SQL Comments
SQL Comments
SQL comments are used to add notes or explanations to SQL code without affecting the actual execution of the code. There are two types of comments in SQL: single-line comments and multi-line comments.
- Single-line comments: Single-line comments start with two hyphens (–). Any text after the hyphens on the same line is treated as a comment and ignored by the SQL engine. Here is an example:
SELECT column1, column2 -- This is a comment
FROM table_name;
In this example, the text “This is a comment” is a single-line comment that explains what the query is doing.
- Multi-line comments: Multi-line comments start with /* and end with */. Any text between these symbols is treated as a comment and ignored by the SQL engine. Here is an example:
/* This is a multi-line comment
that spans multiple lines */
SELECT column1, column2
FROM table_name;
In this example, the text “This is a multi-line comment that spans multiple lines” is a multi-line comment that explains what the query is doing.
Comments are useful for documenting SQL code and making it easier to understand and maintain. They can also be used for testing and debugging purposes, as well as for communicating with other developers who may need to work on the same code. It is good practice to include comments in your SQL code to improve its readability and maintainability.