背景：

方法一：不借助于自定义函数实现 

方法二：不借助于自定义函数实现 

方法三：借助于自定义函数实现

背景：

表tmp.biz中只有id , biz_info 两个字段，目的是解析出字段biz_info里，key值对应的value值数据，以供需求方使用。

原始要清洗解析的数据 , 如下:

id='44788'时biz_info字段原样：
[{"visitHosCode":"H107201","visitFirstDeptName":"内科","visitSecondDeptCode":"4010504","visitSecondDeptName":"肝胆胰中医特色门诊","priority":50,"visitTimeText":"周二上午"},{"visitHosCode":"H107201","visitFirstDeptName":"内科","visitSecondDeptCode":"4010501","visitSecondDeptName":"脾胃病科一区门诊","priority":60,"visitTimeText":"周三上午"},{"visitHosCode":"H107201","visitFirstDeptName":"感染科","visitSecondDeptCode":"4140001","visitSecondDeptName":"肝炎门诊","priority":50,"visitTimeText":""},{"visitHosCode":"H107201","visitFirstDeptName":"国际部","visitSecondDeptCode":"G401501","visitSecondDeptName":"国际部脾胃病科一区","priority":5,"visitTimeText":"周二下午"}
]

方法一：不借助于自定义函数实现 

  原来1行数据，现在变为多行【因为这种方式有几个花括号,就变为几行 ; " 行数=花括号数，列数=1个花括号中key的个数 "】;
  有使用lateral view explode函数;

selectid,get_json_object(t3,'$.visitHosCode') as visitHosCode,get_json_object(t3,'$.visitFirstDeptName') as visitFirstDeptName,get_json_object(t3,'$.visitSecondDeptCode') as visitSecondDeptCode,get_json_object(t3,'$.visitSecondDeptName') as visitSecondDeptName,get_json_object(t3,'$.priority') as priority,get_json_object(t3,'$.visitTimeText') as visitTimeText
from
(selectid,if(item not like'%}%',concat(item,'}'),item) t3 --调整成正常的json串【因为item字段会有{ 或 ,{ 样式的数据】from (select id,biz_info,regexp_replace(biz_info,'\\]','')t1                            --去除左括号,regexp_replace(regexp_replace(biz_info,'\\]',''),'\\[','')t2   --去除右括号from tmp.biz)a lateral view explode(split(t2,'},'))t as item
)b
;

查询出的结果值：

id	    visithoscode	 visitfirstdeptname	   visitseconddeptcode    visitseconddeptname	 priority   visittimetext
44788   H107201	         内科	               4010504	              肝胆胰中医特色门诊	     50	         周二上午
44788   H107201	         内科	               4010501	              脾胃病科一区门诊	         60	         周三上午
44788   H107201	         感染科	               4140001	              肝炎门诊	             50	          
44788   H107201	         国际部	               G401501	              国际部脾胃病科一区	     5	         周二下午

 方法二：不借助于自定义函数实现 

   
  原来1行数据，现在还是为1行【因为没有使用lateral view explode函数】;
  需写多个get_json_object()函数;

