MYSQL Truncated incorrect DOUBLE value

Question

When the SQL query below is executed:

UPDATE shop_category 
SET name = \'Secolul XVI - XVIII\' 
    AND name_eng = \'16th to 18th centuries\' 
WHERE category         


        

Answer 1

What it basically is

It's incorrect syntax that causes MySQL to think you're trying to do something with a column or parameter that has the incorrect type "DOUBLE".

Learn from my mistake

In my case I updated the varchar column in a table setting NULL where the value 0 stood. My update query was like this:

UPDATE myTable SET myValue = NULL WHERE myValue = 0;

Now, since the actual type of myValue is VARCHAR(255) this gives the warning:

+---------+------+-----------------------------------------------+
| Level   | Code | Message                                       |
+---------+------+-----------------------------------------------+
| Warning | 1292 | Truncated incorrect DOUBLE value: 'value xyz' |
+---------+------+-----------------------------------------------+

And now myTable is practically empty, because myValue is now NULL for EVERY ROW in the table! How did this happen?
^{*internal screaming*}

Over 30k rows now have missing data.
^{*internal screaming intensifies*}

Thank goodness for backups. I was able to recover all the data.
^{*internal screaming intensity lowers*}

The corrected query is as follows:

UPDATE myTable SET myValue = NULL WHERE myValue = '0';
                                                  ^^^
                                                  Quotation here!

I wish this was more than just a warning so it's less dangerous to forget those quotes.

^{*End internal screaming*}