分组拼接GROUP_CONCAT(expr)

• group_concat函数
  • 实现分组查询之后的数据进行合并，并返回一个字符串结果。
  • 用于将多个字符串拼接成一个字符串。
  • MySql默认的最大拼接长度为1024个字节

应用场景：按照产品编码分组，获取生效策略

 

SELECT
	product_no,
	group_concat(
		CONCAT(
			"[",(
			CASE
					WHEN strategy_type = 1 THEN
					"通信计划" 
					WHEN strategy_type = 2 THEN
					"资费计划" 
					WHEN strategy_type = 3 THEN
					"PCRF策略" 
					WHEN strategy_type = 4 THEN
					"收费事件" 
					WHEN strategy_type = 6 THEN
					"Panabit策略" 
					WHEN strategy_type = 7 THEN
					"捷德策略" ELSE "" 
				END 
				),
				"]",
				strategy_id 
			) SEPARATOR ',' 
		) AS strategy_info 
	FROM
		t_data_product_strategy 
	WHERE
		type = 1 
GROUP BY
	product_no