Syntax strictly depends on which SQL DBMS you're using. Here are some ways to do it in ANSI/ISO (aka should work on any SQL DBMS), MySQL, SQL Server, and Oracle. Be advised that my suggested ANSI/ISO method will typically be much slower than the other two methods, but if you're using a SQL DBMS other than MySQL, SQL Server, or Oracle, then it may be the only way to go (e.g. if your SQL DBMS doesn't support MERGE
):
ANSI/ISO:
update ud
set assid = (
select sale.assid
from sale
where sale.udid = ud.id
)
where exists (
select *
from sale
where sale.udid = ud.id
);
MySQL:
update ud u
inner join sale s on
u.id = s.udid
set u.assid = s.assid
SQL Server:
update u
set u.assid = s.assid
from ud u
inner join sale s on
u.id = s.udid
PostgreSQL:
update ud
set assid = s.assid
from sale s
where ud.id = s.udid;
Note that the target table must not be repeated in the FROM
clause for Postgres.
Oracle:
update
(select
u.assid as new_assid,
s.assid as old_assid
from ud u
inner join sale s on
u.id = s.udid) up
set up.new_assid = up.old_assid
SQLite:
update ud
set assid = (
select sale.assid
from sale
where sale.udid = ud.id
)
where RowID in (
select RowID
from ud
where sale.udid = ud.id
);
Best Answer
In your
Join
condition am sure one column is ofInteger
type and other one isVarchar
type.since
Int
has higher precedence thanvarchar
,Varchar
column will be implicitly converted toInt
So explicitly convert the
Int
column to varchar.I have considered
Header.docId
asInt
type if no, then convertHistory.Id
tovarchar