如何将插入查询和更新查询与不同的表合并到单个查询中？

Question

How to combine this query into single query?

INSERT INTO transactions (quantity) VALUES (2);
UPDATE items SET stock = 5 WHERE id = 1;

thank you.

Answer 1

Simple answer? You can't. There is no SQL command that allows you to insert into one table and simultaneously update another table.

You can, however, make them part of the same transaction so that they both happen, or both don't happen, so you don't end up in a situation where the INSERT succeeded but the UPDATE failed

Answer 2

You can update two tables at the same time but updating one and inserting other table in one query is not possible. But the loop hole would the use of procedures with start transaction like @Caius Jard mentioned.

Answer 3

In Postgres, you can use an updatable CTE:

with i as (
    INSERT INTO transactions (quantity)
        VALUES (2)
        RETURNING *
    )
UPDATE items
SET stock = 5
WHERE id = 1;

The returning clause would actually let you use values from the insert in the update . This construct is a big convenience in Postgres.