Slash Star (Block Comment) (Transact-SQL)
Indicates user-provided text. The text between the /* and */ is not evaluated by the server.
/* text_of_comment */
Is the text of the comment. This is one or more character strings.
Comments can be inserted on a separate line or within a Transact-SQL statement. Multiple-line comments must be indicated by /* and */. A stylistic convention often used for multiple-line comments is to begin the first line with /*, subsequent lines with **, and end with */.
There is no maximum length for comments.
Nested comments are supported. If the /* character pattern occurs anywhere within an existing comment, it is treated as the start of a nested comment and, therefore, requires a closing */ comment mark. If the closing comment mark does not exist, an error is generated.
For example, the following code generates an error.
DECLARE @comment AS varchar(20); GO /* SELECT @comment = '/*'; */ SELECT @@VERSION; GO
To work around this error, make the following change.
DECLARE @comment AS varchar(20); GO /* SELECT @comment = '/*'; */ */ SELECT @@VERSION; GO
The following example uses comments to explain what the section of the code is supposed to do.
USE AdventureWorks2012; GO /* This section of the code joins the Person table with the Address table, by using the Employee and BusinessEntityAddress tables in the middle to get a list of all the employees in the AdventureWorks2012 database and their contact information. */ SELECT p.FirstName, p.LastName, a.AddressLine1, a.AddressLine2, a.City, a.PostalCode FROM Person.Person AS p JOIN HumanResources.Employee AS e ON p.BusinessEntityID = e.BusinessEntityID JOIN Person.BusinessEntityAddress AS ea ON e.BusinessEntityID = ea.BusinessEntityID JOIN Person.Address AS a ON ea.AddressID = a.AddressID; GO