Solve the following sql problem:
Among the subscriber, how many of them finished the 2nd at Folsom and Civic Center BART (7th at Market) as their start and end stations respectively for no more than 490 seconds under minimum visibility of 4 miles.

Schema:
SCHEMA:
- Table: station
  - Column: id
    - Samples: [2, 3, 4, 5, 6]
  - Column: name
    - Samples: [San Jose Diridon Caltrain Station, San Jose Civic Center, Santa Clara at Almaden, Adobe on Almaden, San Pedro Square]
  - Column: lat
    - Samples: [37.329732, 37.330698, 37.333988, 37.331415, 37.336721000000004]
  - Column: long
    - Samples: [-121.90178200000001, -121.888979, -121.894902, -121.8932, -121.894074]
  - Column: dock_count
    - Samples: [27, 15, 11, 19, 15]
  - Column: city
    - Samples: [San Jose, San Jose, San Jose, San Jose, San Jose]
  - Column: installation_date
    - Samples: [8/6/2013, 8/5/2013, 8/6/2013, 8/5/2013, 8/7/2013]
- Table: status
  - Column: station_id
    - Samples: [2, 2, 2, 2, 2]
  - Column: bikes_available
    - Samples: [2, 2, 2, 2, 2]
  - Column: docks_available
    - Samples: [25, 25, 25, 25, 25]
  - Column: time
    - Samples: [2013/08/29 12:06:01, 2013/08/29 12:07:01, 2013/08/29 12:08:01, 2013/08/29 12:09:01, 2013/08/29 12:10:01]
- Table: trip
  - Column: id
    - Samples: [4069, 4073, 4074, 4075, 4076]
  - Column: duration
    - Samples: [174, 1067, 1131, 1117, 1118]
  - Column: start_date
    - Samples: [8/29/2013 9:08, 8/29/2013 9:24, 8/29/2013 9:24, 8/29/2013 9:24, 8/29/2013 9:25]
  - Column: start_station_name
    - Samples: [2nd at South Park, South Van Ness at Market, South Van Ness at Market, South Van Ness at Market, South Van Ness at Market]
  - Column: start_station_id
    - Samples: [64, 66, 66, 66, 66]
  - Column: end_date
    - Samples: [8/29/2013 9:11, 8/29/2013 9:42, 8/29/2013 9:43, 8/29/2013 9:43, 8/29/2013 9:43]
  - Column: end_station_name
    - Samples: [2nd at South Park, San Francisco Caltrain 2 (330 Townsend), San Francisco Caltrain 2 (330 Townsend), San Francisco Caltrain 2 (330 Townsend), San Francisco Caltrain 2 (330 Townsend)]
  - Column: end_station_id
    - Samples: [64, 69, 69, 69, 69]
  - Column: bike_id
    - Samples: [288, 321, 317, 316, 322]
  - Column: subscription_type
    - Samples: [Subscriber, Subscriber, Subscriber, Subscriber, Subscriber]
  - Column: zip_code
    - Samples: [94114, 94703, 94115, 94122, 94597]
- Table: weather
  - Column: date
    - Samples: [8/29/2013, 8/30/2013, 8/31/2013, 9/1/2013, 9/2/2013]
  - Column: max_temperature_f
    - Samples: [74, 78, 71, 74, 75]
  - Column: mean_temperature_f
    - Samples: [68, 69, 64, 66, 69]
  - Column: min_temperature_f
    - Samples: [61, 60, 57, 58, 62]
  - Column: max_dew_point_f
    - Samples: [61, 61, 57, 60, 61]
  - Column: mean_dew_point_f
    - Samples: [58, 58, 56, 56, 60]
  - Column: min_dew_point_f
    - Samples: [56, 56, 54, 53, 58]
  - Column: max_humidity
    - Samples: [93, 90, 93, 87, 93]
  - Column: mean_humidity
    - Samples: [75, 70, 75, 68, 77]
  - Column: min_humidity
    - Samples: [57, 50, 57, 49, 61]
  - Column: max_sea_level_pressure_inches
    - Samples: [30.07, 30.05, 30.0, 29.96, 29.97]
  - Column: mean_sea_level_pressure_inches
    - Samples: [30.02, 30.0, 29.96, 29.93, 29.94]
  - Column: min_sea_level_pressure_inches
    - Samples: [29.97, 29.93, 29.92, 29.91, 29.9]
  - Column: max_visibility_miles
    - Samples: [10, 10, 10, 10, 10]
  - Column: mean_visibility_miles
    - Samples: [10, 10, 10, 10, 10]
  - Column: min_visibility_miles
    - Samples: [10, 7, 10, 10, 6]
  - Column: max_wind_Speed_mph
    - Samples: [23, 29, 26, 25, 23]
  - Column: mean_wind_speed_mph
    - Samples: [11, 13, 15, 13, 12]
  - Column: max_gust_speed_mph
    - Samples: [28, 35, 31, 29, 30]
  - Column: precipitation_inches
    - Samples: [0, 0, 0, 0, 0]
  - Column: cloud_cover
    - Samples: [4, 2, 4, 4, 6]
  - Column: events
    - Samples: [, , , , ]
  - Column: wind_dir_degrees
    - Samples: [286, 291, 284, 284, 277]
  - Column: zip_code
    - Samples: [94107, 94107, 94107, 94107, 94107]

SELECT COUNT(T1.id) FROM trip AS T1 INNER JOIN weather AS T2 ON T2.zip_code = T1.zip_code WHERE T1.subscription_type = 'Subscriber' AND T2.min_visibility_miles = 4 AND T1.duration < 490 AND T1.start_station_name = '2nd at Folsom' AND T1.end_station_name = 'Civic Center BART (7th at Market)'