I want Run the infinite loop - sql-server

Question

1-Using SQL Server 2014, how can I edit this code?
2-If the condition is not met Return to condition check again
3-If the check condition is correct - go to Next
4-When you finish code Return to first condition check again
I want Run the infinite loop
Please see the picture for clarificationenter image description here
if not exists (
select top 1 1
from sms.dbo.m_link
where link_check = 0
)RETURN
WAITFOR DELAY '00:00:05'
INSERT INTO sms.dbo.M_Out (MessageTo ,MessageType ,Gateway ,UserId)
select top 1 1 link_MessageTo ,link_MessageType ,link_Gateway ,link_UserId
from sms.dbo.m_link
where link_check = 0
WAITFOR DELAY '00:00:10'

Answer 1

With your image and the update to your question, it looks like you are queuing records into the m_link table, and wanting to insert one record at a time into the m_out table? I'm not sure this is the best approach but to answer your question, you could use a While Loop which is often a dirty word in SQL Server.
The code logic you currently have is off, to sql it reads:
if not exists (no record to be inserted)
wait a few seconds
insert the first record from the table that doesn't have any records into
the outgoing table. (illogical)
wait a few more seconds
on the other hand, if a record does exists SQL does nothing, you haven't told it what you want to do
My suggestion of using the while loop is based on being able to complete the task as you have presented it, I am hesitant to suggest it as I doubt it is the best approach, however with out additional information the following code should accomplish what it seems you are trying to do.
without further ado:
set nocount on;
--| Supporting Tables
declare #delete as table (
m_linkID int not null
);
declare #m_Out as table (
m_OutID int identity(73,1) not null primary key clustered
, m_linkID int not null
, link_MessageTo nvarchar(255) not null
, link_MessageType int not null
, link_Gateway int not null
, link_UserID int not null
);
declare #m_link as table (
m_linkID int identity(1,1) not null primary key clustered
, link_MessageTo nvarchar(255) not null
, link_MessageType int not null
, link_Gateway int not null
, link_UserID int not null
);
--| populate the m_link table with example records
insert into #m_link (link_MessageTo, link_MessageType, link_Gateway, link_UserID)
select 'Message One', 1, 42, 666 union all
select 'Message Two', 1, 57, 99;
--| show the inserted records
select *
from #m_link
--| evaluate the table for records (Start - While Loop)
while exists (
select 1
from #m_link
)
begin
--| 'move' records into the m_out table
insert into #m_out (m_linkID, link_MessageTo, link_MessageType, link_Gateway, link_UserID)
output inserted.m_linkID
into #delete
select top 1 m_linkID
, link_MessageTo
, link_MessageType
, link_Gateway
, link_UserID
from #m_link
--| remove the record from the m_link table
delete
from #m_link
where m_linkID in (
select m_linkID
from #delete
)
end;
select *
from #m_Out
select *
from #m_link
Previous Answer prior to Ops Question Update
you might tag with the version of SQL Server you're using, and explain in more detail the over all scenario and goal.
You could try this:
if not exists (
select 1
from sms.dbo.m_link
where link_check = 0
)
My concern is you are trying to implement a RBAR solution in a set based world. If you are trying to do X based on a row having Y, the approach is wrong.