insert a special character - Mailing list pgsql-php

hello,
       I have a string with ' this symbol in the middle of  the text
     example:-
             " that book belong to rahul's sister"

    this string is to be stored in the variable "$strexp"
    when I am inserting this variable in database table
    following error apperes


   " parse error at or near "s" "

    How can I read the string and store in a variable and insert the same
into the database table ?

thanks in advance ,
with regards,
Arun