MySQL DATE_FORMAT() Data truncation: Incorrect datetime value - mysql

Question

When I run DATE_FORMAT('test', '%W %M %Y') I get null returned.
I'm running an update to my table extras where the column is a nullable varchar, but when I run eg.
update extras
set extras.`value` = DATE_FORMAT('test', '%W %M %Y');
I get the following error:
[22001][1292] Data truncation: Incorrect datetime value: 'test'
extras.value is a varchar column with datetime values some of which are not valid dates. I want to update the column to null when the datetime is invalid ie. just a string as in this case 'test'.

Answer 1

Check does the value is valid date with regular expression.
Example - the most simple pattern which does not check for value validity (and allows, for example, '2022-25-78', in this case the whole UPDATE will fail):
CREATE TABLE test (
id INT AUTO_INCREMENT PRIMARY KEY,
src_value VARCHAR(255),
dst_value VARCHAR(255)
);
INSERT INTO test (src_value) VALUES ('test'), (CURRENT_DATE);
SELECT * FROM test;
id
src_value
dst_value
1
test
null
2
2022-11-22
null
UPDATE test
SET dst_value = DATE_FORMAT(src_value, '%W %M %Y')
WHERE src_value REGEXP '^\\d{4}-\\d{2}-\\d{2}$' ;
SELECT * FROM test;
id
src_value
dst_value
1
test
null
2
2022-11-22
Tuesday November 2022
fiddle

Answer 2

When the STRICT_TRANS_TABLES sql_mode is enabled, any date/time parsing error becomes a fatal error. You have to disable it or use a regex to validate the date string (which is very messy) before using it as a date.
fiddle