Linq How to run queries in chunks - sql-server

Question

I have bundle of delete queries like following :-
DELETE FROM [Entry]
WHERE CompanyId = 1
AND EmployeeId IN (3, 4, 6, 7, 14, 17, 20, 21, 22,....100 more)
AND Entry_Date = '2016-12-01'
AND Entry_Method = 'I'
SO in my code, i run this list of queries as below :-
using (var ctx = new ApplicationDbContext(schemaName))
{
foreach (var item in queries)
{
ctx.Database.ExecuteSqlCommand(item);
}
}
But due to the large number of queries executing it creates a lock on sql, so i decided to execute the queries in chunk, so i found the below code :-
SET ROWCOUNT 500
delete_more:
DELETE FROM [Entry]
WHERE CompanyId = 1
AND EmployeeId IN (3, 4, 6, 7, 14, 17, 20, 21, 22,....100 more)
AND Entry_Date = '2016-12-01'
AND Entry_Method = 'I'
IF ##ROWCOUNT > 0 GOTO delete_more
SET ROWCOUNT 0
Now the problem is How do i run this thing as i was running it previously through ctx.Database.ExecuteSqlCommand?
What is the way i can run this chunk query code in Linq?

Answer 1

I would create a SQL Server stored procedure that get the employee ids as a parameter. Let's call it 'sp_deleteEmployees' with the param #ids
Then in C# you create a string on the ids
string idsList = "3, 4, 6, 7, 14, 17, 20, 21, 22"
context.Database.ExecuteSqlCommand("usp_CreateAuthor #ids={0} ", idsList);
EDIT
Sorry, I guess I didn't understand the problem. If you need to delete the employees in chunk you can split the list of employee with this
public static List<IEnumerable<T>> Partition<T>(this IEnumerable<T> source, int length)
{
var count = source.Count();
var numberOfPartitions = count / length + ( count % length > 0 ? 1 : 0);
List<IEnumerable<T>> result= new List<IEnumerable<T>>();
for (int i = 0; i < numberOfPartitions; i++)
{
result.Add(source.Skip(length*i).Take(length));
}
return result;
}
You can use this method to split the list to small chunks and delete them one chunk at a time