I'm new to Presto and looking to get the same functionality as the group_concat function in MySQL. Are the following two equivalent? If not, any suggestions for how I can recreate the group_concat functionality in Presto?
MySQL:
select
a,
group_concat(b separator ',')
from table
group by a
Presto:
select
a,
array_join(array_agg(b), ',')
from table
group by a
(Found this as a suggested Presto workaround here when searching group_concat functionality.)
Try using this in place of group_concat in Presto ::
select
a,
array_join(array_agg(b), ',')
from table
group by a
Also, if you're looking for unique values only – an equivalent to group_concat(distinct ... separator ', ') – try this:
array_join(array_distinct(array_agg(...)), ', ')
There's no function as of this answer, though the feature has been requested.
The closest equivalent is mentioned in your question.
WITH tmp AS (
SELECT 'hey' AS str1
UNION ALL
SELECT ' there'
)
SELECT array_join(array_agg(str1), ',', '') AS joined
FROM tmp
Related
I m trying to get number in between "sims_7009_alaira", i want 7009.
SELECT sno,dbase, SUBSTRING_INDEX(dbase, 'sims_', -1)temp
FROM school
How should i do that in SQL
Give this a try:
select substring_index(SUBSTRING_INDEX(dbase, '_', 2),'_',-1) from school;
Check this here:
SQL Fiddle
Just use substring_index() two times:
SELECT sno, dbase, substring_index(substring_index(dbase, 'sims_', -1), '_alaira', 1) as number FROM school
Do this instead:
SELECT sno,dbase, SUBSTRING_INDEX(SUBSTRING_INDEX(dbase, "_", 2),'_',-1) temp
FROM school;
For more insight see this.
I'm migrating some MySQL code to Postgres and having a heck of a time converting the following line:
GROUP_CONCAT(
DISTINCT id,':',foo,':',bar ORDER BY id
) as id,
This results in a comma separated list of strings like:
id:foo:bar,id2:foo2:bar2
The 'DISTINCT' is there to avoid duplicates.
I've read the equivalent of GROUP_CONCAT in Postgres is string_agg, but I can't figure out how to make it work the same way.
Edit: I may have almost answered my own question. I came up with the solution of using CONCAT. The problem with this is that now sorting is done by the concatenated string rather than by the id:
string_agg(DISTINCT CONCAT(
id::text, ':', foo, ':', bar, ':'
), ',') as id
If I try to add 'ORDER BY id' I get an error.
You can do something like below.
select
string_agg(DISTINCT CONCAT(
id::text, ':', foo, ':', bar, ':'
), ',') as id from (select * from table t order by id) as al
I want to calculate distance from mysql record, firstly I get all cordinates and saved as LineString object, but I have error. What is wrong with my sql?
WITH tmp AS
(SELECT GROUP_CONCAT(CONCAT_WS(' ',lat,lng) SEPARATOR ', ') FROM track WHERE vh_id='75' AND DATE(tdate)='2016-06-09' ORDER BY tdate)
SELECT ST_Length(ST_GeomFromText(tmp));
Firstly, MySQL doesn't support the WITH clause; secondly, you should define variables like 10.4 User-Defined Variables.
You can change you sql to this;)
SELECT GROUP_CONCAT(CONCAT_WS(' ',lat,lng) SEPARATOR ', ') INTO #tmp
FROM track
WHERE vh_id='75' AND DATE(tdate)='2016-06-09' ORDER BY tdate;
SELECT ST_Length(ST_GeomFromText(#tmp));
Or just with one query:
SELECT ST_Length(ST_GeomFromText(GROUP_CONCAT(CONCAT_WS(' ',lat,lng) SEPARATOR ', ')))
FROM track
WHERE vh_id='75' AND DATE(tdate)='2016-06-09' ORDER BY tdate;
I have data in column which I want to select with substring_index and group by the result of substring. Is it possible to make in one query?:
Example
code:
R0001.10
R0001.20
R0002.10
R0002.30
If use
SELECT SUBSTRING_INDEX(code, '.', 1) FROM products;
It goes like this:
R0001
R0001
R0002
R0002
But when I use
SELECT SUBSTRING_INDEX(code, '.', 1) FROM products GROUP BY code;
It gave some strange result
01
01
010210000
0103020
etc.
There is no issue using GROUP BY clause check SQL Fiddle. Might be other issue.
I have a table with languages which s_name value looks like this:
'en_UK'
'en_US'
'de_CH'
'de_AT'
I want to get all the distinct languages, without the country part. So for example, in case I just had those of the example, I would need to get:
en
de
What would be the best way of doing so?
I have this right now:
SELECT DISTINCT SUBSTRING(name,1,2)
FROM my_languages
Try this:
SELECT DISTINCT SUBSTRING_INDEX(name, '_', 1) langName
FROM my_languages
OR
SELECT SUBSTRING_INDEX(name, '_', 1) langName
FROM my_languages
GROUP BY langName
Check this link MySQL STRING Functions
Here is a simple way:
select distinct left(s_name, 2)
from t
This assumes the language name is the left two characters.
This will work in Oracle as well as in MySql I think:
SELECT SUBSTR('en_UK',INSTR('en_UK','_')+1) country FROM dual
/