need script db size reaches to 90%?

You need to investigate Alerts and Operators.

For example you could alert on a given data size, if your databases are fixed size and not set to auto-grow.

If there is no alert suitable for your scenario, then maybe have a scheduled job that runs periodically and fires an email to your defined Operators, using sp_send_dbmail when the condition is reached.

Not sure you relate the DB Size to Data Files Size With/Without including Log files? Anyways, how about the following script to know the Data/Log files sizes and the space remining. You can use a CURSOR / LOOP to get all the databases information

SELECT  *
FROM    ( SELECT    DB_NAME() DBName
          ,         df.name AS [FileName]
          ,         physical_name AS PhysicalName
          , [type_desc] FileTypeDescription
          ,         size / 128 AS TotalSizeinMB
          ,         size / 128.0
                    - CAST(FILEPROPERTY(df.name, 'SpaceUsed') AS FLOAT)
                    / 128.0 AS AvailableSpaceInMB
          ,         CAST(FILEPROPERTY(df.name, 'SpaceUsed') AS FLOAT) / 128.0 AS ActualSpaceUsedInMB
          ,         ( ( CAST(FILEPROPERTY(df.name, 'SpaceUsed') AS FLOAT)
                        / 128.0 ) / ( size / 128.0 ) ) * 100.0 AS PercentageSpaceUsed
          FROM      sys.database_files df
          WHERE     [type] IN ( 0, 1 )
        ) A
WHERE   PercentageSpaceUsed >= '90' 

Moreover, you can filter out some output using type column as used in the WHERE clause to return information about the DATA and Log files. Hope it helps.

Kev probably has the best answer with the alerts and operators, but I would add that specialized Monitoring tools like SQL Monitor will handle this very simply s well as many other monitoring tasks.