Re: Dynamic query execution using array - Mailing list pgsql-general

From ChoonSoo Park
Subject Re: Dynamic query execution using array
Date
Msg-id CACgbiFsjOcXNVNx1GuLAe2C0LY2AKd1ikt9+yiBdh7Q6sL1feQ@mail.gmail.com
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In response to Re: Dynamic query execution using array  (Pavel Stehule <pavel.stehule@gmail.com>)
Responses Re: Dynamic query execution using array  (Pavel Stehule <pavel.stehule@gmail.com>)
List pgsql-general
It works! 

One more question. 
Do I have to use CAST for parameter value holder?

employee table's dept_id and salary columns are integer types. 

RETURN QUERY EXECUTE 'SELECT * FROM employee WHERE dept_id = $1[1] and salary <= $1[2]' using tmpArrayValues;

When I use text array, it complains:
ERROR:  operator does not exist: integer = text

So I have to match the type using CAST.
RETURN QUERY EXECUTE 'SELECT * FROM employee WHERE dept_id = CAST($1[1] as integer) and salary <= CAST($1[2] as integer)' using tmpArrayValues;

Looks like 
Other ways to avoid using CAST?

Best Regards,
Choon Park

On Fri, Jul 6, 2012 at 11:45 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
Hello

2012/7/6 ChoonSoo Park <luispark@gmail.com>:
> Inside a function, I can execute dynamic query like this
>
>       dept_id = 1;
>       salary = 50000;
>       RETURN QUERY EXECUTE 'SELECT * FROM employee WHERE dept_id = $1 and
> salary >= $2' using dept_id, salary;
>
> When the query condition is dynamically generated and number of parameters
> is also dynamic,
>
> DECLARE
>       tmpArray   text[];
>       query text;
> BEGIN
>       -- inputParameter will have the whole parameter list separated by
> comma.
>       tmpArray = string_to_array(inputParam, ',');
>
>       -- Let's assume the query condition is dynamically constructed from
> somewhere else.
>       query = 'select * FROM employee WHERE ' || dynamicQueryFunction(...);
>       RETURN QUERY EXECUTE query using tmpArray;
> END
>
> I know above one will fail to execute.
> Of course, if I construct dynamic query using one of (quote_nullable,
> quote_literal, format), I can execute it.
>
> Is there any other way to achieve dynamic query execution using array value?

it can work, but you have to use array access notation

EXECUTE 'SELECT .. WHERE a = $1[1] AND b = $1[2]' USING ARRAY[10,20]

Regards

Pavel

>
> Thanks in advance,
> Choon Park

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