TO_ISO8601

Description

Converts datetime values to ISO8601 formatted strings, supporting input types DATETIME and DATE. The returned ISO8601 formatted datetime is represented as YYYY-MM-DDTHH:MM:SS, where T is the separator between date and time.

Syntax

TO_ISO8601(`<date_or_date_expr>`)

Parameters

Parameter	Description
<date_or_date_expr>	Input datetime value, supports date/datetime types. For datetime and date formats, please refer to datetime conversion and date conversion

Return Value

Returns VARCHAR type, representing the ISO8601 formatted datetime string.

• If input is DATE (e.g., '2023-10-05'), returns format YYYY-MM-DD (date only);
• If input is DATETIME (e.g., '2023-10-05 15:30:25'), returns format YYYY-MM-DDTHH:MM:SS.xxxxxx (date and time separated by T, xxxxxx are all zeros, fractional seconds in input datetime are rounded to seconds);
• If input is NULL, returns NULL;

Examples

-- Convert DATE type (date only)
SELECT TO_ISO8601(CAST('2023-10-05' AS DATE)) AS date_result;
+--------------+
| date_result  |
+--------------+
| 2023-10-05   |
+--------------+

-- Convert DATETIME type (with hours, minutes, seconds)
SELECT TO_ISO8601(CAST('2020-01-01 12:30:45' AS DATETIME)) AS datetime_result;
+----------------------------+
| datetime_result            |
+----------------------------+
| 2020-01-01T12:30:45.000000 |
+----------------------------+

-- Input with fractional seconds, rounded to seconds
SELECT TO_ISO8601(CAST('2020-01-01 12:30:45.956' AS DATETIME)) AS datetime_result;
+----------------------------+
| datetime_result            |
+----------------------------+
| 2020-01-01T12:30:46.000000 |
+----------------------------+

-- Invalid date (returns NULL)
SELECT TO_ISO8601('2023-02-30') AS invalid_date;
+--------------+
| invalid_date |
+--------------+
| NULL         |
+--------------+

-- Input is NULL (returns NULL)
SELECT TO_ISO8601(NULL) AS null_input;
+------------+
| null_input |
+------------+
| NULL       |
+------------+