PL/pgSQL Array of Rows | 易学教程

问题

Is the following possible?
I want to have a procedure written in PL/pgSQL that takes as parameter something like "collection of row", I mean I need to pass to function a dictionary-like structure:

Pseudocode:

function_name({key1:val1,key2:val2, key3:val3 [, ...] })

回答1:

With modern day PostgreSQL you can simplify such a function.
Test setup:

CREATE TABLE tbl1 (id int, value text);

No need to create a type explicitly in this case (if the type is based on a table row), it is created for every table implicitly.
Function:

CREATE FUNCTION f_insert_rows_into_tbl1(tbl1[])
  RETURNS VOID AS
$BODY$
    INSERT INTO tbl1 (id,value)
    SELECT (a).*
    FROM   (SELECT unnest($1) AS a) x;
$BODY$ LANGUAGE sql;

Call:

SELECT f_insert_rows_into_tbl1('{"(1,foo)","(2,bar)"}');

Note the input syntax for an array of rows!

回答2:

Visit this site http://postgres.cz/wiki/PostgreSQL_SQL_Tricks and search for Array to table. There may be other ways on newer versions, but I had this in my bookmarks from awhile back. Source from website:

CREATE OR REPLACE FUNCTION unpack(anyarray)
RETURNS SETOF anyelement AS $$ 
SELECT $1[i] 
   FROM generate_series(array_lower($1,1), 
                        array_upper($1,1)) g(i);
$$ LANGUAGE sql STRICT IMMUTABLE;

select unpack(array['a','b','c']);

回答3:

I think you can use a composite type and array argument. Something like (untested):

create type keyvalue as (
  key text,
  value text
);

create function function_name(keyvalue[]) returns null as $$
declare
  keyvalue x;
begin
  foreach x in array $1 loop
    insert into tablename(key,value) values (x.key, x.value);
  end loop
end;
$$ language plpgsql;

This will not be a true dictionary, as you can add duplicate keyvalues and keyvalues with the same key and different value to this array. But just for passing arguments to a function it should be enough.

Using unpack() mentioned by JustBob will allow to not use a loop, which is not very SQL-y, but treat this array as a set.

来源：https://stackoverflow.com/questions/9640087/pl-pgsql-array-of-rows

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