Can you tell me what is the different using (')single quotes
inside (")quotes
and (")quotes
inside (')single quotes
? and at concat, what is the meaning of this '".$bla."'
I still can not distinguish them.
In SQL, anything with single quotes is considered a text based data type.
SQL uses double quotes for escaping keywords and non-ASCII characters.
This:
'". $bla ."'
..is PHP syntax. $bla is a PHP variable, the period is a string concatenation character (which is why there's one on both sides). So in this example, the content of the $bla variable is being concatenated into a string, where it will be surrounded by single quotes.