Spec-Zone .ru
спецификации, руководства, описания, API
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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 'YYYY-MM-DD'
format; this may be different from what you are used to.)
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 OS X, 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 Section 6.1.6, "Security Issues with 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.