whats the STUFF equivalent in netezza, I am trying to do rows to column concatenation. I tried the GROUP_CONCAT()/ String_AGG as mentioned in the other question but i am not able to use both of them.
I've never used STUFF before, but looking at the description, there is not a native Netezza function that is its equivalent. However, it seems a simple thing to recreate with SUBSTR. Since I don't really use STUFF, take this with a grain of salt, but give it a try.
If we take an example of using STUFF:
SELECT STUFF('abcdef', 2, 3, 'ijklmn');
---------
aijklmnef
(1 row(s) affected)
If I dummy up the values and STUFF parameters into a subselect for demonstration purposes, here's how you can do it with SUBSTR.
SELECT
substr(orig_string ,0,start_pos)
|| replace_string ||
substr(orig_string,start_pos+del_length, LENGTH(orig_string)) new_string,
orig_string , replace_string
FROM
( SELECT
'abcdef' orig_string ,
2 start_pos ,
3 del_length ,
'ijklmn' replace_string ) foo
;
NEW_STRING | ORIG_STRING | REPLACE_STRING
------------+-------------+----------------
aijklmnef | abcdef | ijklmn
(1 row)
You can use GROUP_CONCAT to achieve similar results as with STUFF. The GROUP_CONCAT function must installed from nzlua examples directory on the Netezza Linux environment.
export NZ_PASSWORD='YOURADMINPASSWORD'
cd /nz/extensions/nz/nzlua/examples
../bin/nzl group_concat.nzl
After this group_concat is available in Netezza SYSTEM database. As ADMIN you can execute these commands to make them easily available to all users in a database.
grant execute on system..group_concat(varchar(128)) to public; -- once
create synonym group_concat for system..group_concat; -- in every user database
Related
So, I have Hibernate 5.3.1 in a project which connects to different enginees (MySql, Oracle, PostgreSQL and MS SQL), so I can't use native queries.
Let's say I have 3 records in a table, which all of them have the same datetime, but I need to group them only by date (not time). For example, 2019-12-04;
I execute this query:
SELECT
CONCAT(year(tx.date_), month(tx.date_), day(tx.date_)),
iss.code,
COUNT(tx.id)
FROM
tx_ tx
JOIN
issuer_ iss
ON
tx.id_issuer = iss.id
GROUP BY
CONCAT(year(tx.date_), month(tx.date_), day(tx.date_)), iss.code
But, when I test it connected to SQL SERVER 2017, instead of return 20191204, it's returning 2035. In Oracle and MySQL is working fine.
Anyone has any idea why is this happen? I've tried different ways, like use + instead of CONCAT but the result is the same.
I've also tried to extract them for separate (without concat), and they have been returning correct. The problem is, I need to group them by the complete date.
And just for the record, the field is declared as datetime2 in DDBB
How about simply adding them, instead of using CONCAT.
(year(tx.date_)*10000 + month(tx.date_)*100 + day(tx.date_)*1) AS datenum
Thus, try this:
SELECT
CAST((year(tx.date_)*10000 + month(tx.date_)*100 + day(tx.date_)*1) AS string) AS datenum,
iss.code
FROM tx_ tx
JOIN issuer_ iss
ON tx.id_issuer = iss.id
GROUP BY year(tx.date_), month(tx.date_), day(tx.date_), iss.code
Thanks for the hint Gert Arnold gave me. I just didn't realize that the query was adding like if they were numbers in MSSQL.
Finally, I manage to make it work in the 4 RDBMS casting to string first
SELECT
CONCAT(CAST(year(tx.date_) AS string), CAST(month(tx.date_) AS string), CAST(day(tx.date_) AS string)),
iss.code
FROM
tx_ tx
JOIN
issuer_ iss
ON
tx.id_issuer = iss.id
GROUP BY
CONCAT(year(tx.date_), month(tx.date_), day(tx.date_)), iss.code
I tried also casting to TEXT, but it throws exception in MySQL
Why use concat() to begin with?
Assuming Hibernate takes care of converting the non-standard year(), month() and day() functions, then the following should work on any DBMS
SELECT year(tx.date_), month(tx.date_), day(tx.date_), iss.code
FROM tx_ tx
JOIN issuer_ iss ON tx.id_issuer = iss.id
GROUP BY year(tx.date_), month(tx.date_), day(tx.date_), iss.code
I need to make hierarchical queries, and I need to get the results of CONNECT_BY_ISCYCLE and CONNECT_BY_ISLEAF, but these features are supported in Oracle not in Snowflake.
