UPDATE cell to be empty MYSQL PHP

问题

Looked around on Google and Stack Overflow, maybe I'm just blind though. Is there a way to UPDATE a table cell with an " " (empty) value. Let's say like:

mysql_query("UPDATE table SET cellname = ' ' WHERE id = '$idneeded'");

Any help much appreciated.

回答1:

you should know that empty string '' is not same as space string ' ' and not same as NULL value.

to update the cell value to empty string :

mysql_query("UPDATE table SET cellname = '' WHERE id = '$idneeded'");

回答2:

UPDATE table SET cellname = ' ' WHERE id = '$idneeded'
                            ^^^---not empty. spaces are not "empty".

Try

cellname=''

or

cellname=NULL

instead.

来源：https://stackoverflow.com/questions/13014836/update-cell-to-be-empty-mysql-php