利用反射自动生成SQL语句（仿Linq）

转：http://www.cnblogs.com/the7stroke/archive/2012/04/22/2465597.html

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Reflection;

using System.Data;

public class SQLHelper

{

/// <summary>

/// 插入单个实例

/// </summary>

/// <typeparam name="T"></typeparam>

/// <param name="entity"></param>

/// <returns></returns>

public static int Insert<T>(T entity)

{

#region 生成 SQL 语句

Type type = typeof(T);

string sql = "INSERT INTO [" + type.Name + "] (";

string colsName = string.Empty;

string colsValues = string.Empty;

foreach (PropertyInfo item in type.GetProperties())

{

if (item.Name.ToLower() == "id")          //不插入自动增长列

continue;

if (item.GetValue(entity, null) == null)    //null值也不插入

continue;

colsName += "[" + item.Name + "],";

if (item.PropertyType.ToString().Contains("String") || item.PropertyType.ToString().Contains("Date"))

colsValues += "'" + item.GetValue(entity, null) + "',";

else

colsValues += item.GetValue(entity, null) + ",";

}

colsName = colsName.Substring(0, colsName.LastIndexOf(','));        //不要最后一个 ,

colsValues = colsValues.Substring(0, colsValues.LastIndexOf(','));  //不要最后一个 ,

sql += colsName + ") VALUES ( " + colsValues + ")";

#endregion

return DBHelperSQL.ExecuteNonQuery(sql);

}

/// <summary>

/// 插入多个实例

/// </summary>

/// <typeparam name="T"></typeparam>

/// <param name="ListEntity"></param>

public static void Insert<T>(List<T> ListEntity)

{

#region 生成 SQL 语句

List<string> sqlList = new List<string>();

foreach (var entity in ListEntity)

{

Type type = entity.GetType();

string sql = "INSERT INTO [" + type.Name + "] (";

string colsName = string.Empty;

string colsValues = string.Empty;

foreach (PropertyInfo item in type.GetProperties())

{

if (item.Name.ToLower() == "id")          //不插入自动增长列

continue;

if (item.GetValue(entity, null) == null)    //null值也不插入

continue;

colsName += "[" + item.Name + "],";

if (item.PropertyType.ToString().Contains("String") || item.PropertyType.ToString().Contains("Date"))

colsValues += "'" + item.GetValue(entity, null) + "',";

else

colsValues += item.GetValue(entity, null) + ",";

}

colsName = colsName.Substring(0, colsName.LastIndexOf(','));        //不要最后一个 ,

colsValues = colsValues.Substring(0, colsValues.LastIndexOf(','));  //不要最后一个 ,

sql += colsName + ") VALUES ( " + colsValues + ");";

sqlList.Add(sql);

}

#endregion

DBHelperSQL.ExcuteTransactionSql(sqlList);

}

/// <summary>

/// 删除单个实例

/// </summary>

/// <typeparam name="T"></typeparam>

/// <param name="Id"></param>

/// <returns></returns>

public static int Delete<T>(int Id)

{

Type type = typeof(T);

string sql = "DELETE [" + type.Name + "] WHERE Id IN ( " + Id + ")";

return DBHelperSQL.ExecuteNonQuery(sql);

}

/// <summary>

/// 删除单个实例

/// </summary>

/// <typeparam name="T"></typeparam>

/// <param name="Id"></param>

/// <returns></returns>

public static int Delete<T>(T entity)

{

Type type = typeof(T);

string sql = "DELETE [" + type.Name + "] WHERE Id IN ( ";

foreach (PropertyInfo item in type.GetProperties())

{

if (item.Name.ToLower() == "id")          //不插入自动增长列

{

sql += item.GetValue(entity,null) + ")";

break;

}

}

return DBHelperSQL.ExecuteNonQuery(sql);

}

/// <summary>

/// 删除多个实体

/// </summary>

/// <typeparam name="T">实体类型</typeparam>

/// <param name="Ids">Id 数组</param>

/// <returns></returns>

public static int Delete<T>(int[] Ids)

{

Type type = typeof(T);

string sql = "DELETE [" + type.Name + "] WHERE Id IN ( ";

foreach (var item in Ids)

{

sql +=  Ids + ",";

}

sql = sql.Substring(0, sql.LastIndexOf(','));   //不要最后一个 ，

sql += " )";

return DBHelperSQL.ExecuteNonQuery(sql);

}

/// <summary>

/// 删除多个实体

/// </summary>

/// <typeparam name="T"></typeparam>

/// <param name="listEntity">实体数组</param>

/// <returns></returns>

public static int Delete<T>(List<T> listEntity)

{

if (listEntity == null || listEntity.Count == 0)

{

return 0;

}

Type type = typeof(T);

string sql = "DELETE [" + type.Name + "] WHERE Id IN ( ";

foreach (var entity in listEntity)

{

foreach (PropertyInfo property in entity.GetType().GetProperties())

{

if (property.Name.ToLower() == "id")          //不插入自动增长列

{

sql += property.GetValue(entity, null) + ",";

break;

}

}

}

sql = sql.Substring(0, sql.LastIndexOf(','));  //不要最后一个 ，

sql += " )";

return DBHelperSQL.ExecuteNonQuery(sql);

}

/// <summary>

/// 修改单个实例

/// </summary>

/// <typeparam name="T"></typeparam>

/// <param name="entity"></param>

/// <returns></returns>

public static int Update<T>(T entity)