What are the alternative ways to implement the functionalities of CONNECT_BY_ISCYCLE and CONNECT_BY_ISLEAF in snowflake without using them as these keywords are not supported there?
Wonder if you have taken a look at the following Snowflake features?
https://docs.snowflake.net/manuals/user-guide/queries-hierarchical.html#using-connect-by-or-recursive-ctes-to-query-hierarchical-data
Yes I took a look there. I also took a look at https://docs.snowflake.net/manuals/sql-reference/constructs/connect-by.html where it clearly says that these features are not supported in Snowflake.
I was trying below code block to find an alternative but facing varieties of error in snowflake.
person_vertex as (
select
emp_number,
user_id
from person
),
person_edges as (
select
supervisor_emp_number,
emp_number
from person
where supervisor_emp_number is not null
),
select
pv.emp_number emp_id_pk,
level,
CONNECT_BY_ROOT pv.emp_number AS root,
concat(SYS_CONNECT_BY_PATH(pv.emp_number,':'),':') as path,
-- CONNECT_BY_ISCYCLE AS iscyclic, ------------------- no idea how to implement this
-- CONNECT_BY_ISLEAF as isleaf ------------------- i tried below block, but it is not working
case
when (pe.supervisor_emp_number in (select emp_number from pv)) then 0
else 1
end AS isleaf
from person_vertex pv
left join person_edges pe on pv.emp_number = pe.emp_number
connect by prior A.emp_number = A.supervisor_emp_number
start with A.supervisor_emp_number is null
Any help with this block is really appreciated.
Thanks.
enter code here
I can use below code get int result in C#
new DataTable().Compute("1 * 2 / 2 + 3", string.Empty);//result:4
How can I do it in SQL Server? I expect convert and operation string to int.
My solution is CLR , but there is no any original solution?
Thanks.
There are a couple things you need to do.
Create the assembly with the CLR logic you already have.
On the SQL Server side, create a User-Defined Function that calls the assembly.
This is an example of what the UDF would look like from the documentation:
CREATE ASSEMBLY FirstUdf FROM 'FirstUdf.dll';
GO
CREATE FUNCTION CountSalesOrderHeader() RETURNS INT
AS EXTERNAL NAME FirstUdf.T.ReturnOrderCount;
GO
SELECT dbo.CountSalesOrderHeader();
GO
Just write like it is
select 1 * 2 / 2 + 3
I'm working on a project that has a search engine. AS we know in MS ACCESS we could use "*" in Queries under Criteria field to retrieve all records.
In SQL Server I need the same technique. I have tried different LIKE with WHERE Clauses. But I still didn't get the exact result I want.
In this project I have 3 textboxes (Category, Item, Location). If the user leaves any of them empty. I want to retrieve all the records.
I need something like this:
string t1,t2,t3;
if(!String.IsNullOrEmpty(txtCategory.Text))
t1=txtCategory.Text;
else
t1="*";
if(!String.IsNullOrEmpty(txtItem.Text))
t2=txtItem.Text;
else
t2="*"
if(!String.IsNullOrEmpty(txtLoc.Text))
t2=txtLoc.Text;
else
t3="*";
-
-
-
// in a function i have this :
SELECT * FROM Table_Items WHERE Category='"+t1+"' AND Item='"+t2+"' AND Location='"+t3+"'"
in ms sql server you can use the same technique but instead of * you should use %.
for examples:
%: means any
a%: all strings that start with a
%z: all strings that end with z
SO, your code should look like something as below:
// codes here
t3="%";
WHERE ColumnName LIKE t3
or
Where ColumnName LIKE '%'
I hope that will help you.
Change your * to the %
... Where Category Like "'+t1+"' and Item Like '"+t2+"' ...
Here's my situation. I have a table with a bunch of URLs and crawl
dates associated with them. When my program processes a URL, I want
to INSERT a new row with a crawl date. If the URL already exists, I
want to update the crawl date to the current datetime. With MS SQL or
Oracle I'd probably use a MERGE command for this. With mySQL I'd
probably use the ON DUPLICATE KEY UPDATE syntax.
