mysql三表内连接语句

SELECT column_name(s)
FROM table1
INNER JOIN table2 ON table1.column = table2.column
INNER JOIN table3 ON table2.column = table3.column;

SELECT orders.order_id, customers.customer_name, products.product_name
FROM orders
INNER JOIN customers ON orders.customer_id = customers.customer_id
INNER JOIN products ON orders.product_id = products.product_id;

-- 错误的连接条件
SELECT orders.order_id, customers.customer_name, products.product_name
FROM orders
INNER JOIN customers ON orders.order_id = customers.customer_id
INNER JOIN products ON orders.product_id = products.product_id;

-- 正确的连接条件
SELECT orders.order_id, customers.customer_name, products.product_name
FROM orders
INNER JOIN customers ON orders.customer_id = customers.customer_id
INNER JOIN products ON orders.product_id = products.product_id;

-- 创建索引
CREATE INDEX idx_customer_id ON customers(customer_id);
CREATE INDEX idx_product_id ON products(product_id);

-- 分页查询
SELECT orders.order_id, customers.customer_name, products.product_name
FROM orders
INNER JOIN customers ON orders.customer_id = customers.customer_id
INNER JOIN products ON orders.product_id = products.product_id
LIMIT 10 OFFSET 0;