sql语句中新增自定义getJsonValue函数

在sql执行区执行一下语句，即可新增函数，属于参数格式getJsonValue('json包含的字段名',json字符串对应的字段名)

CREATE FUNCTION `getJsonValue`(pKeyName VARCHAR(64),pColName mediumtext) RETURNS varchar(2000) CHARSET utf8 COLLATE utf8_bin
return 
substr(pColName,
locate(concat('"',upper(pKeyName),'":"'),upper(pColName))+length(concat('"',upper(pKeyName),'":"')),
case when locate('","',substr(upper(pColName),locate(concat('"',upper(pKeyName),'":"'),upper(pColName))))>0 then (locate('","',substr(upper(pColName),locate(concat('"',upper(pKeyName),'":"'),upper(pColName))+length(concat('"',upper(pKeyName),'":"'))))-1)
else locate('"}',substr(upper(pColName),locate(concat('"',upper(pKeyName),'":"'),upper(pColName))+length(concat('"',upper(pKeyName),'":"'))))-1 end )