Comments
Notes inside a statement. The engine skips them.
Syntax
-- <text to the end of the line>
/* <text, over any number of lines> */
Usage notes
- A line comment starts at
--and runs to the end of the line. - A block comment runs from
/*to the matching*/. Block comments nest, as in PostgreSQL:/* a /* b */ c */is one comment. - An unterminated block comment is an error.
--and/*inside a quoted string are part of the string, not a comment.- A comment can go anywhere whitespace can, including inside the body of a view, a materialized view or a tool.
- To describe a view, a column or a tool for the people and agents who read it, use COMMENT ON: a comment in the text is not shown to them.
Examples
-- Open orders over a threshold
SELECT o.key, o.amount -- amount is in dollars
FROM Order o
WHERE o.status = 'open'
/* held orders are left out on purpose:
they are reviewed elsewhere */
AND o.amount > 1000
A dash pair inside a string is text:
SELECT t.name FROM tables.drive.file t WHERE t.name LIKE '%--draft%'
Not supported
| Refused | Write instead |
|---|---|
| An unterminated block comment | Close it with */ |
# line comments | -- |
-- Refused by the engine
SELECT o.key FROM Order o /* never closed
-- Refused by the engine
SELECT o.key FROM Order o # a note