MySQL/PDO truncates the data

Question

$book is a 7kb string. If this query is executed using PHP PDO exec, the monograph column (LONGTEXT) data gets truncated at 6765 chara

Answer 1

There are two points to be made here. One is that ideally all character encodings must be UTF8 - that's server, client, connection, and table. Two is that PHP's strlen function counts bytes, not characters.

Your table character set may not be set to UTF8. You can do

SHOW CREATE TABLE chemicals;

to check that. You should also add these to your my.cnf:

[mysqld]
character-set-client=utf8
character-set-results=utf8

Read more about MySQL character sets here:

MySQL character sets

Answer 2

It turned out to be that it is encoding issue. The are two solutions. The most obvious is to fix the encoding to match the database/connection settings. In my case, I was getting a iso-8859-1 string and interpreting it as a unicode.

However, it shouldn't be an issue anyway. I went further to discover that PDO::ATTR_EMULATE_PREPARES is set to TRUE by default.

• You will find this topic as a useful summary to understand what does the latter setting mean, PDO MySQL: Use PDO::ATTR_EMULATE_PREPARES or not?.
• This topic will explain why the encoding messed up the query, The way PDO parametrized query works.