[英]INSERT rows into multiple tables in a single query, selecting from an involved table
I have two tables of the following form (ie, every foo is linked to exactly one bar). 我有两个以下表格的表格(即每个foo都链接到一个条形图)。
CREATE TABLE foo (
id INTEGER PRIMARY KEY,
x INTEGER NOT NULL,
y INTEGER NOT NULL,
...,
bar_id INTEGER UNIQUE NOT NULL,
FOREIGN key (bar_id) REFERENCES bar(id)
);
CREATE TABLE bar (
id INTEGER PRIMARY KEY,
z INTEGER NOT NULL,
...
);
It's easy to copy rows in foo
which meet a particular condition using a nested query: 使用嵌套查询复制满足特定条件的foo
中的行很容易:
INSERT INTO foo (...) (SELECT ... FROM foo WHERE ...)
But I can't figure out how to make a copy of the associated row in bar
for each row in foo
and insert the id of bar
into the new foo
row. 但我无法弄清楚如何使相关行的拷贝在bar
中的每一行foo
和插入的ID bar
到新foo
行。 Is there any way of doing this in a single query? 有没有办法在单个查询中执行此操作?
Concrete example of desired result: 期望结果的具体例子:
-- Before query:
foo(id=1,x=3,y=4,bar_id=100) ..... bar(id=100,z=7)
foo(id=2,x=9,y=6,bar_id=101) ..... bar(id=101,z=16)
foo(id=3,x=18,y=0,bar_id=102) ..... bar(id=102,z=21)
-- Query copies all pairs of foo/bar rows for which x>3:
-- Originals
foo(id=1,x=3,y=4,bar_id=101) ..... bar(id=101,z=7)
foo(id=2,x=9,y=6,bar_id=102) ..... bar(id=102,z=16)
foo(id=3,x=18,y=0,bar_id=103) ..... bar(id=103,z=21)
-- "Copies" of foo(id=2,...) and foo(id=3,...), with matching copies of
-- bar(id=102,...) and bar(id=103,...)
foo(id=4,x=9,y=6,bar_id=104) ..... bar(id=104,z=16)
foo(id=5,x=18,y=0,bar_id=105) ..... bar(id=105,z=21)
... after some more info from OP. ...来自OP的更多信息之后。 Consider this demo: 考虑这个演示:
-- DROP TABLE foo; DROP TABLE bar;
CREATE TEMP TABLE bar (
id serial PRIMARY KEY -- using a serial column!
,z integer NOT NULL
);
CREATE TEMP TABLE foo (
id serial PRIMARY KEY -- using a serial column!
,x integer NOT NULL
,y integer NOT NULL
,bar_id integer UNIQUE NOT NULL REFERENCES bar(id)
);
Insert values - bar
first. 插入值 - 先bar
。
It would be very helpful if you provided test data in your question like this! 如果你在这样的问题中提供测试数据会非常有用 !
INSERT INTO bar (id,z) VALUES
(100, 7)
,(101,16)
,(102,21);
INSERT INTO foo (id, x, y, bar_id) VALUES
(1, 3,4,100)
,(2, 9,6,101)
,(3,18,0,102);
Set sequences to current values or we get duplicate key violations: 将序列设置为当前值或我们得到重复的密钥违规:
SELECT setval('foo_id_seq', 3);
SELECT setval('bar_id_seq', 102);
Checks: 检查:
-- SELECT nextval('foo_id_seq')
-- SELECT nextval('bar_id_seq')
-- SELECT * from bar;
-- SELECT * from foo;
Query: 查询:
WITH a AS (
SELECT f.x, f.y, bar_id, b.z
FROM foo f
JOIN bar b ON b.id = f.bar_id
WHERE x > 3
),b AS (
INSERT INTO bar (z)
SELECT z
FROM a
RETURNING z, id AS bar_id
)
INSERT INTO foo (x, y, bar_id)
SELECT a.x, a.y, b.bar_id
FROM a
JOIN b USING (z);
This should do what your last update describes. 这应该是您上次更新描述的内容。
The query assumes that z
is UNIQUE
. 该查询假定z
是UNIQUE
。 If z
is not unique, it gets more complex. 如果z
不是唯一的,它会变得更复杂。 Refer to Query 2 in this related answer for a ready solution using the window function row_number()
in this case. 在这种情况下,请参考此相关答案中的查询2,以获得使用窗口函数row_number()
的现成解决方案。
Also, consider replacing the 1:1 relation between foo
and bar
with a single united table. 另外,考虑用单个联合表替换foo
和bar
之间的1:1关系 。
Second answer after more info. 更多信息后的第二个答案。
If you want to add rows to foo
and bar
in a single query, you can use a data modifying CTE since PostgreSQL 9.1 : 如果要在单个查询中向foo
和 bar
添加行,则可以使用自PostgreSQL 9.1以来修改CTE的数据 :
WITH x AS (
INSERT INTO bar (col1, col2)
SELECT f.col1, f.col2
FROM foo f
WHERE f.id BETWEEN 12 AND 23 -- some filter
RETURNING col1, col2, bar_id -- assuming bar_id is a serial column
)
INSERT INTO foo (col1, col2, bar_id)
SELECT col1, col2, bar_id
FROM x;
I draw values from foo
, insert them in bar
, have them returned together with an auto-generated bar_id
and insert that into foo
. 我从foo
绘制值,将它们插入bar
,让它们与自动生成的bar_id
一起返回并将其插入foo
。 You can use any other data, too. 您也可以使用任何其他数据。
Here is a working demo to play with on sqlfiddle . 这是一个在sqlfiddle上玩的工作演示 。
Original answer with basic information before clarifications. 在澄清之前提供基本信息的原始答案。
The basic form is: 基本形式是:
INSERT INTO foo (...)
SELECT ... FROM foo WHERE ...
No parenthesis needed. 不需要括号。 You can do the same with any table 你可以对任何表做同样的事情
INSERT INTO foo (...)
SELECT ... FROM bar WHERE ...
And you can join to the table you insert into in the SELECT: 您可以加入到SELECT中插入的表:
INSERT INTO foo (...)
SELECT f.col1, f.col2, .. , b.bar_id
FROM foo f
JOIN bar b USING (foo_id); -- present in foo and bar
It's just a SELECT like any other - that can include the table you are inserting into. 它只是一个SELECT,就像其他任何一样 - 可以包括你插入的表。 The rows are first read, and then inserted. 首先读取行,然后插入。
if id
of bar
is serial and have default value nextval('bar_id_seq'::regclass)
you can manually call this function to get new ids in cte 如果bar
id
是serial并且具有默认值nextval('bar_id_seq'::regclass)
您可以手动调用此函数以获取nextval('bar_id_seq'::regclass)
新ID
with
s_bar as (
SELECT id, z, nextval('bar_id_seq'::regclass) new_id
FROM bar
WHERE ...
),
s_foo as (
SELECT x, y, bar_id
FROM foo
WHERE ...
),
i_bar as (
INSERT INTO bar (id, z)
SELECT new_id, z
FROM s_bar
),
i_foo as (
INSERT INTO foo (x, y, bar_id)
SELECT f.x, f.y, b.new_id
FROM s_foo f
JOIN s_bar b on b.id = f.bar_id
)
SELECT 1
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