Decoupling from the details:

Don't need to worry about what is real The more complex, the more you need views Encapsulation

-- View example setup

CREATE TABLE customer (
  id      SERIAL UNIQUE,
  cname   VARCHAR
);
INSERT INTO customer (cname) VALUES ('Joe Sixpack');
INSERT INTO customer (cname) VALUES ('Jane Sixpack');

CREATE TABLE transaction (
  id           SERIAL UNIQUE,
  customer     INTEGER NOT NULL,
  product      INTEGER NOT NULL,
  price        NUMERIC(6,2) NULL,
  payment_type VARCHAR,
  txndate      TIMESTAMPTZ NOT NULL DEFAULT now()
);
ALTER TABLE transaction ADD CONSTRAINT "txn_cust" FOREIGN KEY (customer) 
REFERENCES customer(id);

INSERT INTO transaction(customer,product,price,payment_type) VALUES (1,26,'5.25','Cash');

INSERT INTO transaction(customer,product,price,payment_type) VALUES (2,4,'150.00','Visa');

oscon=> CREATE VIEW txn AS SELECT * FROM transaction;
CREATE VIEW

oscon=> SELECT * FROM txn;

 id | customer | product | price  | payment_type |            txndate            
----+----------+---------+--------+--------------+-------------------------------
  1 |        1 |      26 |   5.25 | Cash         | 2004-07-22 01:33:47.202985-04
  2 |        2 |       4 | 150.00 | Visa         | 2004-07-22 01:33:50.512945-04


oscon=> SELECT * FROM transaction;

 id | customer | product | price  | payment_type |            txndate            
----+----------+---------+--------+--------------+-------------------------------
  1 |        1 |      26 |   5.25 | Cash         | 2004-07-22 01:33:47.202985-04
  2 |        2 |       4 | 150.00 | Visa         | 2004-07-22 01:33:50.512945-04

Convenience:

oscon=> CREATE USER susan;
CREATE USER

oscon=> CREATE GROUP managers WITH USER mike, susan;
CREATE GROUP

oscon=> REVOKE ALL ON transaction FROM public;
REVOKE

oscon=> REVOKE ALL ON txn FROM public;
REVOKE

oscon=> GRANT SELECT ON txn TO GROUP managers;
GRANT

oscon=> \c oscon susan
You are now connected to database "oscon" as user "susan".

oscon=> SELECT * FROM transaction;
ERROR:  permission denied for relation transaction

oscon=> SELECT * FROM txn;

 id | customer | product | price  | payment_type |            txndate
----+----------+---------+--------+--------------+-------------------------------
  1 |        1 |      26 |   5.25 | Cash         | 2004-07-22 01:33:47.202985-04
  2 |        2 |       4 | 150.00 | Visa         | 2004-07-22 01:33:50.512945-04

Security:

Both at once

1. CREATE VIEW txn2 AS 
2.   SELECT c.cname AS customer, t.price AS Price, t.payment_type AS "Payment Type", 
3.     TO_CHAR(txndate, 'Mon DD, YYYY HH:MM') AS "Payment Date"
4.   FROM transaction t, customer c
5.   WHERE t.customer=c.id;

oscon=> REVOKE ALL ON txn2 FROM public;
REVOKE

oscon=> GRANT SELECT ON txn2 TO GROUP managers;
GRANT

oscon=> SELECT * from txn2;

greg=# SELECT * from txn2;
   customer   | Price  | Payment Type |   Payment Date
--------------+--------+--------------+--------------------
 Joe Sixpack  |   5.25 | Cash         | Jul 22, 2004 10:07
 Jane Sixpack | 150.00 | Visa         | Jul 22, 2004 10:07


oscon=> SELECT * FROM transaction;
 id | customer | product | price  | payment_type |            txndate            
----+----------+---------+--------+--------------+-------------------------------
  1 |        1 |      26 |   5.25 | Cash         | 2004-07-22 01:33:47.202985-04
  2 |        2 |       4 | 150.00 | Visa         | 2004-07-22 01:33:50.512945-04

Better?

Real-life

joymail=> \d spamcount

   View "public.spamcount"
 Column |  Type  | Modifiers
--------+--------+-----------
 ip     | cidr   |
 count  | bigint |
View definition:
 SELECT spamtrack.ip, count(spamtrack.ip) AS count
   FROM spamtrack
  GROUP BY spamtrack.ip
  ORDER BY count(spamtrack.ip) DESC;


SELECT * FROM spamcount;

Security and customization:

oscon=> show search_path;
 search_path
--------------
 $user,public

(mike)
oscon=> SELECT * FROM txn2;
   customer   | Price  | Payment Type |   Payment Date
--------------+--------+--------------+--------------------
 Joe Sixpack  |   5.25 | Cash         | Jul 22, 2004 10:07

(susan)
oscon=> SELECT * FROM txn2;
   customer   |    Email      | Price  | Payment Type |   Payment Date
--------------+---------------+--------+--------------+-------------------
 Joe Sixpack  | joe@gmail.com |   5.25 | Cash         | Jul 22, 2004 10:07

(susan)
managers=> SELECT * FROM txn2;
   customer   | Price  | Payment Type |   Payment Date
--------------+--------+--------------+--------------------
 Joe Sixpack  |   **** | Cash         | Jul 22, 2004 10:07

(susan at 10pm)
managers=> SELECT * FROM txn2;
   customer   | Price  | Payment Type |   Payment Date
--------------+--------+--------------+--------------------
 Joe Sixpack  |  small | Cash         | Jul 22, 2004 10:07

managers=> SELECT * FROM showcustomers();
   customer   | Price  | Payment Type |   Payment Date
 Joe Sixpack  |   5.25 | Cash         | Jul 22, 2004 10:07

Application coping:

Thoughts: