Json data flattening on snowflake - snowflake-cloud-data-platform

Question

I'm trying to flatten below Json data on snowflake :
Json Data :
{
"empDetails": [
{
"kind": "person",
"fullName": "John Doe",
"age": 22,
"gender": "Male",
"phoneNumber": {
"areaCode": "206",
"number": "1234567"
},
"children": [
{
"name": "Jane",
"gender": "Female",
"age": "6"
},
{
"name": "John",
"gender": "Male",
"age": "15"
}
],
"citiesLived": [
{
"place": "Seattle",
"yearsLived": [
"1995"
]
},
{
"place": "Stockholm",
"yearsLived": [
"2005"
]
}
]
},
{
"kind": "person",
"fullName": "Mike Jones",
"age": 35,
"gender": "Male",
"phoneNumber": {
"areaCode": "622",
"number": "1567845"
},
"children": [
{
"name": "Earl",
"gender": "Male",
"age": "10"
},
{
"name": "Sam",
"gender": "Male",
"age": "6"
},
{
"name": "Kit",
"gender": "Male",
"age": "8"
}
],
"citiesLived": [
{
"place": "Los Angeles",
"yearsLived": [
"1989",
"1993",
"1998",
"2002"
]
},
{
"place": "Washington DC",
"yearsLived": [
"1990",
"1993",
"1998",
"2008"
]
},
{
"place": "Portland",
"yearsLived": [
"1993",
"1998",
"2003",
"2005"
]
},
{
"place": "Austin",
"yearsLived": [
"1973",
"1998",
"2001",
"2005"
]
}
]
},
{
"kind": "person",
"fullName": "Anna Karenina",
"age": 45,
"gender": "Female",
"phoneNumber": {
"areaCode": "425",
"number": "1984783"
},
"citiesLived": [
{
"place": "Stockholm",
"yearsLived": [
"1992",
"1998",
"2000",
"2010"
]
},
{
"place": "Russia",
"yearsLived": [
"1998",
"2001",
""
]
},
{
"place": "Austin",
"yearsLived": [
"1995",
"1999"
]
}
]
}
]
}
I'm able to flatten the most of the data except for column/array years Lived,
for last column I'm getting null values.
below is what I have tried so far :
select empd.value:kind,
empd.value:fullName,
empd.value:age,
empd.value:gender,
empd.value:phoneNumber,
empd.value:phoneNumber.areaCode,
empd.value:phoneNumber.number ,
empd.value:children,
chldrn.value:name,
chldrn.value:gender,
chldrn.value:age,
city.value:place,
yr.value:yearsLived
from my_json emp,
lateral flatten(input=>emp.Json_data:empDetails) empd ,
lateral flatten(input=>empd.value:children, OUTER => TRUE) chldrn,
lateral flatten(input=>empd.value:citiesLived) city,
lateral flatten(input=>city.value:yearsLived) yr -- not getting data for
this array
can someone help me understand why I'm getting null values for yearsLived array ? I'm not sure if I'm missing anything here

Answer 1

Your query returns the column
yr.value:yearsLived
as if yr.value were an OBJECT with fields.
But you have already expanded the yearsLived field in the line
lateral flatten(input=>city.value:yearsLived) yr
so yr.value is really just a VARIANT containing the year. You can leave it as such—or perhaps wrap it in TO_NUMBER or TO_VARCHAR to have a more precise type.

Answer 2

Why don't you try this out.
create or replace table json_tab as
select parse_json('{ "place": "Austin","yearsLived": [ "1995","1999"]}') as years
select years:yearsLived[0]::int from json_tab
Since your JSON data is an array, you need to access the elements via index if you would like to get specific values or use any array function to explode it.
with flatten function
select years, v.value::string
from json_tab,
lateral flatten(input =>years:yearsLived ) v;