Sql – Oracle: how to UPSERT (update or insert into a table?)

mergeoraclesqlupsert

The UPSERT operation either updates or inserts a row in a table, depending if the table already has a row that matches the data:

if table t has a row exists that has key X:
    update t set mystuff... where mykey=X
else
    insert into t mystuff...

Since Oracle doesn't have a specific UPSERT statement, what's the best way to do this?

Best Answer

The MERGE statement merges data between two tables. Using DUAL allows us to use this command. Note that this is not protected against concurrent access.

create or replace
procedure ups(xa number)
as
begin
    merge into mergetest m using dual on (a = xa)
         when not matched then insert (a,b) values (xa,1)
             when matched then update set b = b+1;
end ups;
/
drop table mergetest;
create table mergetest(a number, b number);
call ups(10);
call ups(10);
call ups(20);
select * from mergetest;

A                      B
---------------------- ----------------------
10                     2
20                     1

Related Solutions

Sql – Insert into … values ( SELECT … FROM … )

Try:

INSERT INTO table1 ( column1 )
SELECT  col1
FROM    table2

This is standard ANSI SQL and should work on any DBMS

It definitely works for:

Oracle
MS SQL Server
MySQL
Postgres
SQLite v3
Teradata
DB2
Sybase
Vertica
HSQLDB
H2
AWS RedShift
SAP HANA
Google Spanner

Sql – Solutions for INSERT OR UPDATE on SQL Server

don't forget about transactions. Performance is good, but simple (IF EXISTS..) approach is very dangerous.
When multiple threads will try to perform Insert-or-update you can easily get primary key violation.

Solutions provided by @Beau Crawford & @Esteban show general idea but error-prone.

To avoid deadlocks and PK violations you can use something like this:

begin tran
if exists (select * from table with (updlock,serializable) where key = @key)
begin
   update table set ...
   where key = @key
end
else
begin
   insert into table (key, ...)
   values (@key, ...)
end
commit tran

begin tran
   update table with (serializable) set ...
   where key = @key

   if @@rowcount = 0
   begin
      insert into table (key, ...) values (@key,..)
   end
commit tran

Best Answer

Related Solutions

Sql – Insert into … values ( SELECT … FROM … )

Sql – Solutions for INSERT OR UPDATE on SQL Server

Related Topic