### Database Schema
CREATE TABLE people
(
    "Customer ID"   TEXT,
    "Customer Name" TEXT,
    Segment         TEXT,
    Country         TEXT,
    City            TEXT,
    State           TEXT,
    "Postal Code"   INTEGER,
    Region          TEXT,
    primary key ("Customer ID", Region)
)

CREATE TABLE product
(
    "Product ID"   TEXT,
    "Product Name" TEXT,
    Category       TEXT,
    "Sub-Category" TEXT,
    Region         TEXT,
    primary key ("Product ID", Region)
)

CREATE TABLE central_superstore
(
    "Row ID"      INTEGER
            primary key,
    "Order ID"    TEXT,
    "Order Date"  DATE,
    "Ship Date"   DATE,
    "Ship Mode"   TEXT,
    "Customer ID" TEXT,
    Region        TEXT,
    "Product ID"  TEXT,
    Sales         REAL,
    Quantity      INTEGER,
    Discount      REAL,
    Profit        REAL,
    foreign key ("Customer ID", Region) references people("Customer ID",Region),
    foreign key ("Product ID", Region) references product("Product ID",Region)
)

CREATE TABLE east_superstore
(
    "Row ID"      INTEGER
            primary key,
    "Order ID"    TEXT,
    "Order Date"  DATE,
    "Ship Date"   DATE,
    "Ship Mode"   TEXT,
    "Customer ID" TEXT,
    Region        TEXT,
    "Product ID"  TEXT,
    Sales         REAL,
    Quantity      INTEGER,
    Discount      REAL,
    Profit        REAL,
    foreign key ("Customer ID", Region) references people("Customer ID",Region),
    foreign key ("Product ID", Region) references product("Product ID",Region)
)

CREATE TABLE south_superstore
(
    "Row ID"      INTEGER
            primary key,
    "Order ID"    TEXT,
    "Order Date"  DATE,
    "Ship Date"   DATE,
    "Ship Mode"   TEXT,
    "Customer ID" TEXT,
    Region        TEXT,
    "Product ID"  TEXT,
    Sales         REAL,
    Quantity      INTEGER,
    Discount      REAL,
    Profit        REAL,
    foreign key ("Customer ID", Region) references people("Customer ID",Region),
    foreign key ("Product ID", Region) references product("Product ID",Region)
)

CREATE TABLE west_superstore
(
    "Row ID"      INTEGER
            primary key,
    "Order ID"    TEXT,
    "Order Date"  DATE,
    "Ship Date"   DATE,
    "Ship Mode"   TEXT,
    "Customer ID" TEXT,
    Region        TEXT,
    "Product ID"  TEXT,
    Sales         REAL,
    Quantity      INTEGER,
    Discount      REAL,
    Profit        REAL,
    foreign key ("Customer ID", Region) references people("Customer ID",Region),
    foreign key ("Product ID", Region) references product("Product ID",Region)
)

### Question
Calculate the percentage of ordered office supplies products in the central and the south superstore.

### Hint
office supplies products refers to Category = 'Office Supplies'; central refers to Region = 'Central'; south superstore refers to Region = 'South'; percentage = divide(SUM(Product ID where Category = 'Office Supplies'), count(Product ID)) * 100 where Region = 'Central' OR Region = 'South'

### SQL
SELECT CAST(SUM(CASE  WHEN T3.Category = 'Office Supplies' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T3.Category) FROM people AS T1 INNER JOIN central_superstore AS T2 ON T1.`Customer ID` = T2.`Customer ID` INNER JOIN product AS T3 ON T3.`Product ID` = T2.`Product ID`