SQL | Comments

As is any programming languages comments matter a lot in SQL also. In this set we will learn about writing comments in any SQL snippet.

Comments can be written in the following three formats:

  1. Single line comments.
  2. Multi line comments
  3. In line comments

  • Single line comments: Comments starting and ending in a single line are considered as single line comments.
    Line starting with ‘–‘ is a comment and will not be executed.
    Syntax:

    --single line comment
    --another comment
    SELECT * FROM Customers; 
    
  • Multi line comments: Comments starting in one line and ending in different line are considered as multi line comments. Line starting with ‘/*’ is considered as starting point of comment and are terminated when ‘*/’ is encountered.
    Syntax:

    /* multi line comment
    another comment */
    SELECT * FROM Customers; 
    

  • In line comments: In line comments are an extension of multi line comments, comments can be stated in between the statements and are enclosed in between ‘/*’ and ‘*/’.
    Syntax:

    SELECT * FROM /* Customers; */ 
    

    More examples:

    Multi line comment ->
    /* SELECT * FROM Students;
    SELECT * FROM STUDENT_DETAILS;
    SELECT * FROM Orders; */
    SELECT * FROM Articles; 
    
    In line comment ->
    SELECT * FROM Students;
    SELECT * FROM /* STUDENT_DETAILS;
    SELECT * FROM Orders;
    SELECT * FROM */ Articles; 
    

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