现在用的EF比较多，渐渐的ADO.NET比较少用了。
今天就当做是SqlHelper的小小总结。
SqlHelper.cs
using System;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Net.Sockets;
namespace Utility
{
///
/// SQL Server数据库访问助手类
/// 本类为静态类 不可以被实例化 需要使用时直接调用即可
/// Copyright © 2013 Wedn.Net
///
public static partial class SqlHelper
{
private static readonly string[] localhost = new[] { "localhost", ".", "(local)" };
///
/// 数据库连接字符串
///
private readonly static string connStr;
static SqlHelper()
{
var conn = System.Configuration.ConfigurationManager.ConnectionStrings["ConnStr"];
if (conn!=null)
{
connStr = conn.ConnectionString;
}
}
#region 数据库检测
#region 测试数据库服务器连接 +static bool TestConnection(string host, int port, int millisecondsTimeout)
/// <summary>
/// 采用Socket方式，测试数据库服务器连接
/// </summary>
/// <param name="host">服务器主机名或IP</param>
/// <param name="port">端口号</param>
/// <param name="millisecondsTimeout">等待时间：毫秒</param>
/// <exception cref="Exception">链接异常</exception>
/// <returns></returns>
public static bool TestConnection(string host, int port, int millisecondsTimeout)
{
host = localhost.Contains(host) ? "127.0.0.1" : host;
using (var client = new TcpClient())
{
try
{
var ar = client.BeginConnect(host, port, null, null);
ar.AsyncWaitHandle.WaitOne(millisecondsTimeout);
return client.Connected;
}
catch (Exception)
{
throw;
}
}
}
#endregion
#region 检测表是否存在 + static bool ExistsTable(string table)
/// <summary>
/// 检测表是否存在
/// </summary>
/// <param name="table">要检测的表名</param>
/// <returns></returns>
public static bool ExistsTable(string table)
{
string sql = "select count(1) from sysobjects where id = object_id(N'[" + table + "]') and OBJECTPROPERTY(id, N'IsUserTable') = 1";
//string strsql = "SELECT count(*) FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[" + TableName + "]') AND type in (N'U')";
object res = ExecuteScalar(sql);
return (Object.Equals(res, null)) || (Object.Equals(res, System.DBNull.Value));
}
#endregion
#region 判断是否存在某张表的某个字段 +static bool ExistsColumn(string table, string column)
/// <summary>
/// 判断是否存在某张表的某个字段
/// </summary>
/// <param name="table">表名称</param>
/// <param name="column">列名称</param>
/// <returns>是否存在</returns>
public static bool ExistsColumn(string table, string column)
{
string sql = "select count(1) from syscolumns where [id]=object_id('N[" + table + "]') and [name]='" + column + "'";
object res = ExecuteScalar(sql);
if (res == null)
return false;
return Convert.ToInt32(res) > 0;
}
#endregion
#region 判断某张表的某个字段中是否存在某个值 +static bool ColumnExistsValue(string table, string column, string value)
/// <summary>
/// 判断某张表的某个字段中是否存在某个值
/// </summary>
/// <param name="table">表名称</param>
/// <param name="column">列名称</param>
/// <param name="value">要判断的值</param>
/// <returns>是否存在</returns>
public static bool ColumnExistsValue(string table, string column, string value)
{
string sql = "SELECT count(1) FROM [" + table + "] WHERE [" + column + "]=@Value;";
object res = ExecuteScalar(sql, new SqlParameter("@Value", value));
if (res == null)
return false;
return Convert.ToInt32(res) > 0;
}
#endregion
#endregion
#region 公共方法
#region 获取指定表中指定字段的最大值, 确保字段为INT类型
/// <summary>
/// 获取指定表中指定字段的最大值, 确保字段为INT类型
/// </summary>
/// <param name="fieldName">字段名</param>
/// <param name="tableName">表名</param>
/// <returns>最大值</returns>
public static int QueryMaxId(string fieldName, string tableName)
{
string sql = string.Format("select max([{0}]) from [{1}];", fieldName, tableName);
object res = ExecuteScalar(sql);
if (res == null)
return 0;
return Convert.ToInt32(res);
}
#endregion
#region 生成查询语句
