Update Table using SQL Cursor

Question

I am trying to update fields in a table using a cursor but the update is not happening and I do not know why. Here is my SQL query:

DECLARE @EmployeeCompanyId int

SELECT DISTINCT  EmployeeCompanyId
FROM [dbo].[tbl_Company_Employee_Contacts]


OPEN MY_CURSOR

FETCH NEXT FROM MY_CURSOR INTO @EmployeeCompanyId

WHILE @@FETCH_STATUS = 0
BEGIN 
    UPDATE [dbo].[tbl_Company_Employee_Contacts]
    SET City = (SELECT TOP 1 Phone 
                FROM [dbo].[tbl_Company_Employee_Contacts]
                WHERE EmployeeCompanyId = @EmployeeCompanyId 
                 AND City IS NOT NULL)
    WHERE EmployeeCompanyId = @EmployeeCompanyId 
       AND City IS NOT NULL

    FETCH NEXT FROM MY_CURSOR INTO @EmployeeCompanyId
END

CLOSE MY_CURSOR

Table was created with a single piece of contact information per record. I am trying to consolidate all info into one record so that I can delete the others:

Answer 1

Something you could do is the following. you haven't provided any concrete sample data and desired results so this is just a mock-up but should give you something to work with, and no cursor in sight.

/* sample data */
create table T (id int, EmployeeCompanyId int, Phone varchar(20), Street varchar(50))
insert into T values
(1,     10,'1234567890', null),
(1202,  10,'1234567890', null),
(78086, 10, null, 'Larose'),
(144887,10, null, 'Larose')

select * from T;

/* Update the highest ID row for each employee with data for each column*/
with u as (
    select Max(Id) Id, Max(Phone) Phone, Max(Street) Street
    from T
    group by EmployeeCompanyId
)
update t set
    t.phone=u.phone,
    t.street=u.street
from u
join T  on t.Id=u.Id

select * from T

/* delete all redundant rows for each employee */
/* This keeps the highest ID, if you want to put all data on the lowest ID, reverse the criteria accordingly */


with u as (
select EmployeeCompanyId, id, Row_Number() over (partition by EmployeeCompanyId order by id desc) rn
from t
)
delete from t
from u join t on t.Id=u.Id
where u.rn>1

select * from T

Answer 2

As other people have stated in the comments, I don't know why the CURSOR is even necessary here. But the problem with your code above is that you didn't DECLARE the CURSOR first in your initial SELECT .

DECLARE @EmployeeCompanyId int

DECLARE MY_CURSOR CURSOR FOR
    SELECT DISTINCT  EmployeeCompanyId
    FROM [dbo].[tbl_Company_Employee_Contacts]


OPEN MY_CURSOR

FETCH NEXT FROM MY_CURSOR INTO @EmployeeCompanyId

WHILE @@FETCH_STATUS = 0
BEGIN 
    UPDATE [dbo].[tbl_Company_Employee_Contacts]
    SET City = (SELECT TOP 1 Phone 
                FROM [dbo].[tbl_Company_Employee_Contacts]
                WHERE EmployeeCompanyId = @EmployeeCompanyId 
                 AND City IS NOT NULL)
    WHERE EmployeeCompanyId = @EmployeeCompanyId 
       AND City IS NOT NULL

    FETCH NEXT FROM MY_CURSOR INTO @EmployeeCompanyId
END

CLOSE MY_CURSOR