如何從 PostgreSQL 中的選擇查詢中將值插入到具有預設值的表中？

是否可以從語句中將INSERT值放入 PostgreSQL 表並為空列使用值？SELECT``DEFAULT

就我而言，該SELECT語句是從 JSON 中選擇的。

在下面的嘗試中，我通過顯式檢索序列而成功，但我希望有一種方法可以使用 DEFAULT 值插入。或者選擇預設值而無需顯式呼叫預設函式。

-- Example table
create table animals
(
   id serial,
   nm character varying (30) NOT NULL, --name
   typ character varying(10),
   tvi integer,
   tvf numeric(8,3)
);


insert into animals VALUES (DEFAULT,'mouse','m',4,12.45);

select row_to_json(a) from animals a;

select * from json_populate_record(null::animals,'{"id":null,"nm":"mouse","typ":"m","tvi":4,"tvf":12.450}');

--All good.


-- Attempt #1
INSERT INTO animals
select id ,nm,typ,tvi,tvf from json_populate_record(null::animals,'{"id":null,"nm":"mouse","typ":"m","tvi":4,"tvf":12.450}');

/*
ERROR:  null value in column "id" violates not-null constraint
DETAIL:  Failing row contains (null, mouse, m, 4, 12.450).
********** Error **********

ERROR: null value in column "id" violates not-null constraint
SQL state: 23502
Detail: Failing row contains (null, mouse, m, 4, 12.450).
*/


-- Attempt #2
INSERT INTO animals
select DEFAULT,nm,typ,tvi,tvf from json_populate_record(null::animals,'{"id":null,"nm":"mouse","typ":"m","tvi":4,"tvf":12.450}');

/*  I didn't  expect this to work, but it does illustrate what I am trying to accomplish
ERROR:  syntax error at or near "DEFAULT"
LINE 2: select DEFAULT,nm,typ,tvi,tvf from json_populate_record(null...
              ^
********** Error **********

ERROR: syntax error at or near "DEFAULT"
SQL state: 42601
Character: 28

*/


-- Attempt #3
INSERT INTO animals
select nextval('animals_id_seq'::regclass),nm,typ,tvi,tvf from json_populate_record(null::animals,'{"id":null,"nm":"mouse","typ":"m","tvi":4,"tvf":12.450}');

/*  This works, but I'm hoping for a way to accomplish this without knowing the underlying functions generating the default values.
Query returned successfully: one row affected, 11 msec execution time.
*/

select version();  --'PostgreSQL 9.5.1, compiled by Visual C++ build 1800, 64-bit'

如果在 Tablename 之後添加所有 ColumnsNames（不包括 ‘id’ 列），則會自動插入序列號，如：

INSERT INTO animals(nm,typ,tvi,tvf) select nm,typ,tvi,tvf from json_po..... 

如果列不在插入列列表中，您還可以在列中添加預設值以設置預設值。

如果要添加多條記錄：

insert into animals(nm,typ,tvi,tvf) 
select nm,typ,tvi,tvf 
from json_populate_recordset(null::animals, 
'
[
{"nm":"mouse","typ":"m","tvi":4,"tvf":12.450},
{"nm":"dog","typ":"x","tvi":10,"tvf":13.450}
]
');

引用自：https://dba.stackexchange.com/questions/134399