> ## Documentation Index > Fetch the complete documentation index at: https://docs.less.tech/llms.txt > Use this file to discover all available pages before exploring further. # Operations Rounds a number to a specified number of decimal places. Can only be used on Decimal columns or expressions that return a decimal. ROUND function Returns the leftmost n characters of a string. Can only be used on String columns or expressions that return a string. LEFT function Returns the rightmost n characters of a string. Can only be used on String columns or expressions that return a string. RIGHT function Returns the substring of a string. Can only be used on String columns or expressions that return a string. A substring is a range of characters within a string. SUBSTRING function Returns the length of a string. Can only be used on String columns or expressions that return a string. LENGTH function Adds or subtracts a number of days, weeks, months, etc to a datetime column. Can only be used on Datetime columns or expressions that return a date. The 'units' must be an integer. The unit can be: 1. 'seconds' 2. 'minutes' 3. 'hours' 4. 'days' 5. 'weeks' 6. 'months' 7. 'years' DATEMATH function Get the difference in duration between two datetime columns or expressions that return a date. Can only be used on Datetime columns or expressions that return a date. The 'units' must be an integer. The unit can be: 1. 'seconds' 2. 'minutes' 3. 'hours' 4. 'days' 5. 'weeks' DATEDIFF function Truncates a datetime column to a specified interval. Can only be used on Datetime columns or expressions that return a date. An example could be truncating to years which for 2025-08-01 would return 2025-01-01. DATETRUNC function Returns the UPPERCASE of a string. Can only be used on String columns or expressions that return a string. UPPER function Returns the LOWERCASE of a string. Can only be used on String columns or expressions that return a string. LOWER function Returns the title case of a string. Can only be used on String columns or expressions that return a string. TITLE function Checks if a string literal exists in a string column or expression that returns a string. Returns a boolean (true or false). This function is case-sensitive. CONTAINS function Checks if a string literal does **not** exist in a string column or expression that returns a string. Returns a boolean (true or false). This function is case-sensitive. DOESNOTCONTAIN function