Postgresql: UUID的使用

默认安装的 Postgresql 是不带 UUID 函数的，为了生成一个 UUID，我们不得不在客户端生成。其实在 Postgresql 的安装目录下已经存在这样的函数定义，我们只需将其 import 进来即可。

在安装目录的 share/contrib 下面，可以找到 uuid-ossp.sql，使用以下命令：

p<a href="/tag/sql/" target="_blank" class="keywords">sql</a> -d pisces -U postgres -f D:/Service/Postgre<a href="/tag/sql/" target="_blank" class="keywords">sql</a>/9.0/share/contrib/uuid-o<a href="/tag/ssp/" target="_blank" class="keywords">ssp</a>.<a href="/tag/sql/" target="_blank" class="keywords">sql</a>

参数说明：

-d: 数据库名

-U: 用户名

-f: 要import的文件

以下截屏说明导入正确：

然后我们可以尝试用导入的函数生成一个UUID：

select uuid_generate_v4();

更多uuid函数，请在postgresql文档中搜索：

uuid-ossp

在C#中使用uuid类型的例子：

//--------------------------------------------------------------------------- // <<a href="/tag/cop/" target="_blank" class="keywords">cop</a>yright file="Program.cs" company="Xinsoft.org"> // <a href="/tag/cop/" target="_blank" class="keywords">cop</a>yright (c) Yaping Xin. All rights reserved. // </<a href="/tag/cop/" target="_blank" class="keywords">cop</a>yright> // <Description>Entry class for the testing.</Description> //--------------------------------------------------------------------------- namespace Org.Xinsoft.Demo.Postgre<a href="/tag/sql/" target="_blank" class="keywords">sql</a> { using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Data; using Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>; /// <summary> /// Entry class for the testing. /// </summary> internal class TestUuidProgram { /// <summary> /// Entry point for the testing. /// </summary> /// <p<a href="/tag/ara/" target="_blank" class="keywords">ara</a>m name="args">console arguments</p<a href="/tag/ara/" target="_blank" class="keywords">ara</a>m> internal static void Main(string[] args) { using (Databa<a href="/tag/SEO/" title="SEO">SEO</a>peration db = new Databa<a href="/tag/SEO/" title="SEO">SEO</a>peration()) { db.OpenConnection(); Console.WriteLine(db.ConnState); string <a href="/tag/sql/" target="_blank" class="keywords">sql</a> = "insert into demotable(id,name) values(@id,@name);"; using (Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>.Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>Command command = db.Connection.CreateCommand()) { command.CommandText = <a href="/tag/sql/" target="_blank" class="keywords">sql</a>; command.CommandType = CommandType.Text; command.P<a href="/tag/ara/" target="_blank" class="keywords">ara</a>meters.Add("@id",Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>Types.Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>DbType.Uuid); command.P<a href="/tag/ara/" target="_blank" class="keywords">ara</a>meters.Add("@name",Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>Types.Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>DbType.Varchar,25); command.Prepare(); for (int i = 0; i < 10; i++) { command.P<a href="/tag/ara/" target="_blank" class="keywords">ara</a>meters[0].Value = Guid.NewGuid(); command.P<a href="/tag/ara/" target="_blank" class="keywords">ara</a>meters[1].Value = string.Format("{0} {1}",i,DateTime.<a href="/tag/Now/" target="_blank" class="keywords">Now</a>.ToString("yyyy-MM-dd HH:mm:ss.fff")); int effects = command.ExecuteNonQuery(); Console.WriteLine(string.Format("INSERT: {0} rows effected.",effects)); } } <a href="/tag/sql/" target="_blank" class="keywords">sql</a> = "select id,name from demotable;"; using (Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>.Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>Command command = db.Connection.CreateCommand()) { command.CommandText = <a href="/tag/sql/" target="_blank" class="keywords">sql</a>; command.CommandType = CommandType.Text; command.Prepare(); DataTable result = DatabaseHelper.GetDataTable(command.ExecuteReader()); int rows = result.Rows.Count; int cols = result.Columns.Count; Console.WriteLine("Rows: {0}",rows); for (int i = 0; i < cols; i++) { Console.WriteLine("Column[{0}]: {1}/t| {2}",result.Columns[i].ColumnName,result.Columns[i].DataType.Name); } Console.WriteLine("Query result:"); for (int i = 0; i < rows; i++) { Da<a href="/tag/Taro/" target="_blank" class="keywords">Taro</a>w row = result.Rows[i]; for (int j = 0; j < cols; j++) { Console.Write("{0}/t",row[j].ToString()); } Console.WriteLine(string.Empty); } } <a href="/tag/sql/" target="_blank" class="keywords">sql</a> = "delete from demotable;"; using (Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>.Npg<a href="/tag/sql/" target="_blank" class="keywords">sql</a>Command command = db.Connection.CreateCommand()) { command.CommandText = <a href="/tag/sql/" target="_blank" class="keywords">sql</a>; command.CommandType = CommandType.Text; int effects = command.ExecuteNonQuery(); Console.WriteLine(string.Format("DELETE: {0} rows effected.",effects)); } db.CloseConnection(); } } } }

上述例子用到的表结构如下：

CREATE TABLE demotable ( id uuid NOT NULL,"name" ch<a href="/tag/ara/" target="_blank" class="keywords">ara</a>cter <a href="/tag/varying/" target="_blank" class="keywords">varying</a>(25),CONSTRAINT pk_demotable PRIMARY KEY (id) ) WITH ( OIDS=FALSE ); ALTER TABLE demotable OWNER TO agentusr;