Importing data from CSV into a table with array and composite types

Hi

2018-05-18 10:37 GMT+02:00 a <372660931@qq.com>:

Hi:

I would like to import data from a csv table. But the table that is going
to be inserted is constructed with arrays and composite types, also with
array of composite.

I have tried many ways of inserting but fail. Can anyone help? Thank you
so much.

create type p as (a int, b int);
create table f(pv p[], c int);
insert into f values(array[(10,20),(30,40)]::p[], 1000);
insert into f values(array[(1,20),(3,40)]::p[], -1000);

postgres=# copy f to stdout csv;
"{""(10,20)"",""(30,40)""}",1000
"{""(1,20)"",""(3,40)""}",-1000
Time: 0,391 ms

So you have to respect this format. CSV doesn't know a arrays, doesn't know
composite - so these values are passed as string

Regards

Pavel

Thank you so much. BTW, may I ask one more question that, how should I select every first element of the array??

I know that "select p[:] from f" will print all element of the p array, but I probably would want to present result as "select p[:].a from f", but the statement does not work.

May I as the correct statement of displaying all first element of the composite type in an array??

Thank you!

Shore

------------------ Original message ------------------
From: "Pavel Stehule";
Sendtime: Friday, May 18, 2018 5:46 PM
To: "a"<372660931@qq.com>;
Cc: "pgsql-general";
Subject: Re: Importing data from CSV into a table with array and composite types

Hi

2018-05-18 10:37 GMT+02:00 a <372660931@qq.com>:
Hi:

I would like to import data from a csv table. But the table that is going to be inserted is constructed with arrays and composite types, also with array of composite.

I have tried many ways of inserting but fail. Can anyone help? Thank you so much.

create type p as (a int, b int);
create table f(pv p[], c int);
insert into f values(array[(10,20),(30,40)]::p[], 1000);
insert into f values(array[(1,20),(3,40)]::p[], -1000);

postgres=# copy f to stdout csv;
"{""(10,20)"",""(30,40)""}",1000
"{""(1,20)"",""(3,40)""}",-1000
Time: 0,391 ms

So you have to respect this format. CSV doesn't know a arrays, doesn't know composite - so these values are passed as string

Regards

Pavel

2018-05-20 7:36 GMT+02:00 a <372660931@qq.com>:

Thank you so much. BTW, may I ask one more question that, how should I
select every first element of the array??

I know that "select p[:] from f" will print all element of the p array,
but I probably would want to present result as "select p[:].a from f", but
the statement does not work.

May I as the correct statement of displaying all first element of the
composite type in an array??

it is not easy - for example, that I sent you can write a query

postgres=# select array_agg(a) from f, unnest(pv) where f.c = 1000;
┌───────────┐
│ array_agg │
╞═══════════╡
│ {10,30} │
└───────────┘
(1 row)