我，试图插入一行到PostgreSQL的表串行主键，我需要检索此列插入之后。我是这样的：

I', trying to insert a row into a PostgreSQL table with a serial primary key and I need to retrieve this column after it was inserted. I got something like this:

表国家报有3列：ID，派斯，资本; id是一个串行列，是它的主键。

The table "pais" has 3 columns: id, pais, capital; id is a serial column and is its primary key.

NpgsqlCommand query = new NpgsqlCommand("insert into pais(nombre, capital) values(@nombre, @capital)", conn);
query.Parameters.Add(new NpgsqlParameter("nombre", NpgsqlDbType.Varchar));
query.Parameters.Add(new NpgsqlParameter("capital", NpgsqlDbType.Varchar));
query.Prepare();
query.Parameters[0].Value = this.textBox1.Text;
query.Parameters[1].Value = this.textBox2.Text;
Object res = query.ExecuteScalar();
Console.WriteLine(res);

它插入该行的表，但资源的价值是零。如果我插入的nexval（'table_sequence）也将返回null。

It inserts the row on the table but "res" value is null. If I insert with the nexval('table_sequence') also returns null.

我怎么可以返回表的ID你知道吗？我失去了一些东西？

Any idea of how can I return the id of the table? I am missing something?

在此先感谢

推荐答案

为了选择插入你需要使用的最后一个标识： CURRVAL（sequencename）

In order to select the last identity inserted you need to use: currval(sequencename)

让你的SELECT语句应该是这样的：

so your select statement should look like:

NpgsqlCommand query = new NpgsqlCommand("insert into pais(nombre, capital) values(@nombre, @capital);select currval('table_sequence');", conn);

您可以找到这个多在的http://www.programmingado.net/a-117/Insert-data-and-retrieve-serial-autonumber-id.aspx

干杯，

CEC