Thread: how postgresql passes the parameter to the function. syntax error near or at "$1".

I want to create a function which use to truncate the table specified by the
caller. I very confused how postgresql pass this parameter into the function
:

as a superuser to execute :
1)
create or replace function d() returns void as $$
analyze;
$$ language sql;


----- this works when i issue select d()

2) this doesn't work

create or replace function v(text) returns void as $$
analyze $1;
$$ language sql;

 why???? and how to correct it?


I tried another function for insert

1) this works.

create or replace function insert_f(integer) returns void as $$
insert into t1 values($1);
$$ language sql;

----this works when i issue select insert_f(20);

2) this doesn't work.

create or replace function insert_f(text,integer) returns void as $$
insert into $1 values($2);
$$ language sql;

---- it failed to create the function and give me error : syntax error at or
near "$1".

Please help.

Thanks.

Regards.

Grace



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Hello

parameter - $n cannot be used on table name or column name position.
Some statements - DROP, VACUUM, ANALYZE doesn't support parameters
ever.

You have to use dynamic SQL in these cases.

CREATE OR REPLACE FUNCTION foo(tablename text, value text)
RETURNS void AS $$
BEGIN
  EXECUTE 'insert into ' || quote_ident(tablename) || ' VALUES($1)' USING value;
END;
$$ LANGUAGE plpgsql

Regards

Pavel Stehule

2012/3/28 leaf_yxj <leaf_yxj@163.com>:
> I want to create a function which use to truncate the table specified by the
> caller. I very confused how postgresql pass this parameter into the function
> :
>
> as a superuser to execute :
> 1)
> create or replace function d() returns void as $$
> analyze;
> $$ language sql;
>
>
> ----- this works when i issue select d()
>
> 2) this doesn't work
>
> create or replace function v(text) returns void as $$
> analyze $1;
> $$ language sql;
>
>  why???? and how to correct it?
>
>
> I tried another function for insert
>
> 1) this works.
>
> create or replace function insert_f(integer) returns void as $$
> insert into t1 values($1);
> $$ language sql;
>
> ----this works when i issue select insert_f(20);
>
> 2) this doesn't work.
>
> create or replace function insert_f(text,integer) returns void as $$
> insert into $1 values($2);
> $$ language sql;
>
> ---- it failed to create the function and give me error : syntax error at or
> near "$1".
>
> Please help.
>
> Thanks.
>
> Regards.
>
> Grace
>
>
>
> --
> View this message in context:
http://postgresql.1045698.n5.nabble.com/how-postgresql-passes-the-parameter-to-the-function-syntax-error-near-or-at-1-tp5601053p5601053.html
> Sent from the PostgreSQL - general mailing list archive at Nabble.com.
>
> --
> Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-general