Thread: variable value in array_to_string
Hi
Is there anyway I can pass a variable in the array_to_string function ?
CREATE OR REPLACE FUNCTION test1 () RETURNS void AS $$
DECLARE
foo text;
foo1 text;
begin
execute
'select ARRAY( SELECT d.COLUMN_NAME::text from information_schema.constraint_table_usage c,
information_schema.key_column_usaged '
||
'where c.constraint_name=d.constraint_name and c.table_name=d.table_name and c.table_schema='
||
quote_literal(‘myschema')
||
' and c.table_schema=d.table_schema and c.constraint_name like '
||
quote_literal('%_pkey%')
||
') ' into foo;
raise notice '%', foo;
foo1 :=ARRAY_TO_STRING(foo, ', ');
raise notice '%', foo1;
END;
$$ LANGUAGE plpgsql ;
The idea is that I want to slice and dice and not run the query x amount of times
Thank you
Armand
Hi
Is there anyway I can pass a variable in the array_to_string function ?
Yes, just like you can pass variables to any other function...
CREATE OR REPLACE FUNCTION test1 () RETURNS void AS $$DECLARE
foo text;
foo1 text;
begin
execute
'select ARRAY( SELECT d.COLUMN_NAME::text from information_schema.constraint_table_usage c, information_schema.key_column_ usage d '
||
'where c.constraint_name=d.constraint_name and c.table_name=d.table_name and c.table_schema='
||
quote_literal(‘myschema')
||
' and c.table_schema=d.table_schema and c.constraint_name like '
||
quote_literal('%_pkey%')
||
') ' into foo;
raise notice '%', foo;
foo1 :=ARRAY_TO_STRING(foo, ', ');
raise notice '%', foo1;
END;
$$ LANGUAGE plpgsql ;
The idea is that I want to slice and dice and not run the query x amount of times
I would suggest you learn to use the "format()" function, EXECUTE USING, and dollar quoting.
So, I copy-pasted your example and placed it into a DO block
The character before "myschema" came out as a back-tick instead of a single-quote.
array_to_string has the signature (text[], text) but you've defined foo as being just text. Changing that results in a query that executes - though given my system doesn't have conforming data I get no results.
David J.
My bad on the back tick. No idea why it turned that way
OK got that David.
The idea is that I have the pk columns in an array which I would like to manipulate from the array itself rather than running same query variations multiple times
For example I get in foo
{item_id,show_id}
And from here on I was looking to get say
a.item_id , a.show_id
and all sort of variations
Thanks for help
On Nov 21, 2016, at 4:26 PM, David G. Johnston <david.g.johnston@gmail.com> wrote:
Hi
Is there anyway I can pass a variable in the array_to_string function ?Yes, just like you can pass variables to any other function...
CREATE OR REPLACE FUNCTION test1 () RETURNS void AS $$DECLARE
foo text;
foo1 text;
begin
execute
'select ARRAY( SELECT d.COLUMN_NAME::text from information_schema.constraint_table_usage c, information_schema.key_column_ usage d '
||
'where c.constraint_name=d.constraint_name and c.table_name=d.table_name and c.table_schema='
||
quote_literal(‘myschema')
||
' and c.table_schema=d.table_schema and c.constraint_name like '
||
quote_literal('%_pkey%')
||
') ' into foo;
raise notice '%', foo;
foo1 :=ARRAY_TO_STRING(foo, ', ');
raise notice '%', foo1;
END;
$$ LANGUAGE plpgsql ;
The idea is that I want to slice and dice and not run the query x amount of timesI would suggest you learn to use the "format()" function, EXECUTE USING, and dollar quoting.So, I copy-pasted your example and placed it into a DO blockThe character before "myschema" came out as a back-tick instead of a single-quote.array_to_string has the signature (text[], text) but you've defined foo as being just text. Changing that results in a query that executes - though given my system doesn't have conforming data I get no results.David J.
Played with unnest but not much luck
NOTICE: {item_id,show_id}
NOTICE: item_id
It takes only the first array element in consideration
Ughhhh
On Nov 21, 2016, at 5:02 PM, Armand Pirvu (home) <armand.pirvu@gmail.com> wrote:
My bad on the back tick. No idea why it turned that wayOK got that David.The idea is that I have the pk columns in an array which I would like to manipulate from the array itself rather than running same query variations multiple timesFor example I get in foo{item_id,show_id}And from here on I was looking to get saya.item_id , a.show_idand all sort of variationsThanks for helpOn Nov 21, 2016, at 4:26 PM, David G. Johnston <david.g.johnston@gmail.com> wrote:Hi
Is there anyway I can pass a variable in the array_to_string function ?Yes, just like you can pass variables to any other function...
