion number one for this solution.
Following query works fine:
SELECT
b.id,
b.card_drop_rate
FROM (SELECT a.id, sum(a.card_drop_rate) OVER(ORDER BY id) - a.card_drop_rate as rate, card_drop_rate FROM cards as a) b
WHERE b.rate < 299 ORDER BY id DESC LIMIT 1
You can do this using cumulative sums and random. The "+ 1"s might be throwing me off, but it is something like this:
with c as (
select c.*,
sum(card_drop_rate + 1) - card_drop_rate as threshhold
from cards c
),
r as (
select random() * (sum(card_drop_rate) + count(*) - 1) as which_card
from cards c
)
select c.*
from c cross join
r
where which_card >= threshhold
order by threshhold
limit 1;
For performance, I would simply take the cards and generate a new table with 106 slots. Assign the card value to the slots and build an index on the slot number. Then get a value using:
select s.*
from slots s
where s.slotid = floor(random() * 107);
How do I write a query to update my rows 'S'. I would like to update the current Primary key to change the number of it. I am not sure if I need a sub-query.
Would updating score, use the same method to update "S"?
"S" indicates student number, "C" indicates course number.
My tried but failed query is
update grades set s = 114 where s = 100;
The 'set s' is what I want to update into and the 'where s' is looking for the row with that set 's' number. Right?
Here is my query, trigger, and select * from grades looks like.
create table grades (
S varchar2(12),
C varchar2(10),
Score number(3,0),
Letter_Grade char(1),
Constraint pk_grades primary key (S),
Constraint CK_grades check (score between 0 and 100)
constraint lg_grades check (letter_grade in ('A','B','C','D','F'))
);
SET SERVEROUTPUT ON
CREATE OR REPLACE TRIGGER MARK_BU
BEFORE UPDATE OF score ON grades
FOR EACH ROW
DECLARE
BEGIN
:NEW.letter_grade :=
CASE
WHEN :NEW.score >= 80 THEN 'A'
WHEN :NEW.score >= 70 THEN 'B'
WHEN :NEW.score >= 60 THEN 'C'
WHEN :NEW.score >= 50 THEN 'D'
ELSE 'F'
END ;
DBMS_OUTPUT.PUT_LINE ('Numeric_grade was updated to: ' || :NEW.score);
DBMS_OUTPUT.PUT_LINE ('Letter_grade was calculated to be:' || :NEW.letter_grade);
END;
S C SCORE L
------------ ---------- ---------- -
100 CST8255 49 F
101 CST8255 59 D
102 CST8255 69 C
103 CST8255 79 B
104 CST8255 89 A
update grades set s = 114 where s = 100;
Is correct it will work.
I'm trying to convert the contents of a VARCHAR field to be unique number that can be easily referenced by a 3rd party.
How can I convert a varchar to the ascii string equivalent? In TSQL? The ASCII() function converts a single character but what can I do to convert an entire string?
I've tried using
CAST(ISNULL(ASCII(Substring(RTRIM(LTRIM(PrimaryContactRegion)),1,1)),'')AS VARCHAR(3))
+ CAST(ISNULL(ASCII(Substring(RTRIM(LTRIM(PrimaryContactRegion)),2,1)),'')AS VARCHAR(3))
....but this is tedious, stupid looking, and just doesn't really work if I had long strings. Or if it is better how would I do the same thing in SSRS?
try something like this:
DECLARE #YourString varchar(500)
SELECT #YourString='Hello World!'
;WITH AllNumbers AS
(
SELECT 1 AS Number
UNION ALL
SELECT Number+1
FROM AllNumbers
WHERE Number<LEN(#YourString)
)
SELECT
(SELECT
ASCII(SUBSTRING(#YourString,Number,1))
FROM AllNumbers
ORDER BY Number
FOR XML PATH(''), TYPE
).value('.','varchar(max)') AS NewValue
--OPTION (MAXRECURSION 500) --<<needed if you have a string longer than 100
OUTPUT:
NewValue
---------------------------------------
72101108108111328711111410810033
(1 row(s) affected)
just to test it out:
;WITH AllNumbers AS
(
SELECT 1 AS Number
UNION ALL
SELECT Number+1
FROM AllNumbers
WHERE Number<LEN(#YourString)
)
SELECT SUBSTRING(#YourString,Number,1),ASCII(SUBSTRING(#YourString,Number,1)),* FROM AllNumbers
OUTPUT:
Number
---- ----------- -----------
H 72 1
e 101 2
l 108 3
l 108 4
o 111 5
32 6
W 87 7
o 111 8
r 114 9
l 108 10
d 100 11
! 33 12
(12 row(s) affected)
Also, you might want to use this:
RIGHT('000'+CONVERT(varchar(max),ASCII(SUBSTRING(#YourString,Number,1))),3)
to force all ASCII values into 3 digits, I'm not sure if this is necessary based on your usage or not.
Output using 3 digits per character:
NewValue
-------------------------------------
072101108108111032087111114108100033
(1 row(s) affected)
Well, I think that a solution to this will be very slow, but i guess that you could do something like this:
DECLARE #count INT, #string VARCHAR(100), #ascii VARCHAR(MAX)
SET #count = 1
SET #string = 'put your string here'
SET #ascii = ''
WHILE #count <= DATALENGTH(#string)
BEGIN
SELECT #ascii = #ascii + '&#' + ASCII(SUBSTRING(#string, #count, 1)) + ';'
SET #count = #count + 1
END
SET #ascii = LEFT(#ascii,LEN(#ascii)-1)
SELECT #ascii
I'm not in a pc with a database engine, so i can't really test this code. If it works, then you can create a UDF based on this.