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From: Robert M. <rob...@gm...> - 2007-03-20 21:40:44
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On 3/20/07, Tyrone Baseck <tyr...@ho...> wrote: > I will get help from the DBA on that query listed earlier. The one listed > below works. Now, what is it doing: > > select * from MGD_REQ_HOLDG m inner join AUTH_REQ_ITEM_HDR a on > m.REQ_ITEM_HDR_ID = a.REQ_ITEM_HDR_ID > where a.auth_req_id > > Do I need to change the MGD_REQ_HOLDG in the first line to look at another > table? You are saying join tables MGD_REQ_HOLDG and AUTH_REQ_ITEM_HDR by matching records where the field REQ_ITEM_HDR_ID in both tables is equal. If you need columns from other tables, then you would add them to your join. The where clause : where a.auth_req_id is incomplete. You should give a value for auth_req_id like : where a.auth_req_id = 42 or not include a where clause at all (which could be quite a large number, depending on the data) > > What is the lower case "m" and "a" for? Table aliases are more convenient than using the entire table name. > > Why do you need to add a "a" to a.REQ_ITEM_HDR_ID instead of doing it > without the "a"? Both tables apparently have a column called REQ_ITEM_HDR_ID, so the database doesn't know which one you are referring to. The table aliases "m" and "a" tell it which one you mean. Rob |