#region 生成分页查询数据库语句 +static string GenerateQuerySql(string table, string[] columns, int index, int size, string wheres, string orderField, bool isDesc = true)
/// <summary>
/// 生成分页查询数据库语句, 返回生成的T-SQL语句
/// </summary>
/// <param name="table">表名</param>
/// <param name="columns">列集合, 多个列用英文逗号分割(colum1,colum2...)</param>
/// <param name="index">页码(即第几页)(传入-1则表示忽略分页取出全部)</param>
/// <param name="size">显示页面大小(即显示条数)</param>
/// <param name="where">条件语句(忽略则传入null)</param>
/// <param name="orderField">排序字段(即根据那个字段排序)(忽略则传入null)</param>
/// <param name="isDesc">排序方式(0:降序(desc)|1:升序(asc))(忽略则传入-1)</param>
/// <returns>生成的T-SQL语句</returns>
public static string GenerateQuerySql(string table, string[] columns, int index, int size, string where, string orderField, bool isDesc = true)
{
if (index == 1)
{
// 生成查询第一页SQL
return GenerateQuerySql(table, columns, size, where, orderField, isDesc);
}
if (index < 1)
{
// 取全部数据
return GenerateQuerySql(table, columns, where, orderField, isDesc);
}
if (string.IsNullOrEmpty(orderField))
{
throw new ArgumentNullException("orderField");
}
// 其他情况, 生成row_number分页查询语句
// SQL模版
const string format = @"select {0} from
(
select ROW_NUMBER() over(order by [{1}] {2}) as num, {0} from [{3}] {4}
)
as tbl
where
tbl.num between ({5}-1)*{6} + 1 and {5}*{6};";
// where语句组建
where = string.IsNullOrEmpty(where) ? string.Empty : "where " + where;
// 查询字段拼接
string column = columns != null && columns.Any() ? string.Join(" , ", columns) : "*";
return string.Format(format, column, orderField, isDesc ? "desc" : string.Empty, table, where, index, size);
}
#endregion
#region 生成查询数据库语句查询全部 +static string GenerateQuerySql(string table, string[] columns, string wheres, string orderField, bool isDesc = true)
/// <summary>
/// 生成查询数据库语句查询全部, 返回生成的T-SQL语句
/// </summary>
/// <param name="table">表名</param>
/// <param name="columns">列集合</param>
/// <param name="where">条件语句(忽略则传入null)</param>
/// <param name="orderField">排序字段(即根据那个字段排序)(忽略则传入null)</param>
/// <param name="isDesc">排序方式(0:降序(desc)|1:升序(asc))(忽略则传入-1)</param>
/// <returns>生成的T-SQL语句</returns>
public static string GenerateQuerySql(string table, string[] columns, string where, string orderField, bool isDesc = true)
{
// where语句组建
where = string.IsNullOrEmpty(where) ? string.Empty : "where " + where;
// 查询字段拼接
string column = columns != null && columns.Any() ? string.Join(" , ", columns) : "*";
const string format = "select {0} from [{1}] {2} {3} {4}";
return string.Format(format, column, table, where,
string.IsNullOrEmpty(orderField) ? string.Empty : "order by " + orderField,
isDesc && !string.IsNullOrEmpty(orderField) ? "desc" : string.Empty);
}
#endregion
#region 生成分页查询数据库语句查询第一页 +static string GenerateQuerySql(string table, string[] columns, int size, string where, string orderField, bool isDesc = true)
/// <summary>
/// 生成分页查询数据库语句查询第一页, 返回生成的T-SQL语句
/// </summary>
/// <param name="table">表名</param>
/// <param name="columns">列集合</param>
/// <param name="size">显示页面大小(即显示条数)</param>
/// <param name="where">条件语句(忽略则传入null)</param>
/// <param name="orderField">排序字段(即根据那个字段排序)(忽略则传入null)</param>
/// <param name="isDesc">排序方式(0:降序(desc)|1:升序(asc))(忽略则传入-1)</param>
/// <returns>生成的T-SQL语句</returns>
public static string GenerateQuerySql(string table, string[] columns, int size, string where, string orderField, bool isDesc = true)
{
// where语句组建
where = string.IsNullOrEmpty(where) ? string.Empty : "where " + where;
// 查询字段拼接
string column = columns != null && columns.Any() ? string.Join(" , ", columns) : "*";
const string format = "select top {0} {1} from [{2}] {3} {4} {5}";
return string.Format(format, size, column, table, where,
