mysql查询中双引号和单引号之间有什么区别

Question

I found the issue and now my insert query works, but I don't understand why. Here is my current working query:

$add_movie = mysql_query("INSERT INTO ownedmovies VALUES ('', '{$movie_data['Title']}',
    '{$movie_data['Year']}', '{$movie_data['Rated']}', '{$movie_data['Runtime']}',
    '{$movie_data['Genre']}', '{$movie_data['Director']}', '{$movie_data['Writer']}',
    '{$movie_data['Actors']}', \"{$movie_data['Plot']}\", '{$movie_data['imdbRating']}')");

Notice that I used double quotes around the plot field and normal around everything else. When I did the plot field the same way as the others, it would not error but nothing would get inserted into the table... now it works perfectly.

Could anyone enlighten me on why this is?

Thank you

Answer 1

I suspect that your plot string contains a single quote. To avoid the problem you should be escaping your string values using mysql_real_escape_string, or (better) use parameterized queries.

Your "solution" of changing the single quote to a double quote may appear to work in this case, but it will fail if the plot string contains a double quote.