mysql 使用记录

mapper入参List

• 使用mybatis的foreach迭代

SELECT
	* 
FROM
	test_ids 
WHERE
	1 = 1 
	< IF test = "hosAppCodes != null and hosAppCodes.size > 0" > 
		AND id IN < foreach collection = "ids" INDEX = "index" item = "id" OPEN = "(" SEPARATOR = "," CLOSE = ")" > #{id}</ foreach > 
	</ IF >

• 将List转换为list结构的字符串再使用in,此时mapper中的入参应为String,例如

['1', '2', '3']

SELECT
	* 
FROM
	test_ids 
WHERE
	1 = 1 
	< IF test = "hosAppCodes != null and hosAppCodes != '' " > 
		AND id IN (#{ids})
	</ IF >

UNION 与 UNION All区别

union 会去重，union all 不会