2.4. Populating a Table With Rows
INSERT statement is used to populate a table with
INSERT INTO weather VALUES ('San Francisco', 46, 50, 0.25, '1994-11-27');
Note that all data types use rather obvious input formats.
Constants that are not simple numeric values usually must be
surrounded by single quotes (
'), as in the example.
date type is actually quite flexible in what it
accepts, but for this tutorial we will stick to the unambiguous
format shown here.
point type requires a coordinate pair as input,
as shown here:
INSERT INTO cities VALUES ('San Francisco', '(-194.0, 53.0)');
The syntax used so far requires you to remember the order of the columns. An alternative syntax allows you to list the columns explicitly:
INSERT INTO weather (city, temp_lo, temp_hi, prcp, date) VALUES ('San Francisco', 43, 57, 0.0, '1994-11-29');
You can list the columns in a different order if you wish or even omit some columns, e.g., if the precipitation is unknown:
INSERT INTO weather (date, city, temp_hi, temp_lo) VALUES ('1994-11-29', 'Hayward', 54, 37);
Many developers consider explicitly listing the columns better style than relying on the order implicitly.
Please enter all the commands shown above so you have some data to work with in the following sections.
You could also have used
COPY to load large
amounts of data from flat-text files. This is usually faster
COPY command is optimized for this
application while allowing less flexibility than
INSERT. An example would be:
COPY weather FROM '/home/user/weather.txt';
where the file name for the source file must be available on the
machine running the backend process, not the client, since the backend process
reads the file directly. You can read more about the
COPY command in COPY.