628Part IVConnectionsThe following command (Dedicated web hosting) allows us to check
628Part IVConnectionsThe following command allows us to check our result: d cartoonsTable public.cartoons Column | Type | Modifiers———+———————–+———– id | integer | cartoon | character varying(30) | Just so we can say we did something relational, we ll create a second table to hold the namesof some of the characters in these cartoons. CREATE TABLE characters(id int4, character varchar(15)); Postgres offers an astonishing 47 data types, so obviously our example barely even scratchesthe surface. To be clear, some of these types are really other types with increasing data speci- ficity built in. (You may already be familiar with this concept, commonly called an input maskin other database tools.) Now we ll use some SQL to insert a record into the cartoons table. Note that because theserial type is just an integer with an auto-increment flag attached, we do not need to specifyanything for ID: INSERT INTO cartoons (cartoon) values( Scooby Doo ); The absence of an error message suggests our efforts have met with success, but it s a goodidea to check this with a SELECTstatement anyway, first to be sure and second because, after anumber of records have been entered, we may mentally lose track of where the auto-incrementvalue stands. We ll need the number to define a relationship with our characters table. SELECT * from cartoons; id | cartoon—-+———— 1 | Scooby Doo(1 row) Of course, we d be in pretty bad shape if we managed to mess that one up. Let s also put in acharacter or two into the characters table. INSERT INTO characters(id, character) VALUES(1, Shaggy ); INSERT INTO characters(id, character) VALUES(1, Daphne ); So we ve built a database, created a couple of tables, and added a couple of records, just tomake sure things are going well. Before we make a Web application out of this, however, weneed to create a minimally privileged user one who can access the tables in our sampledatabase, write to them, and read from them, but not modify them or investigate any otheraspect of the system. In MySQL, users that did not already exist were implicitly created by the GRANTcommand. While Postgres also uses the GRANTsyntax, we must explicitly create a user first: CREATE USER cartoonfan PASSWORD secretword ; After creating the user, we must give cartoonfansome privileges: GRANT SELECT, INSERT, UPDATE, DELETE on cartoons to cartoonfan; GRANT SELECT, INSERT, UPDATE, DELETE39
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