Please read this tutorial before to follow this post.
http://www.bsourcecode.com/2013/04/yii-cactivedataprovider-to-excel/ This tutorial will help you to create a excel sheet using custom sql query.In Model Code
public function searchbydocumentdetails(){
$query="SELECT * FROM TABLE_NAME";
return new CSqlDataProvider($query,
array(
'pagination'=>false
)
);
}
In Controller Code
public function customsqltoexcel(){
$document=new Document;
$data=$document->searchbydocumentdetails();
$this->toExcel($data,
array(
'DocuemntName', 'CategoryName', 'DownloadCredits',
'UploadCredits', 'Downloadimits', 'Count', 'Status'
),
'Document Reports',
array( 'creator' => 'Sourcecode'),
'Excel2007'// This is the default value, so you can omit it. You can export to CSV, PDF or HTML too
);
}