string.IsNullOrEmpty(orderField) ? string.Empty : "order by " + orderField,
isDesc && !string.IsNullOrEmpty(orderField) ? "desc" : string.Empty);
}
#endregion
#endregion
#region 将一个SqlDataReader对象转换成一个实体类对象 +static TEntity MapEntity<TEntity>(SqlDataReader reader) where TEntity : class,new()
/// <summary>
/// 将一个SqlDataReader对象转换成一个实体类对象
/// </summary>
/// <typeparam name="TEntity">实体类型</typeparam>
/// <param name="reader">当前指向的reader</param>
/// <returns>实体对象</returns>
public static TEntity MapEntity<TEntity>(SqlDataReader reader) where TEntity : class,new()
{
try
{
var props = typeof(TEntity).GetProperties();
var entity = new TEntity();
foreach (var prop in props)
{
if (prop.CanWrite)
{
try
{
var index = reader.GetOrdinal(prop.Name);
var data = reader.GetValue(index);
if (data != DBNull.Value)
{
prop.SetValue(entity, Convert.ChangeType(data, prop.PropertyType), null);
}
}
catch (IndexOutOfRangeException)
{
continue;
}
}
}
return entity;
}
catch
{
return null;
}
}
#endregion
#endregion
#region SQL执行方法
#region ExecuteNonQuery +static int ExecuteNonQuery(string cmdText, params SqlParameter[] parameters)
/// <summary>
/// 执行一个非查询的T-SQL语句，返回受影响行数，如果执行的是非增、删、改操作，返回-1
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="parameters">参数列表</param>
/// <exception cref="链接数据库异常"></exception>
/// <returns>受影响的行数</returns>
public static int ExecuteNonQuery(string cmdText, params SqlParameter[] parameters)
{
return ExecuteNonQuery(cmdText, CommandType.Text, parameters);
}
#endregion
#region ExecuteNonQuery +static int ExecuteNonQuery(string cmdText, CommandType type, params SqlParameter[] parameters)
/// <summary>
/// 执行一个非查询的T-SQL语句，返回受影响行数，如果执行的是非增、删、改操作，返回-1
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="type">命令类型</param>
/// <param name="parameters">参数列表</param>
/// <exception cref="链接数据库异常"></exception>
/// <returns>受影响的行数</returns>
public static int ExecuteNonQuery(string cmdText, CommandType type, params SqlParameter[] parameters)
{
using (SqlConnection conn = new SqlConnection(connStr))
{
using (SqlCommand cmd = new SqlCommand(cmdText, conn))
{
if (parameters != null)
{
cmd.Parameters.Clear();
cmd.Parameters.AddRange(parameters);
}
cmd.CommandType = type;
try
{
conn.Open();
int res = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return res;
}
catch (System.Data.SqlClient.SqlException e)
{
conn.Close();
throw e;
}
}
}
}
#endregion
#region ExecuteScalar +static object ExecuteScalar(string cmdText, params SqlParameter[] parameters)
/// <summary>
/// 执行一个查询的T-SQL语句，返回第一行第一列的结果
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="parameters">参数列表</param>
/// <exception cref="链接数据库异常"></exception>
/// <returns>返回第一行第一列的数据</returns>
public static object ExecuteScalar(string cmdText, params SqlParameter[] parameters)
{
return ExecuteScalar(cmdText, CommandType.Text, parameters);
}
#endregion
#region ExecuteScalar +static object ExecuteScalar(string cmdText, CommandType type, params SqlParameter[] parameters)
/// <summary>
/// 执行一个查询的T-SQL语句，返回第一行第一列的结果
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="type">命令类型</param>
/// <param name="parameters">参数列表</param>
/// <exception cref="链接数据库异常"></exception>
/// <returns>返回第一行第一列的数据</returns>
public static object ExecuteScalar(string cmdText, CommandType type, params SqlParameter[] parameters)
{
using (SqlConnection conn = new SqlConnection(connStr))
{
using (SqlCommand cmd = new SqlCommand(cmdText, conn))
{
if (parameters != null)
{
cmd.Parameters.Clear();
cmd.Parameters.AddRange(parameters);
}
cmd.CommandType = type;
try
{
conn.Open();
object res = cmd.ExecuteScalar();
