如何仅将唯一记录从另一个表导入到一个表中？

Question

I am trying to update a table in SQL Server. Table is called table1 with columns(code, desc). I want to update table1 with unique records from table2(code, desc). table2 is a copy of table1 but it contains records that are not present in table1.

Answer 1

Sounds like you want an INSERT

Something like this should work:

INSERT INTO table1 (code, desc)
SELECT t2.code, t2.desc
FROM table2 t2
LEFT JOIN table1 t1 on t2.code = t1.code and t1.desc = t2.desc
WHERE t1.code is null --Ignore records that already exist in table1

... Adjust join clause accordingly.

Answer 2

To update table1.desc with values from matching rows in table2 simply do:

update t1 set 
  t1.desc = t2.desc
from table1 t1
join table2 t2 on t2.code = t1.code;