Question

I have a column filled with dates, some of which are duplicates, and I want to change all the ones greater than 2012-05-28 to NULL. Here is the statement I’m using:

UPDATE my_data SET date_firstnewtumor=NULL
WHERE date_firstnewtumor>2012-05-28;

However, MySQL Workbench is giving me this error message: “…you tried to update a table without a WHERE that uses a key column.”

I then tried the above code in MySQL Command Line Client and it changed the entire column date_firstnewtumor to NULL.

I’ve looked at examples of code online and I could swear their WHERE statement was similar to mine. What am I doing wrong?

Thank you for your advice!

Answer 1

I think you’ll just want to specify the date literal correctly:

WHERE date_firstnewtumor > '2012-05-28';

Or simply:

WHERE date_firstnewtumor > 20120528;