cmd.Parameters.Clear();
return res;
}
catch (System.Data.SqlClient.SqlException e)
{
conn.Close();
throw e;
}
}
}
}
#endregion
#region ExecuteReader +static void ExecuteReader(string cmdText, Action<SqlDataReader> action, params SqlParameter[] parameters)
/// <summary>
/// 利用委托 执行一个大数据查询的T-SQL语句
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="action">传入执行的委托对象</param>
/// <param name="parameters">参数列表</param>
/// <exception cref="链接数据库异常"></exception>
public static void ExecuteReader(string cmdText, Action<SqlDataReader> action, params SqlParameter[] parameters)
{
ExecuteReader(cmdText, action, CommandType.Text, parameters);
}
#endregion
#region ExecuteReader +static void ExecuteReader(string cmdText, Action<SqlDataReader> action, CommandType type, params SqlParameter[] parameters)
/// <summary>
/// 利用委托 执行一个大数据查询的T-SQL语句
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="action">传入执行的委托对象</param>
/// <param name="type">命令类型</param>
/// <param name="parameters">参数列表</param>
/// <exception cref="链接数据库异常"></exception>
public static void ExecuteReader(string cmdText, Action<SqlDataReader> action, CommandType type, params SqlParameter[] parameters)
{
using (SqlConnection conn = new SqlConnection(connStr))
{
using (SqlCommand cmd = new SqlCommand(cmdText, conn))
{
if (parameters != null)
{
cmd.Parameters.Clear();
cmd.Parameters.AddRange(parameters);
}
cmd.CommandType = type;
try
{
conn.Open();
using (SqlDataReader reader = cmd.ExecuteReader())
{
action(reader);
}
cmd.Parameters.Clear();
}
catch (System.Data.SqlClient.SqlException e)
{
conn.Close();
throw e;
}
}
}
}
#endregion
#region ExecuteReader +static SqlDataReader ExecuteReader(string cmdText, params SqlParameter[] parameters)
/// <summary>
/// 执行一个查询的T-SQL语句, 返回一个SqlDataReader对象, 如果出现SQL语句执行错误, 将会关闭连接通道抛出异常
/// ( 注意：调用该方法后，一定要对SqlDataReader进行Close )
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="parameters">参数列表</param>
/// <exception cref="链接数据库异常"></exception>
/// <returns>SqlDataReader对象</returns>
public static SqlDataReader ExecuteReader(string cmdText, params SqlParameter[] parameters)
{
return ExecuteReader(cmdText, CommandType.Text, parameters);
}
#endregion
#region ExecuteReader +static SqlDataReader ExecuteReader(string cmdText, CommandType type, params SqlParameter[] parameters)
/// <summary>
/// 执行一个查询的T-SQL语句, 返回一个SqlDataReader对象, 如果出现SQL语句执行错误, 将会关闭连接通道抛出异常
/// ( 注意：调用该方法后，一定要对SqlDataReader进行Close )
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="type">命令类型</param>
/// <param name="parameters">参数列表</param>
/// <exception cref="链接数据库异常"></exception>
/// <returns>SqlDataReader对象</returns>
public static SqlDataReader ExecuteReader(string cmdText, CommandType type, params SqlParameter[] parameters)
{
SqlConnection conn = new SqlConnection(connStr);
using (SqlCommand cmd = new SqlCommand(cmdText, conn))
{
if (parameters != null)
{
cmd.Parameters.Clear();
cmd.Parameters.AddRange(parameters);
}
cmd.CommandType = type;
conn.Open();
try
{
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear();
return reader;
}
catch (System.Data.SqlClient.SqlException ex)
{
//出现异常关闭连接并且释放
conn.Close();
throw ex;
}
}
}
#endregion
#region ExecuteDataSet +static DataSet ExecuteDataSet(string cmdText, params SqlParameter[] parameters)
/// <summary>
/// 执行一个查询的T-SQL语句, 返回一个离线数据集DataSet
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="parameters">参数列表</param>
/// <returns>离线数据集DataSet</returns>
public static DataSet ExecuteDataSet(string cmdText, params SqlParameter[] parameters)
{
return ExecuteDataSet(cmdText, CommandType.Text, parameters);
}
#endregion
