1. Aggregate Functions

• COUNT(): Counts the number of rows.
• SUM(): Calculates the sum of values in a column.
• AVG(): Calculates the average of values in a column.
• MIN(): Retrieves the minimum value in a column.
• MAX(): Retrieves the maximum value in a column.

2. String Functions

• CONCAT(): Concatenates two or more strings.
• SUBSTRING(): Extracts a substring from a string.
• UPPER(): Converts a string to uppercase.
• LOWER(): Converts a string to lowercase.
• LENGTH() or LEN(): Calculates the length of a string.
• TRIM(): Removes leading and trailing spaces.
• LEFT(), RIGHT(): Extracts characters from the left or right of a string.

3. Date and Time Functions

• CURRENT_DATE: Returns the current date.
• CURRENT_TIME: Returns the current time.
• CURRENT_TIMESTAMP: Returns the current timestamp (date and time).
• DATE(): Extracts the date part from a timestamp.