How the Query works

Hi! The SQL query you provided is utilizing a CASE statement along with the EXISTS function to determine the value of the variable @BillOfSupply based on a condition. Here's a breakdown of how it works:

1. The query starts with SELECT @BillOfSupply = Case, which means it is setting the variable @BillOfSupply based on the result of the CASE statement.

2. Inside the CASE statement, it checks if there is at least one row returned by the subquery:

SELECT 1 FROM INV1 WHERE "DocEntry" = @list_of_cols_val_tab_del

The EXISTS function returns true if the subquery returns any rows, and false if it does not.

3. If the condition is met (i.e., rows are found where "DocEntry" matches @list_of_cols_val_tab_del in the INV1 table), THEN the value '1' is assigned to @BillOfSupply. If the condition is not met, @BillOfSupply will be NULL because there is no ELSE specified in the CASE statement.

In simple terms, this query is checking if a specific condition is met in the INV1 table based on the value of @list_of_cols_val_tab_del, and then setting @BillOfSupply to '1' if the condition is true.

If you have any specific examples or cases where you'd like to see how this query would behave, feel free to provide additional details for a more targeted explanation. Let me know if you need further clarification!