#region ExecuteDataSet +static DataSet ExecuteDataSet(string cmdText, CommandType type, params SqlParameter[] parameters)
/// <summary>
/// 执行一个查询的T-SQL语句, 返回一个离线数据集DataSet
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="type">命令类型</param>
/// <param name="parameters">参数列表</param>
/// <returns>离线数据集DataSet</returns>
public static DataSet ExecuteDataSet(string cmdText, CommandType type, params SqlParameter[] parameters)
{
using (SqlDataAdapter adapter = new SqlDataAdapter(cmdText, connStr))
{
using (DataSet ds = new DataSet())
{
if (parameters != null)
{
adapter.SelectCommand.Parameters.Clear();
adapter.SelectCommand.Parameters.AddRange(parameters);
}
adapter.SelectCommand.CommandType = type;
adapter.Fill(ds);
adapter.SelectCommand.Parameters.Clear();
return ds;
}
}
}
#endregion
#region ExecuteDataTable +static DataTable ExecuteDataTable(string cmdText, params SqlParameter[] parameters)
/// <summary>
/// 执行一个数据表查询的T-SQL语句, 返回一个DataTable
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="parameters">参数列表</param>
/// <returns>查询到的数据表</returns>
public static DataTable ExecuteDataTable(string cmdText, params SqlParameter[] parameters)
{
return ExecuteDataTable(cmdText, CommandType.Text, parameters);
}
#endregion
#region ExecuteDataTable +static DataTable ExecuteDataTable(string cmdText, CommandType type, params SqlParameter[] parameters)
/// <summary>
/// 执行一个数据表查询的T-SQL语句, 返回一个DataTable
/// </summary>
/// <param name="cmdText">要执行的T-SQL语句</param>
/// <param name="type">命令类型</param>
/// <param name="parameters">参数列表</param>
/// <returns>查询到的数据表</returns>
public static DataTable ExecuteDataTable(string cmdText, CommandType type, params SqlParameter[] parameters)
{
return ExecuteDataSet(cmdText, type, parameters).Tables[0];
}
#endregion
#endregion
}
}
=====================================================
DAL调用
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using Itcast.Mall.Model;
using Itcast.Mall.Utility;
namespace DAL
{
public partial class BookDAO
{
#region 向数据库中添加一条记录 +int Insert(Book model)
///
/// 向数据库中添加一条记录
///
/// 要添加的实体
///
public int Insert(Book model)
{
#region SQL语句
const string sql = @"
INSERT INTO
,
,
,
,
,
,
,
,
,
,
,
)
VALUES (
@CategoryId
,@Title
,@Author
,@PublisherId
,@PublishDate
,@ISBN
,@WordsCount
,@UnitPrice
,@ContentDescription
,@AurhorDescription
,@EditorComment
,@TOC
);select @@IDENTITY";
#endregion
var res = SqlHelper.ExecuteScalar(sql,
new SqlParameter("@CategoryId", model.CategoryId),
new SqlParameter("@Title", model.Title),
new SqlParameter("@Author", model.Author),
new SqlParameter("@PublisherId", model.PublisherId),
new SqlParameter("@PublishDate", model.PublishDate),
new SqlParameter("@ISBN", model.ISBN),
new SqlParameter("@WordsCount", model.WordsCount),
new SqlParameter("@UnitPrice", model.UnitPrice),
new SqlParameter("@ContentDescription", model.ContentDescription),
new SqlParameter("@AurhorDescription", model.AurhorDescription),
new SqlParameter("@EditorComment", model.EditorComment),
new SqlParameter("@TOC", model.TOC)
);
return res == null ? 0 : Convert.ToInt32(res);
}
#endregion
#region 删除一条记录 +int Delete(int id)
public int Delete(int id)
{
const string sql = "DELETE FROM [dbo].[Book] WHERE [Id] = @Id";
return SqlHelper.ExecuteNonQuery(sql, new SqlParameter("@Id", id));
}
#endregion
#region 根据主键ID更新一条记录 +int Update(Book model)
/// <summary>
/// 根据主键ID更新一条记录
/// </summary>
/// <param name="model">更新后的实体</param>
/// <returns>执行结果受影响行数</returns>
public int Update(Book model)
{
#region SQL语句
const string sql = @"
UPDATE
SET
,
,
,
,
,
,
,
,
,
,
,
WHERE [Id] = @Id";
#endregion
