# **UNIX_TIMESTAMP()**

## **Function Description**

``UNIX_TIMESTAMP()`` Returns the number of seconds from *1970-01-01 00:00:00* UTC to the current time.

``UNIX_TIMESTAMP(date)`` Returns the value of the parameter to *1970-01-01 00:00:00* UTC to *date* The number of seconds specified.

If the date is out of range passed to ``UNIX_TIMESTAMP()`, it returns 0. If``date`` is ``NULL``, then``NULL`` is returned.

If no parameter is given or the parameter does not contain a fractional second part, the return value is an integer; if the parameter given contains a fractional second part, the return value is ``DECIMAL``.

## **Function Syntax**

```text
> UNIX_TIMESTAMP([date])
```

### **Parameter definition**

| Parameters | Description |
| ---- | ---- |
| date | Optional parameters. The date parameter is a legal date expression. <br> The date parameter can be a ``DATE``, ``DATETIME`` or ``TIMESTAMP`` string, or a numeric in *YYMMDD*, *YYMMDDhhmmss*, *YYYYMMDD*, or *YYYYMMDDhhmmss* format. If the date parameter contains the time part, it selectively contains the fractional part of the second. <br>When the date parameter is ``TIMESTAMP``, ``UNIX_TIMESTAMP()`` directly returns the internal timestamp value without the implicit *string-to-Unix-timestamp* conversion. |

### Conversion between values of non-UTC time zones and Unix timestamp values

If you use `UNIX_TIMESTAMP()` and `FROM_UNIXTIME()` to convert between a non-UTC (Coordinated Universal Time) time zone value and a Unix timestamp value, the conversion is lossy because the mapping is not one-to-one in both directions. For example, `UNIX_TIMESTAMP()` can map two different values in non-UTC time zones to the same Unix timestamp value due to conventions such as daylight saving time (DST). `FROM_UNIXTIME()` maps this value back to only one of the original values. The following example, that is, use different values in the `MET` time zone:

```text
mysql> SET time_zone = 'MET';
Query OK, 0 rows affected (0.01 sec)

mysql> SELECT UNIX_TIMESTAMP('2005-03-27 03:00:00');
+-------------------------------------------+
| unix_timestamp(2005-03-27 03:00:00) |
+-------------------------------------------+
| 1111885200 |
+-------------------------------------------+
1 row in set (0.00 sec)

mysql> SELECT UNIX_TIMESTAMP('2005-03-27 02:00:00');
+-------------------------------------------+
| unix_timestamp(2005-03-27 02:00:00) |
+-------------------------------------------+
| 1111885200 |
+-------------------------------------------+
1 row in set (0.00 sec)

mysql> SELECT FROM_UNIXTIME(1111885200);
+--------------------------------+
| from_unixtime(1111885200) |
+--------------------------------+
| 2005-03-27 03:00:00 |
+--------------------------------+
1 row in set (0.00 sec)
```

## **Example**

```text
mysql> SELECT UNIX_TIMESTAMP("2016-07-11");
+----------------------------------+
| unix_timestamp(2016-07-11) |
+----------------------------------+
| 1468188000 |
+----------------------------------+
1 row in set (0.00 sec)

mysql> SELECT UNIX_TIMESTAMP('2015-11-13 10:20:19');
+-------------------------------------------+
| unix_timestamp(2015-11-13 10:20:19) |
+-------------------------------------------+
| 1447406419 |
+-------------------------------------------+
1 row in set (0.00 sec)

mysql> SELECT UNIX_TIMESTAMP('2015-11-13 10:20:19.012');
+---------------------------------------------------+
| unix_timestamp(2015-11-13 10:20:19.012) |
+---------------------------------------------------+
| 1447406419.012000 |
+---------------------------------------------------+
1 row in set (0.00 sec)
```

## **limit**

Currently, the date format only supports the data formats of `yyyy-mm-dd` and `yyyymmdd`.