A bit redundant, but how about:
CREATE TABLE table_a (akey integer, avalue float);
CREATE TABLE table_b (bkey integer, bvalue float);
INSERT INTO table_a (akey, avalue) VALUES (1, 1.0);
INSERT INTO table_a (akey, avalue) VALUES (2, 2.0);
INSERT INTO table_a (akey, avalue) VALUES (3, 3.0);
INSERT INTO table_b (bkey, bvalue) VALUES (1, 101.0);
INSERT INTO table_b (bkey, bvalue) VALUES (2, 102.0);
INSERT INTO table_b (bkey, bvalue) VALUES (4, 104.0);
UPDATE table_a SET avalue=(SELECT bvalue FROM table_b WHERE akey=bkey)
WHERE EXISTS(SELECT 1 FROM table_b WHERE akey=bkey);
I think there is no multi-table update idiom in SQLite because there
isn't one in SQL.
--David
Robert Poor writes:
> I'd like to be able to update specific records in table A from joined
> records in table B. So for example:
>
> CREATE TABLE "table_a" ("key" integer, "value" float);
> CREATE TABLE "table_b" ("key" integer, "value" float);
> INSERT INTO "table_a" ("key", "value") VALUES (1, 1.0), (2, 2.0),(3,
> 3.0);
> INSERT INTO "table_b" ("key", "value") VALUES (1, 101.0), (2, 102.0),(4,
> 104.0);
>
> In an imaginary version of SQLite ;) this might be written as:
>
> # UPDATE table_a
> # JOIN table_b
> # SET table_a.value = table_b.value
> # WHERE table_a.key1 = table_b.key
>
> resulting in table_a:
>
> key | value
> 1 | 101
> 2 | 102
> 3 | 3
>
> ... that is to say, update table_a.value from table_b.value, but only
> on rows where table_a.key = table_b.key
>
> I've pored over the UPDATE syntax, but I don't see a way to do this.
> What's the idiom in SQLite?
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