SQL Comments

Comments are used to explain sections of SQL statements, or to prevent execution of SQL statements.

Note: Note: Comments are not supported in Microsoft Access databases!

Single Line Comments

Single line comments start with -- .

Any text between -- and the end of the line will be ignored (will not be executed).

The following example uses a single-line comment as an explanation:

Example

--Select all:   
 SELECT  * 
 FROM  supplier  ;

You can click on above box to edit the code and run again.

The following example uses a single-line comment to ignore the end of a line:

Example

 SELECT  * 
 FROM  supplier --WHERE City='Hydrabad' ;

You can click on above box to edit the code and run again.

Multi-line Comments

Multi-line comments start with /* and end with /* .

Any text between /* and */ will be ignored.

The following example uses a multi-line comment as an explanation:

Example

 /*Select all the columns
of all the records
 in the employee table:*/
 
  SELECT  * 
  FROM  employee;

You can click on above box to edit the code and run again.

The following example uses a multi-line comment to ignore many statements:

Example

 /*SELECT * FROM Customers;

 SELECT * FROM Products;

 SELECT * FROM Categories;*/
 
 SELECT  * 
 FROM  employee;

You can click on above box to edit the code and run again.

To ignore just a part of a statement, also use the /* */ comment.

The following example uses a comment to ignore part of a line:

Example

 SELECT  Employee_name,/* City,*/ Country 
 FROM  employee;

You can click on above box to edit the code and run again.

Output