Thread: Problem inserting composite type values

Hi all --

(huge apologies if this is a duplicate post -- I sent from an 
unsubscribed email account before...)

I have a problem trying to INSERT INTO a table by selecting from a 
function that returns a composite type. (I'm running version 8.1.4, FYI)

Basically, I have two tables. I want to retrieve rows from one table and 
store them into the other. The schema of the two tables is not the same, 
so I use a conversion function (written in plperl) that takes a row from 
the start table and returns a row from the end table. However, I can't 
get the insert working.

Here's a simplified example of my real system (must have plperl 
installed to try it):

---------------------------------------
-- Read rows from here...
CREATE TABLE startTable ( intVal integer, textVal text );

-- ...and store as rows in here
CREATE TABLE endTable ( intVal integer, newVal1 integer, newVal2 integer);

-- Some test data for the startTable
INSERT INTO startTable VALUES ( 1, '10:11');
INSERT INTO startTable VALUES ( 2, '20:25');
INSERT INTO startTable VALUES ( 3, '30:38');

-- Note: Takes composite type as argument, and returns composite type.
-- This just converts a row of startTable into a row of endTable, splitting
-- the colon-delimited integers from textVal into separate integers.
CREATE OR REPLACE FUNCTION convertStartToEnd(startTable) RETURNS 
endTable AS $$  my ($startTable) = @_;  my @newVals = split(/:/, $startTable->{"textval"});  my $result = {
"intval"=>$startTable->{"intval"},
 
"newval1"=>@newVals[0], "newval2"=>@newVals[1] };  return $result;
$$ LANGUAGE plperl;
---------------------------------------

Now, if I run the following SELECT, I get the results below it:

SELECT convertStartToEnd(st.*) FROM startTable st;

convertstarttoend
-------------------
(1,10,11)
(2,20,25)
(3,30,38)
(3 rows)

This seems OK. But when I try to INSERT the results of this select into 
the endTable, I get this error:

INSERT INTO endTable SELECT convertStartToEnd(st.*) FROM startTable st;

ERROR:  column "intval" is of type integer but expression is of type 
endtable
HINT:  You will need to rewrite or cast the expression

It's taking the entire row coming out of the function (e.g. "(3,30,38)") 
and tries to fit it all into just the first column, intVal. I'm 
obviously doing something wrong. Is there some way to format the INSERT 
so that I can get full rows inserted, with the individual columns 
separated out properly (e.g. intVal=3, newVal1=30, newVal2=38)?

I'm still pretty new to all this, so it could be something simple.

Thanks for reading.

Kind Regards,
Chris Dunworth

On Fri, 1 Dec 2006, Chris Dunworth wrote:

> Hi all --
>
> (huge apologies if this is a duplicate post -- I sent from an
> unsubscribed email account before...)
>
> I have a problem trying to INSERT INTO a table by selecting from a
> function that returns a composite type. (I'm running version 8.1.4, FYI)
>
> Basically, I have two tables. I want to retrieve rows from one table and
> store them into the other. The schema of the two tables is not the same,
> so I use a conversion function (written in plperl) that takes a row from
> the start table and returns a row from the end table. However, I can't
> get the insert working.
>
> Here's a simplified example of my real system (must have plperl
> installed to try it):
>
> ---------------------------------------
> -- Read rows from here...
> CREATE TABLE startTable ( intVal integer, textVal text );
>
> -- ...and store as rows in here
> CREATE TABLE endTable ( intVal integer, newVal1 integer, newVal2 integer);
>
> -- Some test data for the startTable
> INSERT INTO startTable VALUES ( 1, '10:11');
> INSERT INTO startTable VALUES ( 2, '20:25');
> INSERT INTO startTable VALUES ( 3, '30:38');
>
> -- Note: Takes composite type as argument, and returns composite type.
> -- This just converts a row of startTable into a row of endTable, splitting
> -- the colon-delimited integers from textVal into separate integers.
> CREATE OR REPLACE FUNCTION convertStartToEnd(startTable) RETURNS
> endTable AS $$
>    my ($startTable) = @_;
>    my @newVals = split(/:/, $startTable->{"textval"});
>    my $result = { "intval"=>$startTable->{"intval"},
> "newval1"=>@newVals[0], "newval2"=>@newVals[1] };
>    return $result;
> $$ LANGUAGE plperl;
> ---------------------------------------
>
> Now, if I run the following SELECT, I get the results below it:
>
> SELECT convertStartToEnd(st.*) FROM startTable st;
>
> convertstarttoend
> -------------------
> (1,10,11)
> (2,20,25)
> (3,30,38)
> (3 rows)
>
> This seems OK. But when I try to INSERT the results of this select into
> the endTable, I get this error:
>
> INSERT INTO endTable SELECT convertStartToEnd(st.*) FROM startTable st;


I think you'd need something likeINSERT INTO endTable SELECT (convertStartToEnd(st.*)).* FROM startTablest;
to make it break up the type into its components.

On 12/1/06, Stephan Szabo <sszabo@megazone.bigpanda.com> wrote:
INSERT INTO endTable SELECT * FROM (SELECT convertStartToEnd(st.*) FROM startTable)

that should work too

--
==================================================================
   Aaron Bono
   Aranya Software Technologies, Inc.
   http://www.aranya.com
   http://codeelixir.com
==================================================================

<br /> Stephan Szabo wrote: <blockquote cite="mid20061201155044.H8888@megazone.bigpanda.com" type="cite"><pre
wrap="">OnFri, 1 Dec 2006, Chris Dunworth wrote:
 
 </pre><blockquote type="cite"><pre wrap="">Hi all --

(huge apologies if this is a duplicate post -- I sent from an
unsubscribed email account before...)

