Npgsql使用入门(二)【实用助手类】

数据库映射的实体类:

public class Test
{
public long TestID { get; set; }
public string Name { get; set; }
public int Age { get; set; }
}

public class TestLink
{
public int TestLinkID { get; set; }
public long TestID { get; set; }
public string LinkName { get; set; }
}

public class customer
{
public long customer_id { get; set; }
public int age { get; set; }
public string name { get; set; }
}

public class order
{
public int order_id { get; set; }
public int customer_id { get; set; }
public string item { get; set; }
public string shipping_address { get; set; }
}

/// <summary>
/// 实体 company
/// </summary>
[Description("Primary:id")]
[Serializable]
public class Company
{

#region 私有变量
private Int32 _id = Int32.MinValue;
private string _name = null;
private Int32 _age = Int32.MinValue;
private string _address = null;
private float _salary = float.MinValue;
private DateTime _join_date = DateTime.MinValue;
#endregion

#region 公共属性
/// <summary>
/// 主键 id(NOT NULL)
/// </summary>
public Int32 id
{
set { _id = value; }
get { return _id; }
}
/// <summary>
/// name(NOT NULL)
/// </summary>
public string name
{
set { _name = value; }
get { return _name; }
}
/// <summary>
/// age(NOT NULL)
/// </summary>
public Int32 age
{
set { _age = value; }
get { return _age; }
}
/// <summary>
/// address
/// </summary>
public string address
{
set { _address = value; }
get { return _address; }
}
/// <summary>
/// salary
/// </summary>
public float salary
{
set { _salary = value; }
get { return _salary; }
}
/// <summary>
/// join_date
/// </summary>
public DateTime join_date
{
set { _join_date = value; }
get { return _join_date; }
}
#endregion

}

Program.cs代码:

public class Program
{
static void Main(string[] args)
{
using (var dc = new NpgSqlDataContext("Host=localhost;Username=king;Password=wu12345;Database=dellstore").MapComposite<Company>("company"))
{
var r0 = dc.Query(@"SELECT * FROM company");
PrintTable(r0);

//-------------------------------------------------------------------------------------------------

var r1 = dc.Query(@"SELECT * FROM company where id=@id", new NpgsqlParameter("id", 3));
PrintTable(r1);
//-------------------------------------------------------------------------------------------------

// 使用表值参数
// Postgres 没有tvp - 它们由正则或复合类型的数组
var r3 = dc.Query(@" SELECT c.*   FROM company c  INNER JOIN UNNEST(@ageval_tvp) tvp ON  c.age = tvp", new NpgsqlParameter("ageval_tvp", new int[] { 1,3, 4}));
PrintTable(r3);
//-------------------------------------------------------------------------------------------------

// 复合型tvp
dc.MapComposite<Company>("company");
var r4 = dc.Query(@" SELECT c.*  FROM company c  INNER JOIN UNNEST(@x_company) x ON  c.age = x.age AND  c.name = x.name",
new NpgsqlParameter(
"x_company",
new Company[] {
new Company() { name = "Paul", age = 32 },
new Company() { name = "Allen", age = 25 }
}
)
);
PrintTable(r4);
//-------------------------------------------------------------------------------------------------

dc.MapComposite<order>("orders");
var r6 = dc.Query(@"INSERT INTO orders (order_id,customer_id, item,shipping_address) SELECT order_id,customer_id, item,shipping_address from UNNEST(@x_orders) returning order_id",
new NpgsqlParameter(
"x_orders",
new order[] {
new order() {order_id=1, customer_id = 22, item = "cc",shipping_address="加利福尼亚硅谷1号" },
new order() {order_id=2,customer_id = 23, item = "dd",shipping_address="中国上海外滩18号" }
})
);
PrintTable(r6);
//-------------------------------------------------------------------------------------------------

//Console.ReadKey();

var r7 = dc.Execute(@"WITH customer as (insert into customers(name, age) values ('Ghan', 55) returning customer_id)INSERT INTO orders(customer_id, item)SELECT c.customer_id, x.item FROM customer c CROSS JOIN UNNEST(@x_orders) x
",
new NpgsqlParameter(
"x_orders",
new order[] {
new order() { item = "gg" },
new order() { item = "hh" }
}
)
);
Console.WriteLine("Inserted {0} rows", r7);

//-------------------------------------------------------------------------------------------------

//区分大小写的名称
var query = @"
WITH Customer AS (INSERT INTO ""Test"" (""Name"", ""Age"")
SELECT ""Name"", ""Age""
FROM UNNEST(@TestItems) returning ""TestID"")
INSERT INTO ""TestLink"" (""TestID"")
SELECT c.""TestID"" FROM Customer c
";

var query1 = @"
WITH Customer AS (INSERT INTO ""Test"" (""Name"", ""Age"")
SELECT ""Name"", ""Age""
FROM UNNEST(@TestItems) returning ""TestID"")
INSERT INTO ""TestLink"" (""TestID"", ""LinkName"")
SELECT c.""TestID"", x.""LinkName"" FROM Customer c CROSS JOIN UNNEST (@TestLinkItems) x
";

var x = dc.Execute(query,new NpgsqlParameter("TestItems", new Test[] { new Test() { Name = "Sam", Age = 25 } }));