{

#region 生成 SQL 语句

Type type = typeof(T);

string sql = "UPDATE [" + type.Name + "] SET ";

object ID = 0;

foreach (PropertyInfo item in type.GetProperties())

{

if (item.Name.ToLower() == "id")          //不插入自动增长列

{

ID = item.GetValue(entity, null);

continue;

}

if (item.GetValue(entity, null) == null)    //null值也不插入

continue;

sql += "[" + item.Name + "]=";

if (item.PropertyType.ToString().Contains("String") || item.PropertyType.ToString().Contains("Date"))

sql += "'" + item.GetValue(entity, null) + "',";

else

sql += item.GetValue(entity, null) + ",";

}

sql = sql.Substring(0, sql.LastIndexOf(','));        //不要最后一个,

sql += " WHERE ID=" + ID;

#endregion

return DBHelperSQL.ExecuteNonQuery(sql);

}

/// <summary>

/// 根据ID获取单个实例

/// </summary>

/// <typeparam name="T"></typeparam>

/// <param name="ID"></param>

/// <returns></returns>

public static T Get<T>(int ID)

{

#region 生成 SQL 语句

Type type = typeof(T);

string sql = "SELECT * FROM [" + type.Name + "] WHERE ID=" + ID;

#endregion

return DBHelperSQL.ExecuteDataTable(sql).ToSingleEntity<T>();

}

/// <summary>

/// 获取所有实例

/// </summary>

/// <typeparam name="T"></typeparam>

/// <returns></returns>

public static List<T> Get<T>()

{

#region 生成 SQL 语句

Type type = typeof(T);

string sql = "SELECT * FROM [" + type.Name + "]";

#endregion

return DBHelperSQL.ExecuteDataTable(sql).ToListEntity<T>();

}

/// <summary>

/// 根据条件查询得到多个实例 (不分页)

/// </summary>

/// <typeparam name="T"></typeparam>

/// <param name="condition"></param>

/// <returns></returns>

public static List<T> Get<T>(T condition)

{

#region 生成 SQL 语句

Type type = typeof(T);

string sql = "SELECT * FROM [" + type.Name + "] WHERE 1=1";

foreach (PropertyInfo item in type.GetProperties())

{

#region 不加条件处理

if (item.GetValue(condition, null) == null)    //null值 不加条件

continue;

if (item.PropertyType.ToString().Contains("Int"))   //整形为 -1 时不加条件

{

if (item.GetValue(condition, null).ToString().Equals("-1"))

{

continue;

}

}

else if (item.PropertyType.ToString().Contains("Decimal"))   //整形为 -1 时不加条件

{

if (item.GetValue(condition, null).ToString().Equals("-1"))

{

continue;

}

}

#endregion

sql += " AND [" + item.Name + "] ";

if (item.PropertyType.ToString().Contains("String") )       //字符串形用模糊查询

sql += " LIKE "+ "'%" + item.GetValue(condition, null) + "%'";

else if (item.PropertyType.ToString().Contains("Date")){    //日期类型

}else{

sql += " = "+ item.GetValue(condition, null) + "";

}

}

#endregion

return DBHelperSQL.ExecuteDataTable(sql).ToListEntity<T>();

}

/// <summary>

/// 根据条件查询得到多个实例 (带分页)

/// </summary>

/// <typeparam name="T"></typeparam>

/// <param name="condition"></param>

/// <returns></returns>

public static List<T> Get<T>(T condition, int pageIndex, int pageSize, ref int totalCount)

{

#region 生成 SQL 语句

Type type = typeof(T);

string sql = "SELECT TOP " + pageSize + " * FROM [" + type.Name + "] WHERE (ID NOT IN (SELECT TOP " + (pageIndex - 1) * pageSize + " ID FROM [" + type.Name + "] WHERE 1=1 ";

StringBuilder sb = new StringBuilder();

foreach (PropertyInfo item in type.GetProperties())

{

#region 不加条件处理

if (item.GetValue(condition, null) == null)    //null值 不加条件

continue;

if (item.PropertyType.ToString().Contains("Int"))   //整形为 -1 时不加条件

{

if (item.GetValue(condition, null).ToString().Equals("-1"))

{

continue;

}

}

else if (item.PropertyType.ToString().Contains("Decimal"))   //整形为 -1 时不加条件

{

if (item.GetValue(condition, null).ToString().Equals("-1"))

{

continue;

}

}

#endregion

sb.Append(" AND [" + item.Name + "] ");

if (item.PropertyType.ToString().Contains("String"))       //字符串形用模糊查询

sql += " LIKE " + "'%" + item.GetValue(condition, null) + "%'";

else if (item.PropertyType.ToString().Contains("Date"))

{    //日期类型

}

else

{

sql += " = " + item.GetValue(condition, null) + "";

}

}

sql += sb.ToString() + "ORDER BY ID ))  ORDER BY ID ";

//总记录数

string sqlForCount = "SELECT COUNT(*) FROM [" + type.Name + "] WHERE 1=1 " + sb.ToString();

string count = DBHelperSQL.ExecuteString(sqlForCount);

totalCount = string.IsNullOrEmpty(count) ? 0 : int.Parse(count);

#endregion

return DBHelperSQL.ExecuteDataTable(sql).ToListEntity<T>();

}

}