3.3.4.1. Selecting All Data
The simplest form of SELECT retrieves
everything from a table:
mysql> SELECT * FROM pet;
+----------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+----------+--------+---------+------+------------+------------+
| Fluffy | Harold | cat | f | 1993-02-04 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Fang | Benny | dog | m | 1990-08-27 | NULL |
| Bowser | Diane | dog | m | 1979-08-31 | 1995-07-29 |
| Chirpy | Gwen | bird | f | 1998-09-11 | NULL |
| Whistler | Gwen | bird | NULL | 1997-12-09 | NULL |
| Slim | Benny | snake | m | 1996-04-29 | NULL |
| Puffball | Diane | hamster | f | 1999-03-30 | NULL |
+----------+--------+---------+------+------------+------------+
This form of SELECT is useful if you want
to review your entire table, for example, after you've just
loaded it with your initial dataset. For example, you may
happen to think that the birth date for Bowser doesn't seem
quite right. Consulting your original pedigree papers, you
find that the correct birth year should be 1989, not 1979.
There are least two ways to fix this:
-
Edit the file pet.txt to correct the
error, then empty the table and reload it using
DELETE and LOAD
DATA:
mysql> DELETE FROM pet;
mysql> LOAD DATA LOCAL INFILE 'pet.txt' INTO TABLE pet;
However, if you do this, you must also re-enter the record
for Puffball.
-
Fix only the erroneous record with an
UPDATE statement:
mysql> UPDATE pet SET birth = '1989-08-31' WHERE name = 'Bowser';
The UPDATE changes only the record in
question and does not require you to reload the table.