I have a problem trying to INSERT INTO a table by selecting from a
function that returns a composite type. (I'm running version 8.1.4, FYI)

Basically, I have two tables. I want to retrieve rows from one table and
store them into the other. The schema of the two tables is not the same,
so I use a conversion function (written in plperl) that takes a row from
the start table and returns a row from the end table. However, I can't
get the insert working.

Here's a simplified example of my real system (must have plperl
installed to try it):

---------------------------------------
-- Read rows from here...
CREATE TABLE startTable ( intVal integer, textVal text );

-- ...and store as rows in here
CREATE TABLE endTable ( intVal integer, newVal1 integer, newVal2 integer);

-- Some test data for the startTable
INSERT INTO startTable VALUES ( 1, '10:11');
INSERT INTO startTable VALUES ( 2, '20:25');
INSERT INTO startTable VALUES ( 3, '30:38');

-- Note: Takes composite type as argument, and returns composite type.
-- This just converts a row of startTable into a row of endTable, splitting
-- the colon-delimited integers from textVal into separate integers.
CREATE OR REPLACE FUNCTION convertStartToEnd(startTable) RETURNS
endTable AS $$  my ($startTable) = @_;  my @newVals = split(/:/, $startTable->{"textval"});  my $result = {
"intval"=>$startTable->{"intval"},
"newval1"=>@newVals[0], "newval2"=>@newVals[1] };  return $result;
$$ LANGUAGE plperl;
---------------------------------------

Now, if I run the following SELECT, I get the results below it:

SELECT convertStartToEnd(st.*) FROM startTable st;

convertstarttoend
-------------------
(1,10,11)
(2,20,25)
(3,30,38)
(3 rows)

This seems OK. But when I try to INSERT the results of this select into
the endTable, I get this error:

INSERT INTO endTable SELECT convertStartToEnd(st.*) FROM startTable st;   </pre></blockquote><pre wrap="">

I think you'd need something likeINSERT INTO endTable SELECT (convertStartToEnd(st.*)).* FROM startTablest;
to make it break up the type into its components.
 </pre></blockquote><br /> Yes! That was exactly it. I thought it might have been something simple.<br /><br /> Thanks,
Stephan!<br/><br /> -Chris<br /><br /> 

Aaron Bono wrote:

On 12/1/06, Stephan Szabo <sszabo@megazone.bigpanda.com> wrote:

On Fri, 1 Dec 2006, Chris Dunworth wrote:

> Hi all --
>
> (huge apologies if this is a duplicate post -- I sent from an
> unsubscribed email account before...)
>
> I have a problem trying to INSERT INTO a table by selecting from a
> function that returns a composite type. (I'm running version 8.1.4, FYI)
>
> Basically, I have two tables. I want to retrieve rows from one table and
> store them into the other. The schema of the two tables is not the same,
> so I use a conversion function (written in plperl) that takes a row from
> the start table and returns a row from the end table. However, I can't
> get the insert working.
>
> Here's a simplified example of my real system (must have plperl
> installed to try it):
>
> ---------------------------------------
> -- Read rows from here...
> CREATE TABLE startTable ( intVal integer, textVal text );
>
> -- ...and store as rows in here
> CREATE TABLE endTable ( intVal integer, newVal1 integer, newVal2 integer);
>
> -- Some test data for the startTable
> INSERT INTO startTable VALUES ( 1, '10:11');
> INSERT INTO startTable VALUES ( 2, '20:25');
> INSERT INTO startTable VALUES ( 3, '30:38');
>
> -- Note: Takes composite type as argument, and returns composite type.
> -- This just converts a row of startTable into a row of endTable, splitting
> -- the colon-delimited integers from textVal into separate integers.
> CREATE OR REPLACE FUNCTION convertStartToEnd(startTable) RETURNS
> endTable AS $$
>    my ($startTable) = @_;
>    my @newVals = split(/:/, $startTable->{"textval"});
>    my $result = { "intval"=>$startTable->{"intval"},
> "newval1"=>@newVals[0], "newval2"=>@newVals[1] };
>    return $result;
> $$ LANGUAGE plperl;
> ---------------------------------------
>
> Now, if I run the following SELECT, I get the results below it:
>
> SELECT convertStartToEnd(st.*) FROM startTable st;
>
> convertstarttoend
> -------------------
> (1,10,11)
> (2,20,25)
> (3,30,38)
> (3 rows)
>
> This seems OK. But when I try to INSERT the results of this select into
> the endTable, I get this error:
>
> INSERT INTO endTable SELECT convertStartToEnd(st.*) FROM startTable st;


I think you'd need something like
INSERT INTO endTable SELECT (convertStartToEnd(st.*)).* FROM startTable
st;
to make it break up the type into its components.

INSERT INTO endTable SELECT * FROM (SELECT convertStartToEnd(st.*) FROM startTable)

that should work too

Hi Aaron --

I had actually tried your approach earlier, or something very similar:

INSERT INTO endTable SELECT et.* FROM (SELECT convertStartToEnd(st.*) FROM startTable st) AS et;

Which is basically the same as you suggest, plus an alias ("et") for the subquery that postgresql was asking for. But it gave the same type mismatch result as I posted about.

Turns out Stephan's suggestion did the trick.

Cheers,
Chris

On 12/1/06, Chris Dunworth <cdunworth@earthcomber.com> wrote:
Good to know.  I will keep that in mind if I come across that again in the future.

-Aaron

--
==================================================================
   Aaron Bono
   Aranya Software Technologies, Inc.
   http://www.aranya.com
   http://codeelixir.com
==================================================================