更新时间:2023-02-26 07:56:18
如果幸运的是,您可以运行当前的 PostgreSQL 9.1 ,则可以通过单个命令找到一种简洁,快速的解决方案使用新的 修改数据的CTE .
If you are lucky enough to run the current PostgreSQL 9.1, there is an elegant and fast solution with a single command using the new data-modifying CTEs.
No such luck with MySQL which does not support Common Table Expressions (CTE), not to mention data-modifying CTE.
假设(col1, col2)
最初是唯一的:
t.id
的序列号.t.id
will be wasted.
WITH s AS (
SELECT id, col1, col2
FROM t
-- WHERE some condition
)
,i AS (
INSERT INTO t (col1, col2)
SELECT col1, col2 -- I gather from comments that id is a serial column
FROM s
RETURNING id, col1, col2
)
INSERT INTO tu (t, u)
SELECT i.id, tu.u
FROM tu
JOIN s ON tu.t = s.id
JOIN i USING (col1, col2);
如果(col1, col2)
不是唯一,我会看到另外两种方式:
If (col1, col2)
is not unique, I see two other ways:
row_number()
非唯一行唯一.INSERT
行在t.id
空间中没有孔.row_number()
to make non-unique rows unique.INSERT
rows without holes in the t.id
space just like in the query above.
WITH s AS (
SELECT id, col1, col2
, row_number() OVER (PARTITION BY col1, col2) AS rn
FROM t
-- WHERE some condition
)
,i AS (
INSERT INTO t (col1, col2)
SELECT col1, col2
FROM s
RETURNING id, col1, col2
)
,r AS (
SELECT *
, row_number() OVER (PARTITION BY col1, col2) AS rn
FROM i
)
INSERT INTO tu (t, u)
SELECT r.id, tu.u
FROM r
JOIN s USING (col1, col2, rn) -- match exactly one id per row
JOIN tu ON tu.t = s.id;
t.id
的数字空间中有孔,则会相应地为新行刻录序列号.t
中的新插入物会重复出现键错误,这些错误会从序列中提取id
的默认值.我将此作为命令的最后一步进行了集成.最快的这样最安全.
t.id
, sequence numbers will be burnt for the new rows accordingly.t
that draw the default for id
from the sequence. I integrated this as final step into the command. Fastest & safest this way.
WITH s AS (
SELECT max(id) AS max_id
FROM t
)
,i AS (
INSERT INTO t (id, col1, col2)
SELECT id + s.max_id, col1, col2
FROM t, s
)
,j AS (
INSERT INTO tu (t, u)
SELECT tu.t + s.max_id, tu.u
FROM tu, s
)
SELECT setval('t_id_seq', s.max_id + s.max_id)
FROM s;
手册中有关 setval()的详细信息.
Details about setval() in the manual.
进行快速测试.
CREATE TEMP TABLE t (id serial primary key, col1 text, col2 text);
INSERT INTO t (col1, col2) VALUES
('A', 'B')
,('C', 'D');
CREATE TEMP TABLE tu (t int, u int);
INSERT INTO tu VALUES
(1, 100)
,(1, 101)
,(2, 100)
,(2, 102);
SELECT * FROM t;
SELECT * FROM tu;
最近有一个类似的问题,我在其中提供了一个类似的答案.以及版本 8.3 的替代版本,其中没有CTE和窗口功能.
There was a somewhat similar question recently, where I provided a somewhat similar answer. Plus alternatives for version 8.3 without CTEs and window functions.