How to deal with an apostrophe while writing into a MySQL database

Question

I am getting this error:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 's','portal','','offering','MSNBC','News','','sports','','MSN','Money','','games'' at line 3

The only problem is that this error shows up when inserting data that contains an apostrophe. I tried changing the data type from VARCHAR to TEXT, but the result is still the same.

I tried to put in addslashes()

How do I fix this?

$query=" INSERT INTO alltags
 (id,tag1,tag2,tag3,tag4,tag5,tag6,tag7,tag8,tag9,tag10,tag11,tag12,tag13,tag14,tag15,tag16,tag17,tag18,tag19,tag20,tag21,tag22,tag23,tag24,tag25,tag26,tag27,tag28,tag29,tag30)
VALUES      
 ('',mysql_real_escape_string($uniqkey[0]),mysql_real_escape_string($uniqkey[1]),mysql_real_escape_string($uniqkey[2]),mysql_real_escape_string($uniqkey[3]),mysql_real_escape_string($uniqkey[4]),mysql_real_escape_string($uniqkey[5]),mysql_real_escape_string($uniqkey[6]),mysql_real_escape_string($uniqkey[7]),mysql_real_escape_string($uniqkey[8]),mysql_real_escape_string($uniqkey[9]),mysql_real_escape_string($uniqkey[10]),mysql_real_escape_string($uniqkey[11]),mysql_real_escape_string($uniqkey[12]),mysql_real_escape_string($uniqkey[13]),mysql_real_escape_string($uniqkey[14]),mysql_real_escape_string($uniqkey[15]),mysql_real_escape_string($uniqkey[16]),mysql_real_escape_string($uniqkey[17]),mysql_real_escape_string($uniqkey[18]),mysql_real_escape_string($uniqkey[19]),mysql_real_escape_string($uniqkey[20]),mysql_real_escape_string($uniqkey[21]),mysql_real_escape_string($uniqkey[22]),mysql_real_escape_string($uniqkey[23]),mysql_real_escape_string($uniqkey[24]),mysql_real_escape_string($uniqkey[25]),mysql_real_escape_string($uniqkey[26]),mysql_real_escape_string($uniqkey[27]),mysql_real_escape_string($uniqkey[28]),mysql_real_escape_string($uniqkey[29])) "; 
mysql_query($query) or die(mysql_error());

I changed it to mysql_real_escape_string. Is this syntax correct? I am getting errors.

Answer 1

The process of encoding data which contains characters MySQL might interpret is called "escaping". You must escape your strings with mysql_real_escape_string, which is a PHP function, not a MySQL function, meaning you have to run it in PHP before you pass your query to the database. You must escape any data that comes into your program from an external source. Any data that isn't escaped is a potential SQL injection.

You have to escape your data before you build your query. Also, you can build your query programmatically using PHP's looping constructs and range:

// Build tag fields
$tags = 'tag' . implode(', tag', range(1,30));

// Escape each value in the uniqkey array
$values = array_map('mysql_real_escape_string', $uniqkey);

// Implode values with quotes and commas
$values = "'" . implode("', '", $values) . "'";

$query = "INSERT INTO alltags (id, $tags) VALUES ('', $values)";

mysql_query($query) or die(mysql_error());