Use `–` for a single-line comment
Use `/* comment */` for a multi-line comment
Place `–` before the text to comment out the rest of a line
Place `/*` before and `*/` after the text to comment out a block
Use `#` for single-line comments in MySQL
Use `REM` for comments in some SQL tools and dialects
Use comments to temporarily disable SQL code
Use comments to add notes inside SQL queries