If it is incorrect, then you can get wrong results.
Results after the update: a b c d ———————————— 1 x y z 2 a1 b1 c1 3 t x z DB2 LUW: –Same as Oracle– UPDATE TABLEA SET (b, c, d) = (SELECT b1, c1, d1 from TABLEB WHERE TABLEB.a1 = TABLEA.a and TABLEB.e1 40); Results after the update: a b c d ———————————— 1 x y z 2 a1 b1 c1 3 t x z NOTE: It is very important to make sure that your where clause for the update statement is correct since that is what identifies the records that the update statement is going to qualify and do the update upon.The chapter contains these topics: An object type is like a tree structure, where the branches represent the attributes.Attributes that are objects sprout subbranches with their own attributes.In that post, we had covered how you can update the data in a table with the data from another table. Since it resides in a database on a separate instance, we can first create a linked server to it first and then either reference it using a couple of ways as was shown in that blog post on linked server. Doing an insert into a table with data from other tables (within the same schema or separate schemas or separate databases or separate databases on separate instances) is also fairly simple. Let’s consider this hypothetical scenario to illustrate this (using SQL Server lingo though the same approach is available in Oracle and DB2 as well) – Say the summary table “tbl Emp Summary” that this reader wanted to insert the data into resides in a database called EXECUTIVE in a schema called ANALYSIS. Or we can simply create a synonym for it and use it. – all the normal T-SQL operations you would be able to do including inserting it into the summary table.