Passing Values from table to CTE - common-table-expression

Question

I have a table of slot numbers, i.e. warehouse slot numbers.
0110H
0310H
0311H
0312H
0313H
0314H
The table is called WarehouseLocationLimits and the column name is “F1.” The 3rd and 4th digits of the of the above slot numbers represent a maximum number of bays in an aisle of the warehouse.
I have the following code
DECLARE #I INT
SET #I = 1;
WITH CTS(BAY) AS (
SELECT #I
UNION ALL
SELECT BAY + 1 FROM CTS
WHERE BAY < 5
)
SELECT F1, LEFT(F1, 2) AISLE, CAST(SUBSTRING(F1, 3, 2) AS INTEGER) BAYMAX, SUBSTRING(F1, 5, 1) LEVEL, BAY
FROM WarehouseLocationLimits WL, CTS
Where F1 IS NOT NULL
order by F1, BAY
Which generates something like the following:
0110H 01 10 H 1
0110H 01 10 H 2
0110H 01 10 H 3
0110H 01 10 H 4
0110H 01 10 H 5
0310H 03 10 H 1
0310H 03 10 H 2
0310H 03 10 H 3
0310H 03 10 H 4
0310H 03 10 H 5
Note: for each “slot” the CTE is generating 5 lines because of the literal ‘5’ in the WHERE clause of the CTE. I need to pass the value CAST(SUBSTRING(F1, 3, 2) AS INTEGER) of each slot to the CTE. How can I do that?
Thanks in advance for your help
Clyde

Answer 1

Ok. I got it. The solution is the following:
WITH CTS(SLOTNO, AISLE, BAY, LEVEL)
AS (
SELECT F1, LEFT(F1, 2), SUBSTRING(F1, 3, 2), ASCII(SUBSTRING(F1, 5, 1))
FROM WarehouseLocationLimits WL1
WHERE F1 IS NOT NULL
UNION ALL
SELECT WL2.F1, LEFT(WL2.F1, 2), BAY, LEVEL - 1
FROM WarehouseLocationLimits WL2, CTS
WHERE WL2.F1 = CTS.SLOTNO AND LEVEL > ASCII('A')
)
SELECT *, CHAR(LEVEL)
FROM CTS
order by SLOTNO, LEVEL DESC
I didn't understand that the first query (i.e., that one atop the "UNION ALL" is a "seed" query and runs only once for each row of the table. Having understood that, it all fell into place for me.