请在 phpMyAdmin 中执行以下 SQL 以建立核心表：
CREATE TABLE IF NOT EXISTS users (
id VARCHAR(50) PRIMARY KEY,
name VARCHAR(255),
email VARCHAR(255) UNIQUE,
password VARCHAR(255),
status VARCHAR(20) DEFAULT 'ACTIVE',
role VARCHAR(20) DEFAULT 'USER',
join_date DATETIME
);
CREATE TABLE IF NOT EXISTS receipts (
id VARCHAR(50) PRIMARY KEY,
user_id VARCHAR(50),
merchant_name VARCHAR(255),
receipt_date DATE,
total_amount DECIMAL(10,2),
tax_amount DECIMAL(10,2),
qr_url TEXT,
portal_type VARCHAR(50),
is_converted TINYINT(1),
timestamp BIGINT
);