MySQL HOUR() Function

 The HOUR() function in MySQL is used to extract the hour portion from a given time or datetime expression. It returns an integer value representing the hour (in 24-hour format, ranging from 0 to 23).

Syntax

HOUR(time)

Parameters

• time: A valid time or datetime expression from which the hour will be extracted.

Returns

• An integer between 0 and 23.
• If the input is NULL or an invalid time, the function returns NULL.

Examples

1. Extract hour from a time value

   SELECT HOUR('14:35:59') AS Hour;
   

   Result: 14

2. Extract hour from a datetime value

   SELECT HOUR('2023-12-23 18:45:00') AS Hour;
   

   Result: 18

3. Using with a column in a table Suppose you have a table events with a column event_time (datatype DATETIME):

   SELECT event_time, HOUR(event_time) AS EventHour
   FROM events;
   

4. Using with CURRENT_TIME or NOW()

   SELECT HOUR(NOW()) AS CurrentHour;
   

   Result: (Returns the current hour of the server time.)

5. Invalid or NULL input

   SELECT HOUR('Invalid Time') AS Hour, HOUR(NULL) AS HourWithNull;
   

   Result: NULL, NULL

Use Case

The HOUR() function is commonly used when you need to group or filter records by the hour part of a time or datetime column, such as analyzing hourly trends in data.

For example:

SELECT HOUR(event_time) AS Hour, COUNT(*) AS EventCount
FROM events
GROUP BY HOUR(event_time);