I could do multiple queries in my program, which may or may not be
thread safe. I could write a SQL function which has various IF...ELSE
logic. However, for the sake of trying out Postgres features I've
never used before, I'm thinking about creating an INSERT rule -
something like this:
CREATE RULE Pages_Upsert AS ON INSERT TO Pages
WHERE EXISTS (SELECT 1 from Pages P where NEW.Url = P.Url)
DO INSTEAD
UPDATE Pages SET LastCrawled = NOW(), Html = NEW.Html WHERE Url = NEW.Url;
This seems to actually work great. It probably loses some points on
the "code readability" standpoint, as someone looking at my code for
the first time would have to magically know about this rule, but I
guess that could be solved with good code commenting and
documentation.
Are there any other drawbacks to this idea, or maybe a "your idea
sucks, you should do it /this/ way instead" comment? I'm on PG 9.0 if
that matters.
UPDATE: Query plan since someone wanted it :)
"Insert (cost=2.79..2.81 rows=1 width=0)"
" InitPlan 1 (returns $0)"
" -> Seq Scan on pages p (cost=0.00..2.79 rows=1 width=0)"
" Filter: ('http://www.foo.com'::text = lower((url)::text))"
" -> Result (cost=0.00..0.01 rows=1 width=0)"
" One-Time Filter: ($0 IS NOT TRUE)"
""
"Update (cost=2.79..5.46 rows=1 width=111)"
" InitPlan 1 (returns $0)"
" -> Seq Scan on pages p (cost=0.00..2.79 rows=1 width=0)"
" Filter: ('http://www.foo.com'::text = lower((url)::text))"
" -> Result (cost=0.00..2.67 rows=1 width=111)"
" One-Time Filter: $0"
" -> Seq Scan on pages (cost=0.00..2.66 rows=1 width=111)"
" Filter: ((url)::text = 'http://www.foo.com'::text)"
Ok, I managed to create a testcase. The result is that the update part is always executed, even on a fresh insert. COPY seems to bypass the rule system.
[For clarity I have put this into a separate reply]
DROP TABLE pages CASCADE;
CREATE TABLE pages
( url VARCHAR NOT NULL PRIMARY KEY
, html VARCHAR
, last TIMESTAMP
);
INSERT INTO pages(url,html,last) VALUES ('www.example.com://page1' , 'meuk1' , '2001-09-18 23:30:00'::timestamp );
CREATE RULE Pages_Upsert AS ON INSERT TO pages
WHERE EXISTS (SELECT 1 from pages P where NEW.url = P.url)
DO INSTEAD (
UPDATE pages SET html=new.html , last = NOW() WHERE url = NEW.url
);
INSERT INTO pages(url,html,last) VALUES ('www.example.com://page2' , 'meuk2' , '2002-09-18 23:30:00':: timestamp );
INSERT INTO pages(url,html,last) VALUES ('www.example.com://page3' , 'meuk3' , '2003-09-18 23:30:00':: timestamp );
INSERT INTO pages(url,html,last) SELECT pp.url || '/added'::text, pp.html || '.html'::text , pp.last + interval '20 years' FROM pages pp;
COPY pages(url,html,last) FROM STDIN;
www.example.com://pageX stdin 2000-09-18 23:30:00
\.