CREATE OR REPLACE FUNCTION test1 () RETURNS void AS $$DECLARE
foo text;
foo1 text;
begin
execute
'select ARRAY( SELECT d.COLUMN_NAME::text from information_schema.constraint_table_usage c, information_schema.key_column_ usage d '
||
'where c.constraint_name=d.constraint_name and c.table_name=d.table_name and c.table_schema='
||
quote_literal(‘myschema')
||
' and c.table_schema=d.table_schema and c.constraint_name like '
||
quote_literal('%_pkey%')
||
') ' into foo;
raise notice '%', foo;
foo1 :=ARRAY_TO_STRING(foo, ', ');
raise notice '%', foo1;
END;
$$ LANGUAGE plpgsql ;
The idea is that I want to slice and dice and not run the query x amount of timesI would suggest you learn to use the "format()" function, EXECUTE USING, and dollar quoting.So, I copy-pasted your example and placed it into a DO blockThe character before "myschema" came out as a back-tick instead of a single-quote.array_to_string has the signature (text[], text) but you've defined foo as being just text. Changing that results in a query that executes - though given my system doesn't have conforming data I get no results.David J.
Please don't top-post - it makes following the thread a lot harder.
On Mon, Nov 21, 2016 at 4:15 PM, Armand Pirvu (home) <armand.pirvu@gmail.com> wrote:
Played with unnest but not much luck
If you want help you will need to show your work - ideally with examples that can execute with meaningful data on an empty database.
The follow gives the expected results:
DO $$
DECLARE
foo text[];
foo1 text;
delim text := ',';
begin
foo := ARRAY['one','two']::text[];
foo1 := array_to_string(foo, delim);
RAISE NOTICE '%', foo1;
END;
$$;
NOTICE: one,two
David J.
1 - I added some new notes.
2 - That code I know and works fine. I used it in slightly different contexts in other projects
Here it is a case .
A table with two columns , data type is irrelevant
I have a need in which I may get a.col1,a.col2 and other variations
Point is yes I could build any variation re-running a slightly different way the query in the catalogs
But why hit 3 or 4 times when I could manipulate an array like below ? This code just came in my mind (and works)
CREATE OR REPLACE FUNCTION test1 () RETURNS void AS $$
DECLARE
var1 text[];
var2 text;
var3 text;
var4 text;
begin
execute
'select ARRAY( select column_name::text from information_schema.columns where table_name='
||
quote_literal('foo')
||')' into var1;
raise notice '%', var1;
select array_to_string(array(select 'a.'||unnest(var1)),',') into var4;
raise notice '%', var4;
END;
$$ LANGUAGE plpgsql ;
levregdb1=# select test1(); NOTICE: {col1,col2}
NOTICE: a.col1,a.col2
Note the a. being prepended to each of the array’s elements
3 - I appreciate the help. Keep in mind I am not a developer and this is a new venture for me. On the same token I am not an ignorant either . What irritates me is the TRUE lack in this case of explanations in the docs. I know another DBMS just as bad in the documentation area (worse in fact)
I turned to the community. And yes I know how to make cases since I worked support.
Frankly I am turning off since I sure as heck don’t like being patronized. Did not accept this (and never will) from my own mom let alone somebody else
My apologies for asking help. Will try not to do it again
Thanks and laters
On Nov 21, 2016, at 7:12 PM, David G. Johnston <david.g.johnston@gmail.com> wrote:
Please don't top-post - it makes following the thread a lot harder.On Mon, Nov 21, 2016 at 4:15 PM, Armand Pirvu (home) <armand.pirvu@gmail.com> wrote:Played with unnest but not much luckIf you want help you will need to show your work - ideally with examples that can execute with meaningful data on an empty database.The follow gives the expected results:DO $$DECLAREfoo text[];foo1 text;delim text := ',';beginfoo := ARRAY['one','two']::text[];foo1 := array_to_string(foo, delim);RAISE NOTICE '%', foo1;END;$$;NOTICE: one,twoDavid J.
For what its worth:
DO $$
DECLARE
vresult text;
begin
EXECUTE $qry$
WITH cols (c) AS ( VALUES ('col1'),('col2') )
SELECT string_agg('a.' || cols.c, ',')
FROM cols
WHERE 'foo' = $1
$qry$
USING 'foo'
INTO vresult;
RAISE NOTICE '%', vresult;
END;
$$;
I still haven't actually figured out what your question is which is maybe why I'm coming across as patronizing. And while I get that what you wrote is technically correct its using capabilities that have since be superseded by more readable and less error-prone facilities.
The docs do explain this material in terms of technical capabilities. For better and worse it doesn't always go to great lengths (or keeps up with changing times) to describe best practices or how multiple pieces fit together.
I'm also thinking that your original question is more accurately worded: Is there anyway I can [use an expression] in the array_to_string function
I'm not nit-picking here - the word variable when you writing a pl/pgsql language function has a very specific meaning which is not <'a.' || column_name>
In both cases the answer is a simple yes. Sorry for causing pain by offering up more information than requested. Its bad habit of mine - trying to provide related information when presented with a question.
David J.