Question

I have used this query to alter the table field:

 ALTER TABLE `recordstudent` CHANGE `DATE` `DATE` TEXT NOT NULL UNIQUE;

But I am getting this error:

   ERROR 1170 (42000): BLOB/TEXT column 'DATE' used in key specification without a key length

I am new to this and dont know what to do I googled it but found nothing which I could understand .Please help me to remove this error ,all I want this field as unique.

Answer 1

You can’t have a UNIQUE constraint on a column of unbounded size (TEXT is of “infinite” length).

Try this:

ALTER TABLE `recordstudent` CHANGE `DATE` `DATE` VARCHAR(1024) NOT NULL UNIQUE;

You’ll have to pick a size that’s big enough for your needs (but no bigger)