Problem while searching for the string(Arabic) in the column in oracle database?

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C#

Oracle

C#4.0

Hi EveryOne..
I have a problem while updating the database table using update query in the asp.net. the problem is here the search string is in arabic
My update command woulb be something like this
for Example

update tableName set column1=xyuz where id="arabicData" ;

if ever the search string is alphabets or Numeric its working fine and also i can insert the arabic data using insert statements but not able search using the arabic string ..
the Database is Oracle 10g , visiualstudio 2008 Asp.net C#,Ado.net.
please provide me a solution...