please help me to create multi insert query

Question

I have got two table

create table t1(cid int, isnews int)

create table t2(nid int,cid int, isnews int)

situations is like this: if t2 contain t2.cid = t1.cid then the t2.isnews = t1.news and if t2 not contain cid of t1 then new record should be inserted in t2 and that t1.cid, t1.isnews should be inserted in t2..

and complete table should be done in single query... i have done the updation part but not able to do insertion part..

update query:

 UPDATE    t22
SET       t22.isnews = t11.isnews 
FROM      t2 AS t22
    JOIN  t1 AS t11
    ON  t11.cid= t22.cid

i have prepared below cursor for insert... is it good? :

DECLARE @clntid INT
DECLARE @clntnewsltr INT
DECLARE clientnews CURSOR FOR 
SELECT clientid,newsLetter 
FROM clients 
WHERE clientid NOT IN (SELECT clientid FROM clientprivacy) 

OPEN clientnews  
FETCH NEXT FROM clientnews INTO @clntid,@clntnewsltr  

WHILE @@FETCH_STATUS = 0  
BEGIN  

   INSERT INTO clientprivacy (clientId,tdNewsLetters) VALUES(@clntid, @clntnewsltr)
 FETCH NEXT FROM clientnews INTO @clntid,@clntnewsltr  
END  

CLOSE clientnews  
DEALLOCATE clientnews

Answer 1

I think this is the kind of thing you're after:

--INSERT t2 (cid, isnews)
SELECT t1.cid, t1.isnews
FROM t1
    LEFT JOIN t2 ON t1.cid = t2.cid
WHERE t2.cid IS NULL

I've commented out the INSERT line - I recommend you run the SELECT on it's own first to check it does give you the correct result (all records from t1 that don't have a matching cid in t2).

I've assumed t2.nid is an IDENTITY column.

Answer 2

You will be so much better off without cursors :) Cursors take MUCH longer to run in large data sets.

It is true you can use a LEFT JOIN, but you can also use a SELECT in your WHERE clause. Most of the time it's a style choice.

CREATE TABLE table1(col_1 int, col_2 int)
CREATE TABLE table2(nid int, col_1 int, col_2 int)


INSERT INTO table2 (col_1,col_2) 
SELECT col_1,col_2 
FROM table1 
WHERE col_1 NOT IN (SELECT col_1 FROM table2)