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

    【Schema】
    【DB_ID】 superstore
【Schema】
# Table: south_superstore
[
(Row ID:INTEGER, Primary Key, Examples: [10343, 10344, 10345]),
(Order ID:TEXT, Examples: [CA-2011-106054, CA-2011-167199, CA-2011-149020]),
(Order Date:DATE, Examples: [2013-01-06]),
(Ship Date:DATE, Examples: [2013-01-07]),
(Ship Mode:TEXT, Examples: [First Class, Standard Class, Second Class]),
(Customer ID:TEXT, Examples: [JO-15145, ME-17320, AJ-10780]),
(Region:TEXT, Examples: [South]),
(Product ID:TEXT, Examples: [OFF-AR-10002399, FUR-CH-10004063, OFF-BI-10004632]),
(Sales:REAL, Examples: [12.78, 2573.82, 609.98]),
(Quantity:INTEGER, Examples: [3, 9, 2]),
(Discount:REAL, Examples: [0.0, 0.7, 0.2]),
(Profit:REAL, Examples: [5.2398, 746.4078, 274.491])
]
# Table: people
[
(Customer ID:TEXT, Primary Key, Examples: [AA-10315, AA-10375, AA-10480]),
(Customer Name:TEXT, Examples: [Alex Avila, Allen Armold, Andrew Allen]),
(Segment:TEXT, Examples: [Consumer, Home Office, Corporate]),
(Country:TEXT, Examples: [United States]),
(City:TEXT, Examples: [Round Rock, Omaha, Springfield]),
(State:TEXT, Examples: [Texas, Nebraska, Missouri]),
(Postal Code:INTEGER, Examples: [78664, 68104, 65807]),
(Region:TEXT, Primary Key, Examples: [Central, East, West])
]
# Table: west_superstore
[
(Row ID:INTEGER, Primary Key, Examples: [13583, 13584, 13585]),
(Order ID:TEXT, Examples: [CA-2011-130813, CA-2011-157147, CA-2011-123477]),
(Order Date:DATE, Examples: [2013-01-06]),
(Ship Date:DATE, Examples: [2013-01-08]),
(Ship Mode:TEXT, Examples: [Second Class, Standard Class, First Class]),
(Customer ID:TEXT, Examples: [LS-17230, BD-11605, DW-13195]),
(Region:TEXT, Examples: [West]),
(Product ID:TEXT, Examples: [OFF-PA-10002005, OFF-ST-10000078, FUR-BO-10003034]),
(Sales:REAL, Examples: [19.44, 1325.85, 333.999]),
(Quantity:INTEGER, Examples: [3, 5, 4]),
(Discount:REAL, Examples: [0.0, 0.15, 0.2]),
(Profit:REAL, Examples: [9.3312, 238.653, 3.9294])
]
# Table: east_superstore
[
(Row ID:INTEGER, Primary Key, Examples: [4647, 4648, 4649]),
(Order ID:TEXT, Examples: [CA-2011-141817, CA-2011-130092, CA-2011-118192]),
(Order Date:DATE, Examples: [2013-01-05]),
(Ship Date:DATE, Examples: [2013-01-12]),
(Ship Mode:TEXT, Examples: [Standard Class, First Class, Second Class]),
(Customer ID:TEXT, Examples: [MB-18085, SV-20365, MM-17920]),
(Region:TEXT, Examples: [East]),
(Product ID:TEXT, Examples: [OFF-AR-10003478, FUR-FU-10000010, OFF-PA-10002947]),
(Sales:REAL, Examples: [19.536, 9.94, 37.408]),
(Quantity:INTEGER, Examples: [3, 2, 7]),
(Discount:REAL, Examples: [0.2, 0.0, 0.7]),
(Profit:REAL, Examples: [4.884, 3.0814, 13.0928])
]
# Table: central_superstore
[
(Row ID:INTEGER, Primary Key, Examples: [1, 2, 3]),
(Order ID:TEXT, Examples: [CA-2011-103800, CA-2011-112326, CA-2011-105417]),
(Order Date:DATE, Examples: [2013-01-03]),
(Ship Date:DATE, Examples: [2013-01-07]),
(Ship Mode:TEXT, Examples: [Standard Class, First Class, Second Class]),
(Customer ID:TEXT, Examples: [DP-13000, PO-19195, VS-21820]),
(Region:TEXT, Examples: [Central]),
(Product ID:TEXT, Examples: [OFF-PA-10000174, OFF-LA-10003223, OFF-ST-10002743]),
(Sales:REAL, Examples: [16.448, 11.784, 272.736]),
(Quantity:INTEGER, Examples: [2, 3, 7]),
(Discount:REAL, Examples: [0.2, 0.8, 0.6]),
(Profit:REAL, Examples: [5.5512, 4.2717, -64.7748])
]
# Table: product
[
(Product ID:TEXT, Primary Key, Examples: [FUR-BO-10000112, FUR-BO-10000330, FUR-BO-10000362]),
(Product Name:TEXT),
(Category:TEXT, Examples: [Furniture, Office Supplies, Technology]),
(Sub-Category:TEXT, Examples: [Bookcases, Chairs, Furnishings]),
(Region:TEXT, Primary Key, Examples: [Central, South, West])
]
【Foreign keys】
south_superstore.Customer ID=people.Customer ID
south_superstore.Region=people.Region
south_superstore.Product ID=product.Product ID
south_superstore.Region=product.Region
west_superstore.Customer ID=people.Customer ID
west_superstore.Region=people.Region
west_superstore.Product ID=product.Product ID
west_superstore.Region=product.Region
east_superstore.Customer ID=people.Customer ID
east_superstore.Region=people.Region
east_superstore.Product ID=product.Product ID
east_superstore.Region=product.Region
central_superstore.Customer ID=people.Customer ID
central_superstore.Region=people.Region
central_superstore.Product ID=product.Product ID
central_superstore.Region=product.Region

    【Question】
    Among the customers from Chicago, Illinois, what is the highest quantity of products bought in a single order? from Chicago refers to City = 'Chicago'; Illinois refers to State = 'Illinois'; highest quantity refers to max(Quantity)

    【Evidence】
    from Chicago refers to City = 'Chicago'; Illinois refers to State = 'Illinois'; highest quantity refers to max(Quantity)

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

SQL: SELECT T1.Quantity FROM west_superstore AS T1 INNER JOIN east_superstore AS T2 ON T1.`Customer ID` = T2.`Customer ID` INNER JOIN central_superstore AS T3 ON T3.`Customer ID` = T2.`Customer ID` INNER JOIN south_superstore AS T4 ON T4.`Customer ID` = T3.`Customer ID` INNER JOIN people AS T5 ON T5.`Customer ID` = T4.`Customer ID` WHERE T5.City = 'Chicago' AND T5.State = 'Illinois' ORDER BY T1.Quantity DESC LIMIT 1