Execute query according to the result of another - mysql

Question

I have a query that gives output "OK".
I want to use that result from the query to run another query.
If result is OK then don't run.
If it is ERROR, then run.
The queries are slow and I don't want to execute the second query if the result is OK. The second query checks what is wrong.
How I can do this? I checked in the Internet but I don't know if there is such function and it's name. I don't want to use nested queries or WITH expressions
Thanks!

Answer 1

Use Try and Catch to error handling and do what you want to execute as per below:
If Query 1 is executed then query 2 skip otherwise execute query 2 if any error in query 1:
Begin Try
--Query 1
End Try
Begin Catch
-- Query 2
End catch

Answer 2

you can put result of the query into variable and then check it using IF...ELSE
declare #test varchar(10) = 'ok';
if #test != 'ok'
begin
--query if not 'ok'
end
else
begin
--query if 'ok', or you can remove `else` at all if not required
end
DEMO

Answer 3

Well, you can create a variable in which you store the result of a function that returns 'OK' or 'KO' (How to create a function with SQL Server).
Then you can use an IF statement where you execute different queries
IF statement SQL Server.
This could be an idea.

Answer 4

Capture result set into a variable. Also ensure your condition returns one or other and only one column
I have added a sample query
declare #output VARCHAR(10)
SET #OUTPUT =
--sample query
(select case when SUM(s.SellingValue) = SUM(h.SellingValue) then 'OK' ELSE 'ERROR' END OUTPUT
from Missing_Sales s inner join Missing_Sales_TH h on s.Branch_no = h.Branch_no and s.date = h.Date)
BEGIN
IF #output = 'OK'
--sample query
SELECT * FROM Missing_Sales
ELSE
--sample query
SELECT * FROM Missing_Sales_TH
END