SqlHelper 泛型方法，反射，支持实体类

最新推荐文章于 2021-01-21 05:38:44 发布

最新推荐文章于 2021-01-21 05:38:44 发布 · 465 阅读

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本文详细介绍了SQLHelper类的实现方式，包括如何通过该类执行SQL查询、执行SQL命令以及执行SQL存储过程等操作。重点阐述了如何将查询结果映射到指定类型的对象，以及如何使用泛型参数来提高代码的复用性和灵活性。

001
using System;

002
using System.Collections.Generic;

003
using System.Linq;

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using System.Text;

005
using System.Data;

006
using System.Data.SqlClient;

007
using System.Reflection;

008

009
namespace DAL

010{

011
public
class SqlHelper

012
{

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private
const string 
CONNECTION_STRING = @"server=.\sql2008;uid=sa;pwd=;database=BBSDB";

014

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private
static T ExecuteReader<T>(SqlDataReader dr)

016
{

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T obj =
default(T);

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obj = Activator.CreateInstance<T>();//T obj = new T();//instance

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Type type =
typeof(T);//get T class type by T's Name

020
PropertyInfo[] propertyInfos = type.GetProperties();//get current Type's all properties

021
int
fieldCount = dr.FieldCount;//get column count

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for
(int 
i = 0; i < fieldCount; i++)

023
{

024
string
fieldName = dr.GetName(i);//get column


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foreach
(PropertyInfo propertyInfo in
propertyInfos)

026
{//per property infoname

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string
properyName = propertyInfo.Name;//get property name

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if
(string.Compare(fieldName, properyName,
true) == 0)

029
{//column's name == propery's name

030
object
value = dr.GetValue(i);//get column's value

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if
(value != null 
&& value != DBNull.Value)

032
{

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propertyInfo.SetValue(obj, value,
null);//set property's value

034
}

035
break;

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}

037
}

038
}

039
return
obj;

040
}

041

042
public
static List<T> ExecuteList<T>(string
cmdText, CommandType commandType, params
SqlParameter[] args)

043
{

044
List<T> list =
new List<T>();

045
using
(SqlConnection con = new 
SqlConnection(CONNECTION_STRING))

046
{

047
using
(SqlCommand cmd = new 
SqlCommand(cmdText, con))

048
{

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cmd.CommandType = commandType;

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cmd.Parameters.AddRange(args);

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con.Open();

052
using
(SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection))

053
{

054
while
(dr.Read())

055
{

056
//dr.GetInt32(0);

057
//dr.GetString(1);

058
T obj = ExecuteReader<T>(dr);

059
list.Add(obj);

060
}

061
}

062
}

063
}

064
return
list;

065
}

066

067
public
static T ExecuteEntity<T>(string
cmdText, CommandType commandType, params
SqlParameter[] args)

068
{

069
T obj =
default(T);

070
using
(SqlConnection con = new 
SqlConnection(CONNECTION_STRING))

071
{

072
using
(SqlCommand cmd = new 
SqlCommand(cmdText, con))

073
{

074
cmd.CommandType = commandType;

075
cmd.Parameters.AddRange(args);

076
con.Open();

077
using
(SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection))

078
{

079
while
(dr.Read())

080
{

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obj = ExecuteReader<T>(dr);

082
break;

083
}

084
}

085
}

086
}

087
return
obj;

088
}

089

090
public
static int 
ExecuteNonQuery(string cmdText, CommandType commandType,
params SqlParameter[] args)

091
{

092
int
result = -1;

093
using
(SqlConnection con = new 
SqlConnection(CONNECTION_STRING))

094
{

095
using
(SqlCommand cmd = new 
SqlCommand(cmdText, con))

096
{

097
cmd.Parameters.AddRange(args);

098
cmd.CommandType = CommandType.StoredProcedure;

099
con.Open();

100
result = cmd.ExecuteNonQuery();

101
}

102
}

103
return
result;

104
}

105

106
}
107}