# How the HOUR() function works in Mariadb?

The `HOUR()`

function is a date and time function that returns the hour part of a time or datetime value.

The `HOUR()`

function is a date and time function that returns the hour part of a time or datetime value. It can be used to extract the hour component from a time or datetime value, or to perform calculations based on the hour value. The `HOUR()`

function is compatible with the SQL standard and supports various data types, such as `TIME`

, `DATETIME`

, and `TIMESTAMP`

.

## Syntax

The syntax of the `HOUR()`

function is as follows:

```
HOUR(time)
```

where `time`

is the time or datetime value to be extracted. The function returns an integer value that represents the hour part of the time or datetime value. The value ranges from 0 to 23. If the time or datetime value is `NULL`

, the function returns `NULL`

.

## Examples

### Example 1: Extract the hour part from a time value

The following example uses the `HOUR()`

function to extract the hour part from a time value.

```
SELECT HOUR('09:05:39') AS hour;
```

The function returns an integer value that represents the hour part of the time value. The output is:

```
+------+
| hour |
+------+
| 9 |
+------+
```

The hour part of the time value ‘09:05:39’ is 9.

### Example 2: Extract the hour part from a datetime value

The following example uses the `HOUR()`

function to extract the hour part from a datetime value.

```
SELECT HOUR('2024-02-08 09:05:39') AS hour;
```

The function returns an integer value that represents the hour part of the datetime value. The output is:

```
+------+
| hour |
+------+
| 9 |
+------+
```

The hour part of the datetime value ‘2024-02-08 09:05:39’ is 9.

### Example 3: Extract the hour part from a timestamp value

The following example uses the `HOUR()`

function to extract the hour part from a timestamp value.

```
SELECT HOUR('2024-02-08T09:05:39Z') AS hour;
```

The function returns an integer value that represents the hour part of the timestamp value. The output is:

```
+------+
| hour |
+------+
| 9 |
+------+
```

The hour part of the timestamp value ‘2024-02-08T09:05:39Z’ is 9.

### Example 4: Calculate the difference between two hour values

The following example uses the `HOUR()`

function to calculate the difference between two hour values.

```
SELECT HOUR('12:00:00') - HOUR('09:30:00') AS difference;
```

The function returns an integer value that represents the difference between the hour parts of the two time values. The output is:

```
+------------+
| difference |
+------------+
| 3 |
+------------+
```

The difference between the hour parts of the two time values ‘12:00:00’ and ‘09:30:00’ is 3.

## Related Functions

Some of the functions that are related to the `HOUR()`

function are:

`MINUTE()`

: This function returns the minute part of a time or datetime value. It has the same syntax and behavior as the`HOUR()`

function. For example,`MINUTE('09:05:39')`

returns 5.`SECOND()`

: This function returns the second part of a time or datetime value. It has the same syntax and behavior as the`HOUR()`

function. For example,`SECOND('09:05:39')`

returns 39.`EXTRACT()`

: This function extracts a specific part of a date or time value. It has a different syntax and behavior from the`HOUR()`

function. For example,`EXTRACT(HOUR FROM '09:05:39')`

returns 9.

## Conclusion

The `HOUR()`

function is a useful function to extract the hour part of a time or datetime value. It supports various data types and follows the SQL standard. It can be used to extract the hour component from a time or datetime value, or to perform calculations based on the hour value. It has some related functions that have similar or different functionalities. The `HOUR()`

function is a powerful tool for date and time analysis and manipulation in Mariadb.