Function with Insert according to a select that returns a list of ID’s - Postgresql

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Function with Insert according to a select that returns a list of ID’s - Postgresql

Asked 7 years ago

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I need to make a Rigger after insert calling a function that takes the last record inserted into a certain table and inserts the ID of that last record into another table according to a select that returns multiple ID’s. EX:

tb_1  
.-------------.
|  ID  | NOME |  
.-------------.    
|   1  |   A  | 
|   2  |   B  | 
|   3  |   C  | <- Último ID inserido  
'------'------' 

tb_2  
.-------------.
|  ID  | NOME |  
|------|------| 
|  41  |  AAA |  
|  42  |  BBB | 
|  43  |  CCC |  
|  44  |  AAA |  
|  45  |  AAA |  
'------'------'   

INSERT INTO tb_3 (tb_1_id,tb_2_id)  
VALUES (
        (SELECT MAX(ID) FROM tb_1), 
        (SELECT ID FROM tb_2 WHERE NOME = 'AAA')
       )  


tb_3  
.----------.----------.  
|  tb_1_id |  tb_2_id | 
|----------|----------| 
|     3    |    41    |
|     3    |    44    |
|     3    |    45    |
'----------'----------'

How to make a insert what makes this logic that I have shown? It is possible?
The structures of trigger and function I’ll do it later.

I don’t think it’s possible by Trigger because it’s two tables

– Motta

2017/06/07 at 18:33
You basically explained the behavior, it makes sense your logic to me. Try to do, if you have any problem ask a question of the respective problem.

– David

2017/06/08 at 01:27
I want to know if it is possible to make an Insert in this type, because the example I showed was wrong, but the logic is this.

– Spec4422

2017/06/08 at 19:04
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– Marcos Henzel

2017/06/14 at 13:42
Have you evaluated the use of the RETURNING clause of the INSERT command? I believe it can facilitate your procedure.

– anonimo

2019/05/03 at 22:10

2 answers

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by Athos Bonner • 36 points · Answer 1 · 2017-06-09T03:47:13+00:00

What you want to do is insert these ids in a link table, but from what I understand this tab_2 returns multiple ids, so in the end the insert gets like this:

INSERT INTO tb_3 (tb_1_id,1) 
INSERT INTO tb_3 (tb_1_id,2)
INSERT INTO tb_3 (tb_1_id,3)

Three ids of the tb_2 for the same id of db_1.

What you can do is a FOR who’s gonna walk this tab_2 (SELECT ID FROM tb_2 WHERE NOME = 'AAA'), in this your example will have three records, so just go inserting each one with your new id of tb_2 and the same id of tb_1.

EX:

FOR _table2 in (SELECT ID FROM tb_2 WHERE NOME = 'AAA')

LOOP

   INSERT INTO tb_3 (tb_1_id,tb_2_id) VALUES(SELECT MAX(ID) FROM tb_1,_table2.id)

END LOOP;

by Spec4422 • 11 points · Answer 2 · 2017-06-09T14:21:37+00:00

I found the solution in the simplest way and I have done several times. (so far I have not dropped the plug that I entered this world of loop just for this).

INSERT INTO tb_3 (tb_1_id, tb_2_id) (
     SELECT (SELECT MAX(ID) FROM tb_1) AS tb_1_id, ID AS tb_2_id 
       FROM tb_2 WHERE NOME = 'AAA')