Console.WriteLine("已插入行 {0}", x);
//-------------------------------------------------------------------------------------------------

var y = dc.Execute(query1,
new NpgsqlParameter(
"TestItems",
new Test[] { new Test() { Name = "Sam", Age = 25 } }),
new NpgsqlParameter(
"TestLinkItems",
new TestLink[]
{
new TestLink() {LinkName = "xxx"},
new TestLink() {LinkName = "yyy"}
}));

Console.WriteLine("已插入行 {0}", y);

}
Console.ReadKey();
}

static void PrintTable(DataTable t)
{
foreach (var c in t.Columns.Cast<DataColumn>().Select(r => r.ColumnName))
Console.Write("{0,12}", c);
Console.WriteLine();

foreach (var r in t.Rows.Cast<DataRow>())
{
foreach (var c in r.ItemArray)
{
int length=c.ToString().Length;
Console.Write("{0,12}", length > 10 ? c.ToString().Substring(0, 10) : c.ToString());
}

Console.WriteLine();
}
Console.WriteLine("\n");
Console.WriteLine("-----------------------------------------------------------------------------");
}
}

CaseSensitiveTranslator.cs代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Npgsql;

namespace NpgSqlUtils
{
public class CaseSensitiveTranslator : INpgsqlNameTranslator
{
public string TranslateMemberName(string clrName)
{
return clrName;
}

public string TranslateTypeName(string clrName)
{
return clrName;
}
}
}

INpgSqlDataContext.cs代码:

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Npgsql;

namespace NpgSqlUtils
{
public interface INpgSqlDataContext: IDisposable
{
INpgsqlNameTranslator Translator { get; }
DataTable Query(string query, params NpgsqlParameter[] parameters);
int Execute(string query, params NpgsqlParameter[] parameters);

/// <summary>
///
/// </summary>
INpgSqlDataContext MapComposite<T>(string name) where T : new();
}
}

NpgSqlDataContext.cs代码:

using Npgsql;
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace NpgSqlUtils
{
public class NpgSqlDataContext : INpgSqlDataContext
{
private NpgsqlConnection _connection;

public INpgsqlNameTranslator Translator { get; set; }

public NpgSqlDataContext(string connectionString, INpgsqlNameTranslator translator = null)
{
if (translator == null)
translator = new CaseSensitiveTranslator();

Translator = translator;

_connection = new NpgsqlConnection(connectionString);
_connection.Open();
}

public DataTable Query(string query, params NpgsqlParameter[] parameters)
{
DataTable result;
using (NpgsqlCommand cmd = new NpgsqlCommand())
{
cmd.Connection = _connection;
cmd.CommandText = query;
cmd.Parameters.AddRange(parameters);

using (var reader = cmd.ExecuteReader())
{
result = new DataTable();
result.Load(reader);
}
}

return result;
}

public int Execute(string query, params NpgsqlParameter[] parameters)
{
int result = -1;
using (NpgsqlCommand cmd = new NpgsqlCommand())
{
cmd.Connection = _connection;
cmd.CommandText = query;
cmd.Parameters.AddRange(parameters);
result = cmd.ExecuteNonQuery();
}

return result;
}

public void Dispose()
{
_connection.Dispose();
}

public INpgSqlDataContext MapComposite<T>(string name) where T : new()
{
_connection.MapComposite<T>(name, Translator);
return this;
}
}
}

SQL脚本:

-- Table: public.company

-- DROP TABLE public.company;

CREATE TABLE public.company
(
id integer NOT NULL,
name text COLLATE pg_catalog."default" NOT NULL,
age integer NOT NULL,
address character(50) COLLATE pg_catalog."default",
salary real,
join_date date,
CONSTRAINT company_pkey PRIMARY KEY (id)
)
WITH (
OIDS = FALSE
)
TABLESPACE pg_default;

ALTER TABLE public.company
OWNER to postgres;

-- Table: public.orders

-- DROP TABLE public.orders;

CREATE TABLE public.orders
(
order_id integer NOT NULL,
shipping_address text COLLATE pg_catalog."default",
item text COLLATE pg_catalog."default",
customer_id integer,
CONSTRAINT orders_pkey PRIMARY KEY (order_id)
)
WITH (
OIDS = FALSE
)
TABLESPACE pg_default;

ALTER TABLE public.orders
OWNER to postgres;

运行结果如图: