问题
Attempt to generalize my questions... I want to execute a stored procedure for each result returned by a SELECT statement.
Mentally I want to try something like EXEC myStoredProc (SELECT id FROM sometable WHERE cond = @param)
More details related to my specific case... I have a SaaS application. I would like to delete a tenant from the system. Before I can delete the tenant I must delete all records in the database associated with that tenant.
Tenants own items such as Forms which contain many different types of Fields. I already have a stored proc that deletes a Form and all of its associated items (like Fields). For maintenance reasons (Ie. not wanted to duplicate the logic that determines dependances and associations between records and a form) I'd like to just call that StoredProc for each Form that belongs to a Tenant.
I can retrieve the list of forms by running a query like... Select formId FROM Forms WHERE Tenant = @TenantId
What I want to do with the result of that query is EXEC my Delete_Form stored procedure.
How can I do this?
回答1:
In the case where you don't have control of the foreign keys and can't do cascade deletes, you could create a cursor to loop thru and execute the stored proc for each.
declare @formID int
declare FormsCursor cursor fast_forward for Select formId FROM Forms WHERE Tenant = @Tenant
open FormsCursor
fetch next from FormsCursor into @formID
while @@fetch_status = 0
begin
exec Delete_Form @formID
fetch next from FormsCursor into @formID
end
close FormsCursor
deallocate FormsCursor
回答2:
You could just turn Cascade delete on and deleting the parent record would delete all child records associated with it.
If not you'll have to create a cursor (The link is for sql server, but I would assume that cursors for other RDBMS are similar) and loop through each of the results pulling out the form id and executing the [Delete_Field_Procedure] for each one.
来源：https://stackoverflow.com/questions/859759/sql-iterating-over-a-list-to-call-exec-on-each-item