Oracle SQL — Merge into example

Merge is a good technique to updating values quickly . If you want to update values in a big table from a table(with only columns meant for update) , you may write the code like below….

PS -> If you have indexes created on the columns of match , the merge update will be faster.

Now the code is ….

Merge /*+ PARALLEL */ into <schema>.<table> t1 using

(select col1 , col2 from <schema>.<table> ) t2 on t1.<join column > = t2.<join column>

when matched then update set t1.column1 = t2.column1

where t1.xxx = ‘Y’ //optional

Ofcoure the above one is a variant of MERGE , there are many ways …but this is one of the way…