The syntax used to invoke SQL*Plus looks like this:

sqlplus [[-S[ILENT]] [-R[ESTRICT] level]
   [-M[ARKUP] markup_options]
   [username[/password][@connect]|/|/NOLOG]
   [@scriptfile [arg1 arg2 arg3...]]] | - | -?

The -RESTRICT and -MARKUP parameters are new in release 8.1.6. The descriptions of the parameters follow:

Commands such as DESCRIBE, COLUMN, TTITLE, SET, and all the others listed in the Section 1.7 section are commands to SQL*Plus itself. These must be entered on one line and are executed immediately after you enter them. For example:

SET ECHO ON
DESCRIBE employee

SQL*Plus commands may optionally be terminated by a semicolon. For example:

PROMPT This semicolon won't print.;
CONNECT system/manager;

You can change this behavior of SQL*Plus towards semi-colons by changing the SQLTERMINATOR setting.

Long SQL*Plus commands may be continued onto multiple physical lines. The SQL*Plus continuation character is a hyphen (-). Use it at the end of a physical line to continue a long SQL*Plus command to the next line. The following three lines, for example, are treated as one by SQL*Plus:

COLUMN employee_id -
FORMAT 099999 -
HEADING 'Emp ID'

The space in front of the continuation character is optional. Quote strings may also be continued. For example:

SELECT 'Hello-
World!' FROM dual;

When you are continuing a quoted string, any spaces before the continuation character will be included in the string. The line break also counts as one space.

SQL statements may span multiple lines and must always be terminated. This may be done using either a semi-colon ( ; ) or a forward slash ( / ). For example:

SELECT user
FROM dual;
SELECT user
FROM dual
/

In both of these cases, the SQL statement will be entered into a buffer known as the SQL buffer and then will be executed. You may also terminate a SQL statement using either a blank line or a period, in which case the statement is stored in the buffer but not executed. For example:

SQL> SELECT user
  2  FROM dual
  3  
SQL> SELECT user
  2  FROM dual
  3  .

Use the SET SQLTERMINATOR command to change the terminator from a semicolon to some other character. Use SET SQLBLANKLINES ON to allow blank lines within a SQL statement. To execute the statement currently in the buffer, enter a forward slash on a line by itself.

PL/SQL blocks may span multiple lines and may contain blank lines. They must be terminated by either a forward slash or a period (.) on a line by itself. For example:

BEGIN
   DBMS_OUTPUT.PUT_LINE('Hello World!'),
END;
/

BEGIN
   DBMS_OUTPUT.PUT_LINE('Hello World!'),
END;
.

When a forward slash is used, the block is sent to the server and executed immediately. When a period is used, the block is only stored in the SQL buffer. Use the SET BLOCKTERMINATOR command to change the block terminator from a period to some other character.

If a SELECT statement includes columns that are expressions, Oracle will generate a column name based on the expression. Take a look at the following SQL statement:

SELECT SUM(hours_logged)
FROM project_hours
WHERE project_id = 1001;

The name of the column returned by this query will be SUM(HOURS_LOGGED). That means that any COLUMN commands used to format the output will need to look like this:

COLUMN SUM(HOURS_LOGGED) -
HEADING 'Total Hours'

As your expressions become more complicated, the Oracle-generated names become difficult to deal with. It’s better to use a column alias to supply a more user-friendly name for the computed column. For example:

SELECT SUM(hours_logged) total_hours
FROM project_hours
WHERE project_id = 1001;

Now the column name is obvious. It’s total_hours, and it won’t change even if the expression changes.