'AND' in mysql update request

Question

I executed the following query on mysql by mistake, and mysql executed it without errors:

UPDATE table SET col1='value1' AND col2='value2' WHERE ID='id' 

The request must be

 UPDATE table SET col1='value1', col2='value2' WHERE ID='id' 

So my question is: what did the first request do with an “AND” in fact? For some reason, it seemed like col1 = '0', which seems weird. Is this just a mistake or is this a valid request?

Answer 1

This is what the request really made:

 UPDATE table SET col1=('value1' AND col2='value2') WHERE ID='id'