select id,get_json_object(biz_info, "$.[0].visitHosCode")        as visitHosCode_1,get_json_object(biz_info, "$.[0].visitFirstDeptName")  as visitFirstDeptName_1,get_json_object(biz_info, "$.[0].visitSecondDeptCode") as visitSecondDeptCode_1,get_json_object(biz_info, "$.[0].visitSecondDeptName") as visitSecondDeptName_1,get_json_object(biz_info, "$.[0].priority")            as priority_1,get_json_object(biz_info, "$.[0].visitTimeText")       as visitTimeText_1,get_json_object(biz_info, "$.[1].visitHosCode")        as visitHosCode_2,get_json_object(biz_info, "$.[1].visitFirstDeptName")  as visitFirstDeptName_2,get_json_object(biz_info, "$.[1].visitSecondDeptCode") as visitSecondDeptCode_2,get_json_object(biz_info, "$.[1].visitSecondDeptName") as visitSecondDeptName_2,get_json_object(biz_info, "$.[1].priority")            as priority_2,get_json_object(biz_info, "$.[1].visitTimeText")       as visitTimeText_2,get_json_object(biz_info, "$.[2].visitHosCode")        as visitHosCode_3,get_json_object(biz_info, "$.[2].visitFirstDeptName")  as visitFirstDeptName_3,get_json_object(biz_info, "$.[2].visitSecondDeptCode") as visitSecondDeptCode_3,get_json_object(biz_info, "$.[2].visitSecondDeptName") as visitSecondDeptName_3,get_json_object(biz_info, "$.[2].priority")            as priority_3,get_json_object(biz_info, "$.[2].visitTimeText")       as visitTimeText_3,get_json_object(biz_info, "$.[3].visitHosCode")        as visitHosCode_4,get_json_object(biz_info, "$.[3].visitFirstDeptName")  as visitFirstDeptName_4,get_json_object(biz_info, "$.[3].visitSecondDeptCode") as visitSecondDeptCode_4,get_json_object(biz_info, "$.[3].visitSecondDeptName") as visitSecondDeptName_4,get_json_object(biz_info, "$.[3].priority")            as priority_4,get_json_object(biz_info, "$.[3].visitTimeText")       as visitTimeText_4
from tmp.biz

 查询出的结果值： 

id	    visithoscode	 visitfirstdeptname	   visitseconddeptcode    visitseconddeptname	 priority   visittimetext
44788   H107201	         内科	               4010504	              肝胆胰中医特色门诊	     50	         周二上午
44788   H107201	         内科	               4010501	              脾胃病科一区门诊	         60	         周三上午
44788   H107201	         感染科	               4140001	              肝炎门诊	             50	          
44788   H107201	         国际部	               G401501	              国际部脾胃病科一区	     5	         周二下午

缺点：需要写多个get_json_object()函数

方法三：借助于自定义函数实现

 
  原来1行数据，现在变为多行【因为这种方式有几个花括号,就变为几行 ; " 行数=花括号数，列数=1个花括号中key的个数 "】;
  有使用lateral view explode 与 lateral view json_tuple函数; hue查询工具中不能运行 , 需要再Airflow调度中才能运行;
 

CREATE TABLE if not exists `tmp.biz_result`(`id` string, `visithoscode` string, `visitfirstdeptname` string, `visitseconddeptcode` string, `visitseconddeptname` string, `priority` string, `visittimetext` string
)COMMENT '解析后的结果表'
stored as parquet
location '/hive/xxx/tmp.db/biz_result' 
TBLPROPERTIES ('parquet.compression'='SNAPPY');--需要手写自定UDF , 之后调用自定义的UDF函数
add jar /home/...路径/udf/tmp/json_array.jar;
create temporary function json_array as 'com.benmu.udf.Json_array';insert overwrite table tmp.biz_result
select
id,visitHosCode,visitFirstDeptName,visitSecondDeptCode,visitSecondDeptName,priority,visitTimeText
from
(
select 
id,biz_info
from
tmp.biz
)a
lateral view explode(json_array(biz_info)) t as item
lateral view json_tuple(item,'visitHosCode','visitFirstDeptName','visitSecondDeptCode','visitSecondDeptName','priority','visitTimeText')t1 as visitHosCode,visitFirstDeptName,visitSecondDeptCode,visitSecondDeptName,priority,visitTimeText
;

查询出的结果值： 

hive> select * from tmp.biz_result;id	    visithoscode	 visitfirstdeptname	   visitseconddeptcode    visitseconddeptname	 priority   visittimetext
44788   H107201	         内科	               4010504	              肝胆胰中医特色门诊	     50	         周二上午
44788   H107201	         内科	               4010501	              脾胃病科一区门诊	         60	         周三上午
44788   H107201	         感染科	               4140001	              肝炎门诊	             50	          
44788   H107201	         国际部	               G401501	              国际部脾胃病科一区	     5	         周二下午