I am new to postgres and one of my genius colleague managed to name a column in postgres table as follow
How far are you able to commute - less than 11 - 20 km
I am trying to retrieve this column in select statement as follows:
Select schema.tablename.How far are you able to commute - less than 11 - 20 km from schema.tablename
Obviously this will throw error as there are keywords such as
"are", "to"
How can I escape this nonsens? I have already searched a lot and tried with "columnname" and it isnt working.
Thank you for helping in advance!
Related
I am installing a database schema in Oracle 19c, and the installation scripts have been used repeatedly in Oracle 12 without problems.
My problem with 19c is when it runs our views script, it throws an on at some of views. The error we are seeing the not a group by expression.
We have a few views where for example we have something like this:
SELECT name, TRUNC(date) as Day
FROM sometable
GROUP BY name, TRUNC(date)
It is pointing the error at the select as though it doesn't see that the field is already in the group by expression.
As said, these queries work fine in Oracle 12 for years, it is only now when moving to 19 that we are seeing problems.
Is this a bug in 19c or does something need to be applied?
19c, you say? Can't reproduce it.
SQL> select banner from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Table you used (so that you wouldn't say that this is the culprit) (obviously, date is an invalid column name; that's reserved for the date datatype).
SQL> create table sometable as
2 select 'Little' name, sysdate datum
3 from dual
4 connect by level <= 3;
Table created.
Does query itself work? Yes:
SQL> select name, trunc(datum) as day
2 from sometable
3 group by name, trunc(datum);
NAME DAY
------ --------
Little 26.01.22
Note that - as you aren't aggregating anything - you could have used DISTINCT instead of GROUP BY:
SQL> select DISTINCT name, trunc(datum) as day
2 from sometable;
NAME DAY
------ --------
Little 26.01.22
Can I create a view? Yes:
SQL> create view v_sometable as
2 select name, trunc(datum) as day
3 from sometable
4 group by name, trunc(datum);
View created.
SQL>
As I said, I can't reproduce it.
Please, copy/paste your own SQL*Plus session (just like I did) so that we'd see what exactly you did and how Oracle responded.
I have a table like below :
create table xx (university varchar2(2), sub_uni varchar2(2), id varchar2(30), name varchar2(80))
Which has pk index on university,sub_uni,id
I wanted to perform a quick search on the name column which looked something like below:
select * from xx where upper(name) like upper('%JOHN%')
However as my table contains around 22 million records and the above query does a full table scan it takes around 20-25 seconds.
To optimize the query I now tried to use Oracle Text..
CREATE INDEX xx_name ON xx(name) INDEXTYPE IS CTXSYS.CONTEXT
After the creation of this index the query to filter records takes less than a second
select * from xx where contains(name,'JOHN') > 0
However as I am unable to locate a lot of documentation on oracle text I am worried/concerned about the other impacts of such index.
for eg. On average 5000 rows are added to this table while 10million are updated on daily basis.
Is there any impact of using Oracle Text in such scenario / is there any other way of speeding up this query.
Also I am unable to specify tablespace in the creation of domain index and when I drop it, it doesnt even show up in recyclebin!!!
Thanks in advance.
Queries I seem to be easily able to run in SQL workbench just don't work in Tableau - it's literally one java error after another... rant over.
One thing I've noticed is that Tableau keeps trying to wrap an additional SELECT which Athena doesn't recognise. I thought I could overcome this using Athena views, but that doens't seem to work either.
When I do the following in Tableau:
SELECT count(distinct uuid), category
FROM "pregnancy_analytics"."final_test_parquet"
GROUP BY category
I get the following in Athena (that throws an error - SYNTAX_ERROR: line 1:8: Column 'tableausql._col0' cannot be resolved). As I say, since it looks like Tableau is trying to "nest" the SELECT:
SELECT "TableauSQL"."_col0" AS "xcol0"
FROM (
SELECT count(distinct uuid)
FROM "pregnancy_analytics"."final_test_parquet"
WHERE category = ''
LIMIT 100
) "TableauSQL"
LIMIT 10000
NB: The error, as I said above, arises because Tableau sticks another SELECT around this to a table that doesn't exist, and as such Athena kicks up an error.
Starting to feel like Tableau is not a good fit with Athena? Is there a better suggestion perhaps?
Thanks!
I have a Postgres table that has names and addresses. Some of these name fields are both names of a couple -- for example, "John & Jane".
I am trying to write a query that pulls out only those rows where this is the case.
When I run this query, it selects 0 rows even though I know that they exist in the table:
SELECT count(*) FROM name_list where namefirst LIKE '%&%';
Does anyone know how to address this?
I am getting this error in the pg production mode, but its working fine in sqlite3 development mode.
ActiveRecord::StatementInvalid in ManagementController#index
PG::Error: ERROR: column "estates.id" must appear in the GROUP BY clause or be used in an aggregate function
LINE 1: SELECT "estates".* FROM "estates" WHERE "estates"."Mgmt" = ...
^
: SELECT "estates".* FROM "estates" WHERE "estates"."Mgmt" = 'Mazzey' GROUP BY user_id
#myestate = Estate.where(:Mgmt => current_user.Company).group(:user_id).all
If user_id is the PRIMARY KEY then you need to upgrade PostgreSQL; newer versions will correctly handle grouping by the primary key.
If user_id is neither unique nor the primary key for the 'estates' relation in question, then this query doesn't make much sense, since PostgreSQL has no way to know which value to return for each column of estates where multiple rows share the same user_id. You must use an aggregate function that expresses what you want, like min, max, avg, string_agg, array_agg, etc or add the column(s) of interest to the GROUP BY.
Alternately you can rephrase the query to use DISTINCT ON and an ORDER BY if you really do want to pick a somewhat arbitrary row, though I really doubt it's possible to express that via ActiveRecord.
Some databases - including SQLite and MySQL - will just pick an arbitrary row. This is considered incorrect and unsafe by the PostgreSQL team, so PostgreSQL follows the SQL standard and considers such queries to be errors.
If you have:
col1 col2
fred 42
bob 9
fred 44
fred 99
and you do:
SELECT col1, col2 FROM mytable GROUP BY col1;
then it's obvious that you should get the row:
bob 9
but what about the result for fred? There is no single correct answer to pick, so the database will refuse to execute such unsafe queries. If you wanted the greatest col2 for any col1 you'd use the max aggregate:
SELECT col1, max(col2) AS max_col2 FROM mytable GROUP BY col1;
I recently moved from MySQL to PostgreSQL and encountered the same issue. Just for reference, the best approach I've found is to use DISTINCT ON as suggested in this SO answer:
Elegant PostgreSQL Group by for Ruby on Rails / ActiveRecord
This will let you get one record for each unique value in your chosen column that matches the other query conditions:
MyModel.where(:some_col => value).select("DISTINCT ON (unique_col) *")
I prefer DISTINCT ON because I can still get all the other column values in the row. DISTINCT alone will only return the value of that specific column.
After often receiving the error myself I realised that Rails (I am using rails 4) automatically adds an 'order by id' at the end of your grouping query. This often results in the error above. So make sure you append your own .order(:group_by_column) at the end of your Rails query. Hence you will have something like this:
#problems = Problem.select('problems.username, sum(problems.weight) as weight_sum').group('problems.username').order('problems.username')
#myestate1 = Estate.where(:Mgmt => current_user.Company)
#myestate = #myestate1.select("DISTINCT(user_id)")
this is what I did.