- You can combine literals, operators, and built-in functions in countless ways to produce expressions.
- A constant value such as a string, a number, or a NULL value.
- Perform math in your query.
- An important concept in mathematics is operator precedence, which means the order of operations. Precedence means that higher-level mathematical operations will be performed first so that multiplication and division are done before addition and subtraction. You can add parentheses around calculations to impact the precedence.
- String, numeric, and date.
- Converts text to lowercase.
- Converts a value into the specified data type.
- The query may no longer use the indexes on the table.
- STDDEV(column)
- Virtual and stored.
