Type cast errors in version 9.2 while upgrade

Hi All,

We are doing a postgresql upgrade from version 7.4.30 to 9.2. While testing the queries in newer version, the following error is obtained for some of the queries which were working fine in older version.

"ERROR: operator does not exist: character varying = integer.HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts."
When modified the script to add ' '(quotes) to integer values, the queries are working fine in 9.2 version also. Is this the best fix for this? or is there any other way (adding new type cast??) which will help to overcome this without modifying all the queries? Please advise.

Thanks for your help in advance,Arun