Question

I have two tables. One is simple string/ID look up:

StrTable:

 str_key String 0       'a' 1       'b' 

where the strings are unique. The other is more complex, and includes the shared string_id

ValTable:

 str_key other_key val 0        0        1.234 0        1        1.567 1        0        1.890 

Now, I want to do an update on ValTable, using a string which I lookup to get the str_key via StrTable. The simple update would be:

UPDATE ValTable SET val = 2.124 WHERE str_key = 0 AND other_key = 1 LIMIT 1 IF @@ROWCOUNT=0 INSERT INTO ValTable VALUES (0,1,2.124); 

So how can I modify this to include looking up the str_key with some string ‘a’? I assume I need a join, but I’ve never done a join in an update. Or can I just add more to my where clause?

Answer 1

This is the syntax you need:

UPDATE  v SET     val = 2.124 FROM    ValTable v         INNER JOIN                 StringTable s                 ON v.str_key = s.str_key WHERE   s.String = 'a' AND     v.other_key = 1  IF @@ROWCOUNT = 0 BEGIN          INSERT         INTO    ValTable         SELECT  str_key, 1, 2.124         FROM    StringTable         WHERE   String = 'a'  END