How to write the condition

Question

Hi guys, I wonder how to do this in Disco Desktop( not in admin). How to write the exists like a statement in “where close”
select * from emp
where exists (select 'x' from emp_1
where emp_1.sal>2999
and empno=emp.empno)
Thank in advance.

Answer 1

Hi
In order to use a subquery in a condition there has to be an existing worksheet already in the workbook. If you don't have an existing worksheet then you will still see the Create Subquery option but you won't be able to use it.
Here's a workflow to try it out using SYSDATE:
1. First of all, make sure you open Desktop, not Plus.
2. Create a new Table worksheet containing only a calculation, SYSDATE - you do this by continually clicking Next until you get to step 6 of the wizard, ignoring the message which says you have no items in the worksheet
3. In step 6, click the New button
4. Leave the calculation name as Calculation0 and add SYSDATE into the calculation
5. Click the OK button
6. Click the Finish button - you now have the current date in your worksheet
7. From the menu bar, select Sheet | New Sheet and select Table
8. Once again continually click Next until you get to step 6 of the wizard, ignoring the message which says you have no items in the worksheet
9. In step 6, click the New button
10. Leave the calculation name as Calculation1 and once again add SYSDATE into the calculation
11. Click the OK button
12. Click the Finish button - you now have the current date in your second worksheet
13. Staying in the second worksheet, from the menu bar select Tools | Conditions
14. Click the New button to create a new condition
15. In Item use the drop-down and select Calculation1
16. Under the drop-down for Value(s) you should see Create Subquery
17. Notice how Discoverer has automatically selected Calculation0? This is the only item so naturally it will be selected. However, if you have more than one item Discoverer picks an item of the same data type
18. Nothing more to do now except click the OK button a couple of times
What you have done is said that the SYSDATE in worksheet2 is dependent upon the formula in sheet1 which happens to be also SYSDATE.
To prove this working, go back into sheet1 and change the formula to SYSDATE -1, then go back to sheet 2 and refresh it. This time you should get no data returned showing that the subquery is working.
By the way, any worksheets you create in Desktop that use subqueries will still work in Plus even though you cannot edit the subquery itself in Plus.
Best wishes
Michael