Mysql将多表合并为一张表查询

需求：将销售订单和采购订单相同字段合并成一张表然后进行分页查询。

列如采购数据：

	SELECT contract_id,group_id,total_quantity,total_amount,created FROM 	scm_purchase_order ORDER BY created DESC LIMIT 0,15

结果：

销售数据：

	SELECT contract_id,group_id,total_quantity,total_amount,created FROM 	scm_sale_order ORDER BY created DESC LIMIT 0,15

结果：

然后将两张表数据合并为一张表分页查询：

SELECT
contract_id AS 合同号,
group_id AS 部门id,
total_quantity AS 数量,
total_amount AS 金额,
created AS 时间
FROM
	(
		SELECT
contract_id,
group_id,
total_quantity,
total_amount,
created
		FROM
			scm_purchase_order
		UNION
			SELECT
contract_id,
group_id,
total_quantity,
total_amount,
created
			FROM
				scm_sale_order
			
	) AS tb ORDER BY created DESC LIMIT 0,15

得出结果：