You are now a sqlite data analyst, and you are given a database schema as follows:

    【Schema】
    【DB_ID】 retail_complains
【Schema】
# Table: reviews
[
(Date:DATE, Primary Key, Examples: [2013-02-04]),
(Stars:INTEGER, Examples: [5, 1, 2]),
(Reviews:TEXT),
(Product:TEXT, Examples: [Eagle National Mortgage]),
(district_id:INTEGER, Examples: [65, 66, 23])
]
# Table: callcenterlogs
[
(Date received:DATE, Examples: [2017-03-27]),
(Complaint ID:TEXT, Primary Key, Examples: [CR0000072, CR0000084, CR0000175]),
(rand client:TEXT, Examples: [C00004587, C00003328, C00001685]),
(phonefinal:TEXT, Examples: [977-806-9726, 322-598-7152, 508-311-5237]),
(vru+line:TEXT, Examples: [AA0103, AA0205, AA0110]),
(call_id:INTEGER, Examples: [34536, 34537, 34538]),
(priority:INTEGER, Examples: [0, 2, 1]),
(type:TEXT, Examples: [NW, PS, NE]),
(outcome:TEXT, Examples: [AGENT, HANG, PHANTOM]),
(server:TEXT, Examples: [MICHAL, TOVA, YIFAT]),
(ser_start:TEXT, Examples: [13:34:11, 10:58:22, 13:00:54]),
(ser_exit:TEXT, Examples: [13:40:23, 11:16:10, 13:13:31]),
(ser_time:TEXT, Examples: [00:06:12, 00:17:48, 00:12:37])
]
# Table: client
[
(client_id:TEXT, Primary Key, Examples: [C00000001, C00000002, C00000003]),
(sex:TEXT, Examples: [Female, Male]),
(day:INTEGER, Examples: [13, 4, 9]),
(month:INTEGER, Examples: [12, 2, 10]),
(year:INTEGER, Examples: [1990, 1965, 1960]),
(age:INTEGER, Examples: [29, 54, 59]),
(social:TEXT, Examples: [926-93-2157, 806-94-5725, 614-70-9100]),
(first:TEXT, Examples: [Emma, Noah, Olivia]),
(middle:TEXT, Examples: [Avaya, Everest, Brooklynne]),
(last:TEXT, Examples: [Smith, Thompson, Johnson]),
(phone:TEXT, Examples: [367-171-6840, 212-423-7734, 212-425-6932]),
(email:TEXT),
(address_1:TEXT, Examples: [387 Wellington Ave., 75 W. Berkshire St., 36 Second St.]),
(address_2:TEXT, Examples: [Unit 1, Unit 6, Unit 80]),
(city:TEXT, Examples: [Albuquerque, New York City, Indianapolis]),
(state:TEXT, Examples: [NM, NY, IN]),
(zipcode:INTEGER, Examples: [47246, 10040, 10162]),
(district_id:INTEGER, Examples: [18, 1, 5])
]
# Table: state
[
(StateCode:TEXT, Primary Key, Examples: [AL, AR, AZ]),
(State:TEXT, Examples: [Alabama, Arkansas, Arizona]),
(Region:TEXT, Examples: [South, West, Northeast])
]
# Table: events
[
(Date received:DATE, Examples: [2014-07-03]),
(Product:TEXT, Examples: [Bank account or service]),
(Sub-product:TEXT, Examples: [Checking account]),
(Issue:TEXT, Examples: [Deposits and withdrawals]),
(Sub-issue:TEXT),
(Consumer complaint narrative:TEXT),
(Tags:TEXT, Examples: [Older American]),
(Consumer consent provided?:TEXT, Examples: [N/A, Consent not provided, Consent provided]),
(Submitted via:TEXT, Examples: [Email, Fax, Postal mail]),
(Date sent to company:TEXT, Examples: [2014-07-09, 2012-04-13, 2012-04-03]),
(Company response to consumer:TEXT, Examples: [Closed with explanation]),
(Timely response?:TEXT, Examples: [Yes, No]),
(Consumer disputed?:TEXT, Examples: [No, Yes]),
(Complaint ID:TEXT, Primary Key, Examples: [CR0000072, CR0000084, CR0000140]),
(Client_ID:TEXT, Primary Key, Examples: [C00003714, C00001366, C00002330])
]
# Table: district
[
(district_id:INTEGER, Primary Key, Examples: [1, 2, 3]),
(city:TEXT, Examples: [New York City, Jacksonville, Columbus]),
(state_abbrev:TEXT, Examples: [NY, FL, OH]),
(division:TEXT, Examples: [Middle Atlantic, South Atlantic, East North Central])
]
【Foreign keys】
reviews.district_id=district.district_id
callcenterlogs.rand client=client.client_id
client.district_id=district.district_id
events.Complaint ID=callcenterlogs.Complaint ID
events.Client_ID=client.client_id
district.state_abbrev=state.StateCode

    【Question】
    In complaints about the credit card product, list the phone number of the oldest client. oldest refers to max(age)

    【Evidence】
    oldest refers to max(age)

    Please read and understand the database schema carefully, and generate an executable SQL based on the user's question and evidence. 

SQL: SELECT T1.phone FROM client AS T1 INNER JOIN events AS T2 ON T1.client_id = T2.Client_ID WHERE T2.Product = 'Credit card' ORDER BY T1.age DESC LIMIT 1