Examples of SQL Comments
These examples illustrate different ways to use the SQL comment indicators.
The following examples use each style of comment indicator, including the
double hyphen ( -- ), braces ( { } ), and C-style
( /* . . . */ ) comment delimiters to include a comment after
an SQL statement. The comment appears on the same line as the statement.
SELECT * FROM customer; -- Selects all columns and rows
SELECT * FROM customer; {Selects all columns and rows}
SELECT * FROM customer; /*Selects all columns and rows*/
The next three examples use the same SQL statement and the same comments
as in the preceding examples, but place the comment on a separate line:
SELECT * FROM customer;
-- Selects all columns and rows
SELECT * FROM customer;
{Selects all columns and rows}
SELECT * FROM customer;
/*Selects all columns and rows*/
In the following examples, the user enters the same SQL statement
as in the preceding example but now a multiple-line comment (or for the double-hyphen
indicator, two comments) follows each statement:
SELECT * FROM customer;
-- Selects all columns and rows
-- from the customer table
SELECT * FROM customer;
{Selects all columns and rows
from the customer table}
SELECT * FROM customer;
/*Selects all columns and rows
from the customer table*/
Comments in any of these styles can also appear within an SQL statement:
SELECT * -- Selects all columns and rows
FROM customer; -- from the customer table
SELECT * {Selects all columns and rows}
FROM customer; {from the customer table}
SELECT * /*Selects all columns and rows*/
FROM customer; /*from the customer table*/
If you use braces or C-style comments that are delimited by paired
opening and closing indicators, the closing comment indicator must be in the
same style as the opening comment indicator.