5.插入数据

The INSERT statement is used to populate a table with rows:

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. The date type is actually quite flexible
in what it accepts, but for this tutorial we will stick to the
unambiguous format shown here.

The 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 because the 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.