SQL Server Tutorial SQL Server Advanced SQL Server Database SQL Server References

SQL Server - Comments



The Comments are added in a SQL Server (Transact-SQL) statement with the purpose of making the statement easier to understand. It makes the statement more readable and hence easier to update it later. Comments are ignored when the statement is executed. In SQL Server (Transact-SQL), there are two ways of putting a comment.

  • Single line comment
  • Multi-line comment

Consider a database table called Employee with the following records:

EmpIDNameCityAgeSalary
1JohnLondon253000
2MarryNew York242750
3JoParis272800
4KimAmsterdam303100
5RameshNew Delhi283000
6HuangBeijing282800

Single line Comment

It starts with -- and ends with the end of that line. Anything after -- to the end of the line is a single line comment and will be ignored when the statement is executed.

Example:

In the example below, two line comments are used. Comments are ignored when query is executed.

-- first line comment
SELECT Name, Salary FROM Employee; -- second line comment

This will produce the result as shown below:

NameSalary
John3000
Marry2750
Jo2800
Kim3100
Ramesh3000
Huang2800

Multi-line Comment

It starts with /* and ends with */. Anything between /* and */ is a block comment and will be ignored when the query is executed.

Example:

In the below query, multi-line comments are used. When this query is executed these block of comments will be ignored.

/* comment line 1
comment line 2 */
SELECT EmpID, Name, City  /* more comments */  FROM Employee; 

This result of the above query will be:

EmpIDNameCity
1JohnLondon
2MarryNew York
3JoParis
4KimAmsterdam
5RameshNew Delhi
6HuangBeijing

5