After creating your table, you need to populate it. The
LOAD DATA
and
INSERT
statements are useful for
this.
Suppose that your pet records can be described as shown here.
(Observe that MySQL expects dates in
'
format; this may differ from what you are used to.)
YYYY-MM-DD
'
name | owner | species | sex | birth | death |
---|---|---|---|---|---|
Fluffy | Harold | cat | f | 1993-02-04 | |
Claws | Gwen | cat | m | 1994-03-17 | |
Buffy | Harold | dog | f | 1989-05-13 | |
Fang | Benny | dog | m | 1990-08-27 | |
Bowser | Diane | dog | m | 1979-08-31 | 1995-07-29 |
Chirpy | Gwen | bird | f | 1998-09-11 | |
Whistler | Gwen | bird | 1997-12-09 | ||
Slim | Benny | snake | m | 1996-04-29 |
Because you are beginning with an empty table, an easy way to populate it is to create a text file containing a row for each of your animals, then load the contents of the file into the table with a single statement.
You could create a text file pet.txt
containing one record per line, with values separated by tabs,
and given in the order in which the columns were listed in the
CREATE TABLE
statement. For
missing values (such as unknown sexes or death dates for animals
that are still living), you can use NULL
values. To represent these in your text file, use
\N
(backslash, capital-N). For example, the
record for Whistler the bird would look like this (where the
whitespace between values is a single tab character):
Whistler Gwen bird \N 1997-12-09 \N
To load the text file pet.txt
into the
pet
table, use this statement:
mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet;
If you created the file on Windows with an editor that uses
\r\n
as a line terminator, you should use
this statement instead:
mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet
LINES TERMINATED BY '\r\n';
(On an Apple machine running macOS, you would likely want to use
LINES TERMINATED BY '\r'
.)
You can specify the column value separator and end of line
marker explicitly in the LOAD
DATA
statement if you wish, but the defaults are tab
and linefeed. These are sufficient for the statement to read the
file pet.txt
properly.
If the statement fails, it is likely that your MySQL installation does not have local file capability enabled by default. See Security Considerations for LOAD DATA LOCAL, for information on how to change this.
When you want to add new records one at a time, the
INSERT
statement is useful. In
its simplest form, you supply values for each column, in the
order in which the columns were listed in the
CREATE TABLE
statement. Suppose
that Diane gets a new hamster named “Puffball.” You
could add a new record using an
INSERT
statement like this:
mysql> INSERT INTO pet
VALUES ('Puffball','Diane','hamster','f','1999-03-30',NULL);
String and date values are specified as quoted strings here.
Also, with INSERT
, you can insert
NULL
directly to represent a missing value.
You do not use \N
like you do with
LOAD DATA
.
From this example, you should be able to see that there would be
a lot more typing involved to load your records initially using
several INSERT
statements rather
than a single LOAD DATA
statement.