How to loop cy.task according to the result - random

Question

I'm testing the CRUDs for a page in my application, where a registry requires an unique ID as a 5 digit number to be successfully created.
I would like to get a random available ID of that table to use in the tests, that can be achieved with the following sql query:
cy.task(
'sqlQuery',
`select count(*) as "count" from clients where client_id = '${
Math.floor(Math.random() * 90000) + 10000
}'`
)
The point is that the random number perhaps is not available to be used as the ID, so i would need to loop this same task until the generated number is available:
cy.task(
'sqlQuery',
`select count(*) as "count" from clients where client_id = '${
Math.floor(Math.random() * 90000) + 10000
}'`
).then((result: any) => {
if (result.rows[0].count === 0) {
// My code to submit the form with the generated number
// break the loop
} else {
// Repeat all of this (where i'm asking for help)
}
})
If count returns 0 it means it's there's no registry using it, otherwise it's not available.
I guess the final solution could be using some while loop, but I found this way would be more clear to you all know what i'm needing.
I tried some approachs like this, but just discovery that its impossible to assign a new value to a variable inside the .then block, so it seems like i did an endless loop.
let available = false
do {
cy.task(
'sqlQuery',
`select count(*) as "count" from clients client_id = '${
Math.floor(Math.random() * 90000) + 10000
}'`
).then((result: any) => {
if (result.rows[0].count === 0) {
// Code to submit the form with the generated number
available = true
}
})
} while (available === false)

Answer 1

Ask SQL what ids are present and check the random one against those?
Something like this:
cy.task('sqlQuery', 'select client_id from clients')
.then((result: any) => {
const ids: string[] = result.rows;
function getNewId(trys = 0) {
if (trys > 1000) throw new Error('failed')
const newId = Math.floor(Math.random() * 90000) + 10000
if (ids.includes(newId)) {
return getNewId(++trys)
}
return newId
}
const newId = getNewId()
cy.wrap(newId).as('newId')
})
Update
Changed to a recursive javascript function, as I found when testing .should() it does not re-evaluate Math.floor(Math.random() * 90000) + 10000
It's been a while since I did some SQL, but maybe this correlated subquery is more efficient
SELECT last + 1 as newId FROM (
SELECT MAX(id) as last FROM clients
)

Answer 2

You can use a query like this to get 3 unused IDs for your tests
MySQL:
SELECT a.id+1 as 'ids'
FROM clients a
WHERE
NOT EXISTS (SELECT * FROM clients b WHERE a.id+1 = b.id) AND
a.id+1 < 100000
ORDER BY a.id
LIMIT 3
Oracle 11:
SELECT a.id+1 as ids
FROM clients a
WHERE
NOT EXISTS (SELECT * FROM clients b WHERE a.id+1 = b.id) AND
a.id+1 < 10000 AND
rownum <= 3
ORDER BY a.id;
Oracle 12:
SELECT a.id+1 as ids
FROM clients a
WHERE
NOT EXISTS (SELECT * FROM clients b WHERE a.id+1 = b.id) AND
a.id+1 < 10000
ORDER BY a.id
FETCH FIRST 3 ROWS ONLY;
This will search for unused IDs checking always the next ID, limiting it to 3 rows (you can limit the amount you need) to improve performance. And only available IDs, under 100000 (has only 5 digits)
For example:
Your table has de IDs (1, 3, 5, 6, 7, 9, 10)
This query will check if the IDs (2, 4, 6, 8, 10, 11) exist in the table. If it doesnt exists, it will return. So this example will return (2, 4, 8)