1.4. Populating a Table With Rows

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

INSERT INTO emp VALUES (7369,'SMITH','CLERK',7902,'17-DEC-80',800,NULL,20);

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.

A sample insert into the dept table would look like:

INSERT INTO dept VALUES (10,'ACCOUNTING','NEW YORK');

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 emp(empno,ename,job,mgr,hiredate,sal,comm,deptno)
VALUES (7499,'ALLEN','SALESMAN',7698,'20-FEB-81',1600,300,30)

You can list the columns in a different order if you wish or even omit some columns, e.g., if the commission is unknown:

INSERT INTO emp(empno,ename,job,mgr,hiredate,sal,deptno)
VALUES (7369,'SMITH','CLERK',7902,'17-DEC-80',800,20);

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 emp FROM '/home/user/emp.txt';

where the file name for the source file must be available to the backend server machine, not the client, since the backend server reads the file directly. You can read more about the COPY command in COPY.