用另一个值替换第一个实例NULL或'' - MySQL [关闭]

Question

I'm trying to replace the first instance of a NULl or ' ' value in a column with another value. But only the first instance and nothing else.

So far I've put this together:

UPDATE table_name SET column = CONCAT(REPLACE(LEFT(column , INSTR(column , '')), '', 'new_value'), SUBSTRING(column , INSTR(column , '') +1))

I could replace all the values but I don't want that:

UPDATE table_name SET column = REPLACE (column , 'old_value', 'new_value')

Answer 1

Just try using limit 1

  UPDATE table_name SET column='new_value' WHERE column='' limit 1