sql 转换占用空间的单位

(
            CASE
                    
                    WHEN IFNULL( ppam_res.table_size, 0 ) > 1024.0 * 1024.0 * 1024.0 * 1024.0 THEN
                    concat( ROUND( ppam_res.table_size / ( 1024.0 * 1024.0 * 1024.0 * 1024.0 ), 2 ), 'TB' ) 
                    WHEN IFNULL( ppam_res.table_size, 0 ) > 1024 * 1024 * 1024 THEN
                    concat( ROUND( ppam_res.table_size / ( 1024.0 * 1024 * 1024 ), 2 ), 'GB' ) 
                    WHEN IFNULL( ppam_res.table_size, 0 ) > 1024.0 * 1024.0 THEN
                    concat( ROUND( ppam_res.table_size / ( 1024.0 * 1024.0 ), 2 ), 'MB' ) 
                    WHEN IFNULL( ppam_res.table_size, 0 ) > 1024.0 THEN
                    concat( ROUND( ppam_res.table_size / ( 1024.0 ), 2 ), 'KB' ) 
                    WHEN IFNULL( ppam_res.table_size, 0 ) <  1024.0 THEN
                    concat ( ppam_res.table_size, 'B' ) ELSE '0B' 
                END 
                ) capacity