Insert-Abfrage mit Update

Question

Ich habe die folgenden Tabellen:

Tabelle "Namen":

ID  | Name 
--- | --- 
123 | John 
164 | Peter 
346 | Mark 
679 | Bob 

Tabelle "Unternehmen":

ID  | Company 
--- | --- 
111 | XXX 
666 | YYY 
777 | ZZZ 

Tabelle "Tabelle1":

ID  | c1 | c2 | NameID | CompanyName 
--- | --- | --- | ------ | ----------- 
1254 | 1 |  A |  123  |  XXX 
1548 | 1 |  A |  123  |  YYY 
2649 | 1 |  A |  123  |  ZZZ 
2687 | 3 |  B |  164  |  ZZZ 
2699 | 1 |  A |  164  |  YYY 
2700 | 4 | (NULL) |  346  |  XXX 
2711 | 4 | (NULL) |  346  |  YYY 
2900 | 4 |  A |  679  |  YYY 

Ich muss eine Einfügeabfrage machen, so dass Datensätze mit demselben c1 und c2 (wenn c2 nicht null ist) oder demselben c1 nur (wenn c2 gleich null ist) werden in Table2 eingefügt und die ID in Table2 aktualisiert, um die minimale ID von Table1 zu sein.

sollte das Ergebnis so aussehen:

Tabelle „Tabelle2“:

ID  | c1 | c2 | NameID | CompanyID 
--- | --- | --- | ------ | ----------- 
1254 | 1 |  A |  123  |  111 
1254 | 1 |  A |  123  |  666 
1254 | 1 |  A |  123  |  777 
2687 | 3 |  B |  164  |  777 
2687 | 1 |  A |  164  |  666 
2700 | 4 | (NULL) |  346  |  111 
2700 | 4 | (NULL) |  346  |  666 
2900 | 4 |  A |  679  |  666 

Answer 1

INSERT INTO Table2(ID, c1, c2, NameId, CompanyId) 
SELECT 
    minTable.ID AS ID, 
    t1.c1 AS c1, 
    t1.c2 AS c2, 
    t1.NameId AS NameId, 
    c.ID AS CompanyId 
FROM Table1 t1 
JOIN Companies c ON t1.CompanyName = c.Company 
JOIN (
    SELECT 
     MIN(t1.ID) AS ID, 
     t1.c1 AS c1, 
     t1.c2 AS c2 
    FROM Table1 t1 
    JOIN Companies c ON t1.CompanyName = c.Company 
    GROUP BY c1, c2 
) minTable ON t1.c1 = minTable.c1 AND (t1.c2 = minTable.c2 OR (t1.c2 IS NULL AND minTable.c2 IS NULL))