Columns in clients table:
Array
(
    [0] => id
    [1] => client_id
    [2] => name
    [3] => phone
    [4] => phone_no
    [5] => email
    [6] => photo
    [7] => nid
    [8] => id_type
    [9] => dob
    [10] => contact_person
    [11] => contact_number
    [12] => facebook_id
    [13] => occupation
    [14] => occupation_other
    [15] => address
    [16] => flat_no
    [17] => house_no
    [18] => road_no
    [19] => district
    [20] => thana
    [21] => post_code
    [22] => permanent_address
    [23] => permanent_district
    [24] => permanent_post_code
    [25] => permanent_thana
    [26] => zone_id
    [27] => reseller_id
    [28] => mikrotik_router_id
    [29] => olt_device_id
    [30] => onu_serial
    [31] => onu_model
    [32] => onu_ownership
    [33] => onu_rx_power
    [34] => onu_distance
    [35] => onu_status
    [36] => distribution_box
    [37] => connected_by
    [38] => fiber_core_details
    [39] => olt_port
    [40] => package_id
    [41] => ip_address
    [42] => router_ip
    [43] => router_model
    [44] => router_port
    [45] => router_username
    [46] => router_password
    [47] => mac_address
    [48] => pppoe_username
    [49] => pppoe_password
    [50] => connection_type
    [51] => cable_length
    [52] => vlan_box
    [53] => switch_port
    [54] => connection_remarks
    [55] => client_type
    [56] => gender
    [57] => father_name
    [58] => mother_name
    [59] => spouse_name
    [60] => billing_type
    [61] => billing_cycle
    [62] => monthly_bill
    [63] => installation_charge
    [64] => discount
    [65] => pro_rata_bill
    [66] => additional_months
    [67] => payment_method
    [68] => permanent_discount
    [69] => discount_type
    [70] => balance
    [71] => status
    [72] => billing_start_date
    [73] => expire_date
    [74] => scheduled_lock_date
    [75] => lock_comment
    [76] => last_logged_out_at
    [77] => note
    [78] => documents
    [79] => created_at
    [80] => updated_at
    [81] => sub_zone_id
)