PL/PostgreSQL how to convert a variable into a table name

问题

So I have a function in PostgreSQL that dynamically selects columns from a dynamic table. I got this solution from this post and it works great other than one thing.

This is inside of a file that is connected to a Node server, and so the $1 and $2 in the second SELECT * FROM represent values passed from there. The issue right now is that I am getting a syntax error that I don't understand (I am newer to SQL so that may be why).

$2 represents the name of the table to be selected from as a string, so for example it could be 'goals'. The error is syntax error at or near "'goals'". I realize that it cannot be a string with single quotes (I believe) and so I am wondering how to convert that variable to be a table name? using "goals" there as well as goals, for example works as expected, though I'm not sure how to do that outside of a function.

CREATE OR REPLACE FUNCTION get_data(user_id INT, table_name anyelement)
RETURNS SETOF ANYELEMENT AS $$
    BEGIN
        RETURN QUERY EXECUTE 
            format('SELECT * FROM %s WHERE user_id = $1', pg_typeof(table_name)) USING user_id;
    END;
$$ LANGUAGE plpgsql;

SELECT * FROM get_data($1, NULL::$2);

$1 is 5 and $2 is 'goals' for example

回答1:

After many hours of trying to figure it out, thanks to Adrian's comment, I found MassiveJS (how I'm connecting to my PostgreSQL server) has inline functions to do queries. In my controller file in my server I was able to create a one line function as such:

const data = await db[tableName].where("user_id=$1", [userId])

Didn't know inline SQL existed in MassiveJS, so that was great to find out!

来源：https://stackoverflow.com/questions/65515168/pl-postgresql-how-to-convert-a-variable-into-a-table-name

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postgresql

plpgsql