Random characters after table name in FROM clause of SELECT query I am rather new to SQL and database administration. I am maintaining/modifying a PHP application that interacts with Postgresql, and have encountered the statement:

SELECT * FROM client_messages c;


I do not understand the meaning of the final 'c' character. In fact, it seems like it is possible to have random characters after the table name in the FROM clause of a SELECT, without affecting the results of the query. Experimenting with the 'psql' utility, I find that these three queries all produce the same result, without any errors:

SELECT * FROM cltk2980dat c LIMIT 5;
SELECT * FROM cltk2980dat LIMIT 5;
SELECT * FROM cltk2980dat kdopwijfdwlhoeufhnekfhyufhf LIMIT 5;


Yet, the author of the program I am maintaining seems to have really wanted that final 'c' character in the SELECT query. I cannot find any explanation for this in manuals of SQL syntax, though I can find explanations of many other ways to modify the FROM clause of a SELECT.

Is there some significance to that final character? Will apparently random characters after the FROM table-name ever have any significance under some circumstances?
As @dezso points out it's a table alias. You can also use as which makes it a bit more comprehendable:

SELECT * FROM client_messages as c


Why use an alias? It makes it easier to refer to the table. Assume the following query:

SELECT * 
FROM client_messages
JOIN client_address
    ON client_messages.client_id = client_address.client_id


Using table aliases:

SELECT * 
FROM client_messages as cm
JOIN client_address as ca
    ON cm.client_id = ca.client_id


so it's a bit shorter which is nice. When using self joins it becomes necessary to use aliases:

SELECT * 
FROM client_messages as cm1
JOIN client_messages as cm2
    ON cm1.x = cm2.y
WHERE cm1.... = ...


Otherwise there is no way to determine which one of the two tables one is referring to.

As a side-note, avoid using SELECT * other than for ad-hoc querying.