Parsing JSON in SQL Server - sql

Question

Referring to the example provided by Microsoft:
DECLARE #json NVARCHAR(MAX)
SET #json =
N'[
{ "id" : 2,"info": { "name": "John", "surname": "Smith" }, "age": 25 },
{ "id" : 5,"info": { "name": "Jane", "surname": "Smith" }, "dob": "2005-11-04T12:00:00" }
]'
SELECT *
FROM OPENJSON(#json)
WITH (id int 'strict $.id',
firstName nvarchar(50) '$.info.name', lastName nvarchar(50) '$.info.surname',
age int, dateOfBirth datetime2 '$.dob')
when the JSON data has an array inside, for example:
DECLARE #json NVARCHAR(MAX)
SET #json =
N'[
{ "id" : 2,"info": { "name": "John", "surname": "Smith" },
"Phones": ["123","345","678"] // like here
}
]'
Is there any way to join the array on the parsed data to get something like this:
Id First Name Last Name Phone
2 John Smith 123
2 John Smith 345
2 John Smith 678

Answer 1

OUTER APPLY is your friend here. Let's mix up both kinds of rows for good measure.
DECLARE #json NVARCHAR(MAX)
SET #json = N'
[
{
"id": 2,
"info": {
"name": "John",
"surname": "Smith"
},
"age": 25,
"Phones": [
"123",
"345",
"678"
]
},
{
"id": 5,
"info": {
"name": "Jane",
"surname": "Smith"
},
"dob": "2005-11-04T12:00:00"
}
]'
SELECT id, [name], [surname], age, dateOfBirth, number
FROM (
SELECT *
FROM OPENJSON(#json)
WITH (
id INT 'strict $.id',
[name] NVARCHAR(50) '$.info.name',
[surname] NVARCHAR(50) '$.info.surname',
age INT,
dateOfBirth DATETIME2 '$.dob',
Phones NVARCHAR(MAX) AS JSON
)
) AS people
OUTER APPLY OPENJSON(Phones)
WITH (
number NVARCHAR(50) '$'
)
Result:
+----+------+---------+------+-----------------------------+--------+
| id | name | surname | age | dateOfBirth | number |
+----+------+---------+------+-----------------------------+--------+
| 2 | John | Smith | 25 | NULL | 123 |
| 2 | John | Smith | 25 | NULL | 345 |
| 2 | John | Smith | 25 | NULL | 678 |
| 5 | Jane | Smith | NULL | 2005-11-04 12:00:00.0000000 | NULL |
+----+------+---------+------+-----------------------------+--------+

Answer 2

Well, you can always do something like this:
SELECT ID, FirstName, LastName, value
FROM OPENJSON(#json)
WITH(ID int '$.id',
FirstName nvarchar(50) '$.info.name',
LastName nvarchar(50) '$.info.surname',
Phones nvarchar(max) '$.Phones' AS Json)
CROSS APPLY OPENJSON(Phones)
Hope this helps.

Answer 3

You will have to do it in two passes:
Extract for each person data and leaving array of phone numbers as JSON
Use CROSS/OUTER APPLY to parse array of phone numbers for each person and join result together
Something like this:
DECLARE #json NVARCHAR(MAX)
SET #json =
N'[
{ "id" : 2,"info": { "name": "John", "surname": "Smith" }, "Phones": ["123","345","678"] },
{ "id" : 3,"info": { "name": "Jane", "surname": "Smith" }, "Phones": ["321","543"] }
]';
WITH CTE AS (
SELECT id, firstName, lastName, phones
FROM OPENJSON(#json)
WITH (
id INT 'strict $.id',
firstName NVARCHAR(50) '$.info.name',
lastName NVARCHAR(50) '$.info.surname',
phones NVARCHAR(MAX) '$.Phones' AS JSON
)
)
SELECT c.id, c.firstName, c.lastName, p.value as phone
FROM CTE c
CROSS APPLY OPENJSON(c.phones) p

Answer 4

You can use C# library
https://www.dotnet4techies.com/2018/07/convert-json-to-sql-format-using-csharp.html
It is a powerful tool and it maintains sql relationships from your Json if it has nested levels.