SELECT * FROM pages;
The result:
url | html | last
-------------------------------+------------+----------------------------
www.example.com://page1 | meuk1 | 2001-09-18 23:30:00
www.example.com://page2 | meuk2 | 2011-09-18 23:48:30.775373
www.example.com://page3 | meuk3 | 2011-09-18 23:48:30.783758
www.example.com://page1/added | meuk1.html | 2011-09-18 23:48:30.792097
www.example.com://page2/added | meuk2.html | 2011-09-18 23:48:30.792097
www.example.com://page3/added | meuk3.html | 2011-09-18 23:48:30.792097
www.example.com://pageX | stdin | 2000-09-18 23:30:00
(7 rows)
UPDATE: Just to prove it can be done:
INSERT INTO pages(url,html,last) VALUES ('www.example.com://page1' , 'meuk1' , '2001-09-18 23:30:00'::timestamp );
CREATE VIEW vpages AS (SELECT * from pages);
CREATE RULE Pages_Upsert AS ON INSERT TO vpages
DO INSTEAD (
UPDATE pages p0
SET html=NEW.html , last = NOW() WHERE p0.url = NEW.url
;
INSERT INTO pages (url,html,last)
SELECT NEW.url, NEW.html, NEW.last
WHERE NOT EXISTS ( SELECT * FROM pages p1 WHERE p1.url = NEW.url)
);
CREATE RULE Pages_Indate AS ON UPDATE TO vpages
DO INSTEAD (
INSERT INTO pages (url,html,last)
SELECT NEW.url, NEW.html, NEW.last
WHERE NOT EXISTS ( SELECT * FROM pages p1 WHERE p1.url = OLD.url)
;
UPDATE pages p0
SET html=NEW.html , last = NEW.last WHERE p0.url = NEW.url
;
);
INSERT INTO vpages(url,html,last) VALUES ('www.example.com://page2' , 'meuk2' , '2002-09-18 23:30:00':: timestamp );
INSERT INTO vpages(url,html,last) VALUES ('www.example.com://page3' , 'meuk3' , '2003-09-18 23:30:00':: timestamp );
INSERT INTO vpages(url,html,last) SELECT pp.url || '/added'::text, pp.html || '.html'::text , pp.last + interval '20 years' FROM vpages pp;
UPDATE vpages SET last = last + interval '-10 years' WHERE url = 'www.example.com://page1' ;
-- Copy does NOT work on views
-- COPY vpages(url,html,last) FROM STDIN;
-- www.example.com://pageX stdin 2000-09-18 23:30:00
-- \.
SELECT * FROM vpages;
Result:
INSERT 0 1
INSERT 0 1
INSERT 0 3
UPDATE 1
url | html | last
-------------------------------+------------+---------------------
www.example.com://page2 | meuk2 | 2002-09-18 23:30:00
www.example.com://page3 | meuk3 | 2003-09-18 23:30:00
www.example.com://page1/added | meuk1.html | 2021-09-18 23:30:00
www.example.com://page2/added | meuk2.html | 2022-09-18 23:30:00
www.example.com://page3/added | meuk3.html | 2023-09-18 23:30:00
www.example.com://page1 | meuk1 | 1991-09-18 23:30:00
(6 rows)
The view is necessary to prevent the rewrite system to go into recursion.
Construction of a DELETE rule is left as an exercise to the reader.
Some good points from someone who should know it or be very near to someone like that ;-)
What are PostgreSQL RULEs good for?
Short story:
Do the rules work well with SERIAL and BIGSERIAL ?
Do the rules work well with the RETURNING clauses of INSERT and UPDATE ?
Do the rules work well with stuff like random()?
All these things boils down to the fact, that the rule system is not row driven but transforms your statements in a way you never imagine.
Do yourself and your team mates a favour and stop using roles for things like that.
Edit: Your problem is well discussed in the PostgreSQL community. Search keywords are: MERGE, UPSERT.
I don't know if this gets too subjective but what I think about your solution is: It's all about semantics. When I do an insert, I expect an insert and not some fancy logic that maybe does an insert but maybe not. Indeed that's what functions are for.
At first I'd try checking for the URL in your program and then choosing whether to insert or update. If that turned out to be too slow, I'd use a function. If you name it like insert_or_update_url, you automatically get some documentation for free. The rewrite rule requires you to have some implicit knowledge and I generally try to avoid that.
On the plus side: If someone copies the data but forgets rules and functions, your solution might break silently (but that may depend on other constraints), but a missing function goes down screaming. Don't get me wrong, I think your solution is very creative and smart. Just a bit too obscure for my taste.
There's an example of implementing upsert / merge using simple function in Postgres documentation.
Never use rules — they're evil.
You cannot refer to other tables than old an new in the rule qualification.
You should instead do this in the rule body.
This is all because the rule is just a way to inform the rewrite system about what transformations it should and should not perform. Rules are not triggers, executing for every row, but they give the query planner a fine massage and ask it nicely to rewrite the plan.
From the docs:
What is a rule qualification? It is a restriction that tells when the actions of the rule should be done and when not. This qualification can only reference the pseudorelations NEW and/or OLD, which basically represent the relation that was given as object (but with a special meaning).