Prepend table name to each column in a result set in SQL? (Postgres specifically)

Question

How can I get the label of each column in a result set to prepend the name if its table?

I want this to happen for queries on single tables as well as joins.

Answer 1

To get the VIEW (Daryl's idea) in a single statement use a function or a DO command with EXECUTE:

DO
$do$
BEGIN

EXECUTE (
   SELECT format(
      'CREATE TEMP VIEW people AS SELECT %s FROM %I'
     , string_agg(format('%I AS %I', attname, attrelid::regclass || '.' || attname), ', ')
     , attrelid::regclass)
   FROM   pg_attribute
   WHERE  attrelid = 'person'::regclass  -- supply source table name once
   AND    attnum > 0
   AND    NOT attisdropped
   GROUP  BY attrelid
   );

END
$do$;

This immediately executes a command of the form:

CREATE OR REPLACE VIEW people AS
SELECT person_id AS "person.person_id"
     , first_name AS "person.first_name"
     , last_name AS "person.last_name"
FROM   person;

Would be less hassle to concatenate legal column names with '_' instead of '.'. But you need to be prepared for non-standard names that require double-quoting (and defend against possible SQL injection) anyway.

You can optionally provide a schema-qualified table name (myschema.person). The schema-name is prefixed in column names automatically if it is outside the current search_path.

For repeated use, you wrap this into a plpgsql function and make the table name a text parameter. All text-to-code conversion is sanitized here to prevent SQL injection. Example with more information here:

• Table name as a PostgreSQL function parameter

And you might use the new to_regclass() in Postgres 9.4+:

• How to check if a table exists in a given schema