I want to insert data into 3 tables with a single query.
My tables looks like below:
CREATE TABLE sample (
id bigserial PRIMARY KEY,
lastname varchar(20),
firstname varchar(20)
);
CREATE TABLE sample1(
user_id bigserial PRIMARY KEY,
sample_id bigint REFERENCES sample,
adddetails varchar(20)
);
CREATE TABLE sample2(
id bigserial PRIMARY KEY,
user_id bigint REFERENCES sample1,
value varchar(10)
);
I will get a key in return for every insertion and I need to insert that key in the next table.
My query is:
insert into sample(firstname,lastname) values('fai55','shaggk') RETURNING id;
insert into sample1(sample_id, adddetails) values($id,'ss') RETURNING user_id;
insert into sample2(user_id, value) values($id,'ss') RETURNING id;
But if I run single queries they just return values to me and I cannot reuse them in the next query immediately.
How to achieve this?
Use data-modifying CTEs:
WITH ins1 AS (
INSERT INTO sample(firstname, lastname)
VALUES ('fai55', 'shaggk')
-- ON CONFLICT DO NOTHING -- optional addition in Postgres 9.5+
RETURNING id AS user_id
)
, ins2 AS (
INSERT INTO sample1 (user_id, adddetails)
SELECT user_id, 'ss' FROM ins1
-- RETURNING user_id -- only if used in turn
)
INSERT INTO sample2 (user_id, value) -- same here
SELECT user_id, 'ss' FROM ins1;
Each INSERT
depends on the one before. SELECT
instead of VALUES
makes sure nothing is inserted in subsidiary tables if no row is returned from a previous INSERT
. (Related: the ON CONFLICT
clause in Postgres 9.5+)
It's also a bit shorter and faster this way.
Typically, it's more convenient to provide complete data rows in one place:
WITH data(firstname, lastname, adddetails, value) AS (
VALUES -- provide data here
(text 'fai55', text 'shaggk', text 'ss', text 'ss2') -- see below
-- more? -- works for multiple input rows
)
, ins1 AS (
INSERT INTO sample (firstname, lastname)
SELECT firstname, lastname FROM data -- DISTINCT? see below
ON CONFLICT DO NOTHING -- required UNIQUE constraint
RETURNING firstname, lastname, id AS sample_id
)
, ins2 AS (
INSERT INTO sample1 (sample_id, adddetails)
SELECT sample_id, adddetails
FROM data
JOIN ins1 USING (firstname, lastname)
RETURNING sample_id, user_id
)
INSERT INTO sample2 (user_id, value)
SELECT user_id, value
FROM data
JOIN ins1 USING (firstname, lastname)
JOIN ins2 USING (sample_id);
You may need explicit type casts in a separate VALUES
expression (as opposed to a VALUES
expression attached to an INSERT, where data types are derived from the target table.
If multiple rows can come with identical (firstname, lastname)
, you may need to fold duplicates for the first insert:
...
INSERT INTO sample (firstname, lastname)
SELECT DISTINCT firstname, lastname FROM data
...
You could use a (temporary) table as data source instead of the CTE data
.
Related, with more details:
Something like this
with first_insert as (
insert into sample(firstname,lastname)
values('fai55','shaggk')
RETURNING id
),
second_insert as (
insert into sample1( id ,adddetails)
values
( (select id from first_insert), 'ss')
RETURNING user_id
)
insert into sample2 ( id ,adddetails)
values
( (select user_id from first_insert), 'ss');
As the generated id from the insert into sample2
is not needed, I removed the returning
clause from the last insert.
Typically, you'd use a transaction to avoid writing complicated queries.
http://www.postgresql.org/docs/current/static/sql-begin.html
http://dev.mysql.com/doc/refman/5.7/en/commit.html
You could also use a CTE, assuming your Postgres tag is correct. For instance:
with sample_ids as (
insert into sample(firstname, lastname)
values('fai55','shaggk')
RETURNING id
), sample1_ids as (
insert into sample1(id, adddetails)
select id,'ss'
from sample_ids
RETURNING id, user_id
)
insert into sample2(id, user_id, value)
select id, user_id, 'val'
from sample1_ids
RETURNING id, user_id;
You could create an after insert trigger on the Sample table to insert into the other two tables.
The only issue i see with doing this is that you wont have a way of inserting adddetails it will always be empty or in this case ss. There is no way to insert a column into sample thats not actualy in the sample table so you cant send it along with the innital insert.
Another option would be to create a stored procedure to run your inserts.
You have the question taged mysql and postgressql which database are we talking about here?
来源:https://stackoverflow.com/questions/20561254/insert-data-in-3-tables-at-a-time-using-postgres