PostgresSQL用returning实现mysql的last_insert_id

今天开发问到，postgressql里面有没有像mysql那样插入一个值后返回插入的值，这个是有的，而且有更强的扩展性。

 示例：

[postgres@localhost ~]$ psql
psql (9.2.4)
Type "help" for help.
postgres=# create table t_kenyon(id int,vname varchar(30),remark text);
CREATE TABLE
postgres=# insert into t_kenyon(id,vname) values(1,'test_kenyon') returning id;
 id
----
  1
(1 row)

INSERT 0 1
postgres=# insert into t_kenyon(id,vname) select generate_series(1,5),'Kenyon here' returning id;
 id
----
  1
  2
  3
  4
  5
(5 rows)

INSERT 0 5

扩展：
 a.返回更多的insert内容

postgres=# insert into t_kenyon(id,vname) select generate_series(6,8),'Kenyon here' returning id,vname;
 id |    vname
----+-------------
  6 | Kenyon here
  7 | Kenyon here
  8 | Kenyon here
(3 rows)

INSERT 0 3

postgres=# insert into t_kenyon(id,vname,remark) select generate_series(9,11),'Kenyon here','KENYON GOOD BOY!' returning *;
 id |    vname    |      remark
----+-------------+------------------
  9 | Kenyon here | KENYON GOOD BOY!
 10 | Kenyon here | KENYON GOOD BOY!
 11 | Kenyon here | KENYON GOOD BOY!
(3 rows)

INSERT 0 3

b.返回delete掉的数据

postgres=# select * from t_kenyon;
 id |    vname    |      remark
----+-------------+------------------
  1 | test_kenyon |
  1 | Kenyon here |
  2 | Kenyon here |
  3 | Kenyon here |
  4 | Kenyon here |
  5 | Kenyon here |
  6 | Kenyon here |
  7 | Kenyon here |
  8 | Kenyon here |
  9 | Kenyon here | KENYON GOOD BOY!
 10 | Kenyon here | KENYON GOOD BOY!
 11 | Kenyon here | KENYON GOOD BOY!
(12 rows)

postgres=# delete from t_kenyon where id >9 returning id,vname;
 id |    vname
----+-------------
 10 | Kenyon here
 11 | Kenyon here
(2 rows)

DELETE 2
postgres=# delete from t_kenyon where id <5 returning *;
 id |    vname    | remark
----+-------------+--------
  1 | test_kenyon |
  1 | Kenyon here |
  2 | Kenyon here |
  3 | Kenyon here |
  4 | Kenyon here |
(5 rows)

DELETE 5
postgres=# select * from t_kenyon;
 id |    vname    |      remark
----+-------------+------------------
  5 | Kenyon here |
  6 | Kenyon here |
  7 | Kenyon here |
  8 | Kenyon here |
  9 | Kenyon here | KENYON GOOD BOY!
(5 rows)

c.返回update掉的数据

postgres=# update t_kenyon set remark = 'kenyon bad boy!' where id <7 returning id,remark;
 id |     remark
----+-----------------
  5 | kenyon bad boy!
  6 | kenyon bad boy!
(2 rows)

UPDATE 2

mysql的last_insert_id使用有诸多限制和注意的地方，如字段需要auto_increment，一个SQL插入多个值的时候只会返回第一个id值，此不再叙述。