LOOP Through JSON Data and update query in SQL Sever

Question

I have a JSON array as below

    [
      {
        "CRT_FIRST_NAME": "abc",
        "CRT_EMAIL": "abc@gmail.com",
        "CRT_ID": 60
      },
      {
        "CRT_FIRST_NAME": "pqr",
        "CRT_EMAIL": "pqr@gmail.com",
        "CRT_ID": 61
      },
      {
        "CRT_FIRST_NAME": "sample",
        "CRT_EMAIL": "sample@gmail.com",
        "CRT_ID": 62
      }
    ]

I am passing it and executing a stored procedure save_employee_data as below

 exec save_employee_data '[{"CRT_FIRST_NAME": "abc","CRT_EMAIL": "abc@gmail.com","CRT_ID": 60},{"CRT_FIRST_NAME": "pqr","CRT_EMAIL": "pqr@gmail.com","CRT_ID": 61},{"CRT_FIRST_NAME": "sample","CRT_EMAIL": "sample@gmail.com","CRT_ID": 62}]'

And my stored procedure is as below

    CREATE PROCEDURE [dfed].[save_employee_data] 
    @jsondata nvarchar(max)
    AS
    DECLARE

    @CRTID_FETCH INT,
    @CRT_FIRST_NAME_FETCH  VARCHAR(250),
    @CRT_EMAIL_FETCH VARCHAR(250)

    BEGIN
        SELECT @CRT_FIRST_NAME_FETCH=CRT_FIRST_NAME, @CRT_EMAIL_FETCH=CRT_EMAIL, @CRTID_FETCH=CRT_ID FROM  
         OPENJSON ( @jsondata )  
        WITH (   
                      CRT_FIRST_NAME   varchar(200) '$.CRT_FIRST_NAME' ,
                      CRT_EMAIL varchar(200) '$.CRT_EMAIL',
                      CRT_ID varchar(200) '$.CRT_ID'
         ) 

        UPDATE employees SET email_staff = @CRT_EMAIL_FETCH WHERE CRT_ID = @CRTID_FETCH
    END

Here the update query is not working. I am trying loop my JSON data and fetch the CRT_EMAIL, CRT_FIRST_NAME, CRT_ID values from json data and based on these values I am trying to update email_staff column with CRT_EMAIL value for its respective column i.e primary key CRT_ID

But the update query is not working. Is this the correct way of looping JSON data?

Answer 1

Just join the JSON data to the employees table and update the results. Like this

with n as
(
      SELECT CRT_FIRST_NAME, CRT_EMAIL, CRT_ID 
      FROM OPENJSON ( @jsondata )  
         WITH (   
                CRT_FIRST_NAME   varchar(200) '$.CRT_FIRST_NAME' ,
                CRT_EMAIL varchar(200) '$.CRT_EMAIL',
                CRT_ID varchar(200) '$.CRT_ID'
              ) 
), q as
(
   select n.CRT_EMAIL, e.email_staff , e.crt_id
   from n 
   join employees e
     on n.CRT_ID = e.CRT_ID
)
--select * from q;
update q set email_staff = CRT_EMAIL; 

If you want to loop over the json data you can use a cursor. EG

DECLARE C CURSOR LOCAL FOR 
    SELECT CRT_FIRST_NAME, CRT_EMAIL, CRT_ID 
    FROM  OPENJSON ( @jsondata )  
    WITH (   
                  CRT_FIRST_NAME   varchar(200) '$.CRT_FIRST_NAME' ,
                  CRT_EMAIL varchar(200) '$.CRT_EMAIL',
                  CRT_ID varchar(200) '$.CRT_ID'
     ); 
OPEN C;

FETCH NEXT FROM C INTO  @CRT_FIRST_NAME, @CRT_EMAIL, @CRT_ID; 
WHILE @@FETCH_STATUS = 0      
BEGIN

    UPDATE employees SET email_staff = @CRT_EMAIL WHERE CRT_ID = @CRT_ID;

    FETCH NEXT FROM C INTO  @CRT_FIRST_NAME, @CRT_EMAIL, @CRT_ID;                 
END

CLOSE C;
DEALLOCATE C;