Question

I have a trigger that check data before insert to another table

  IF NOT EXISTS (SELECT *
                 FROM   inserted,
                        Clients
                 WHERE  Inserted.Account = Clients.Account)
  BEGIN
      INSERT INTO Clients(GUID, Account, ....)
      SELECT GUID, Account
      FROM   inserted
  END 

it’s working fine if one row updated
but if use batch update its not working.

for example Update Table1 set Number = Number where account <> ''
If the second table (Clients) is not empty, nothing added
if it’s empty its work well

Answer 1

Rather than doing a check then insert, why not write it as a single INSERT statement:

Insert into Clients (GUID , Account .....)
Select i.GUID , i.Account 
from
   inserted i
      left join
   Clients c
      on
          i.Account = c.Account
where
    c.Account is null

The NULL check in the WHERE clause can be for any column in Clients which isn’t nullable.

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Even if you keep the EXISTS check in, you still need something like the above, because the EXISTS check is asserting something about all of the rows in inserted – when it may consist of some rows for which the assertion is true, and some rows for which it is false.