return SqlHelper.ExecuteNonQuery(sql,
new SqlParameter("@Id", model.Id),
new SqlParameter("@CategoryId", model.CategoryId),
new SqlParameter("@Title", model.Title),
new SqlParameter("@Author", model.Author),
new SqlParameter("@PublisherId", model.PublisherId),
new SqlParameter("@PublishDate", model.PublishDate),
new SqlParameter("@ISBN", model.ISBN),
new SqlParameter("@WordsCount", model.WordsCount),
new SqlParameter("@UnitPrice", model.UnitPrice),
new SqlParameter("@ContentDescription", model.ContentDescription),
new SqlParameter("@AurhorDescription", model.AurhorDescription),
new SqlParameter("@EditorComment", model.EditorComment),
new SqlParameter("@TOC", model.TOC)
);
}
#endregion
#region 分页查询一个集合 +IEnumerable<Book> QueryList(int index, int size, object wheres, string orderField, bool isDesc = true)
/// <summary>
/// 分页查询一个集合
/// </summary>
/// <param name="index">页码</param>
/// <param name="size">页大小</param>
/// <param name="wheres">条件匿名类</param>
/// <param name="orderField">排序字段</param>
/// <param name="isDesc">是否降序排序</param>
/// <returns>实体集合</returns>
public IEnumerable<Book> QueryList(int index, int size, object wheres, string orderField, bool isDesc = true)
{
var parameters = new List<SqlParameter>();
var whereBuilder = new System.Text.StringBuilder();
if (wheres != null)
{
var props = wheres.GetType().GetProperties();
foreach (var prop in props)
{
if (prop.Name.Equals("__o", StringComparison.InvariantCultureIgnoreCase))
{
// 操作符
whereBuilder.AppendFormat(" {0} ", prop.GetValue(wheres, null).ToString());
}
else
{
var val = prop.GetValue(wheres, null).ToString();
whereBuilder.AppendFormat(" [{0}] = @{0} ", prop.Name);
parameters.Add(new SqlParameter("@" + prop.Name, val));
}
}
}
var sql = SqlHelper.GenerateQuerySql("Book", new[] { "Id", "CategoryId", "Title", "Author", "PublisherId", "PublishDate", "ISBN", "WordsCount", "UnitPrice", "ContentDescription", "AurhorDescription", "EditorComment", "TOC" }, index, size, whereBuilder.ToString(), orderField, isDesc);
using (var reader = SqlHelper.ExecuteReader(sql, parameters.ToArray()))
{
if (reader.HasRows)
{
while (reader.Read())
{
yield return SqlHelper.MapEntity<Book>(reader);
}
}
}
}
#endregion
#region 查询单个模型实体 +Book QuerySingle(object wheres)
/// <summary>
/// 查询单个模型实体
/// </summary>
/// <param name="wheres">条件匿名类</param>
/// <returns>实体</returns>
public Book QuerySingle(object wheres)
{
var list = QueryList(1, 1, wheres, null);
return list != null && list.Any() ? list.FirstOrDefault() : null;
}
#endregion
#region 查询单个模型实体 +Book QuerySingle(int id)
/// <summary>
/// 查询单个模型实体
/// </summary>
/// <param name="id">key</param>
/// <returns>实体</returns>
public Book QuerySingle(int id)
{
const string sql = "SELECT TOP 1 [Id], [CategoryId], [Title], [Author], [PublisherId], [PublishDate], [ISBN], [WordsCount], [UnitPrice], [ContentDescription], [AurhorDescription], [EditorComment], [TOC] FROM [dbo].[Book] WHERE [Id] = @Id";
using (var reader = SqlHelper.ExecuteReader(sql, new SqlParameter("@Id", id)))
{
if (reader.HasRows)
{
reader.Read();
return SqlHelper.MapEntity<Book>(reader);
}
else
{
return null;
}
}
}
#endregion
#region 查询条数 +int QueryCount(object wheres)
/// <summary>
/// 查询条数
/// </summary>
/// <param name="wheres">查询条件
/// new { CategoryId = cat } =》 where category = @category and
/// </param>
/// <returns>条数</returns>
public int QueryCount(object wheres)
{
// 定义参数列表和
var parameters = new List<SqlParameter>();
var whereBuilder = new System.Text.StringBuilder();
if (wheres != null)
{
// 如果传递了where条件 如果传递了where 条件
var props = wheres.GetType().GetProperties();
foreach (var prop in props)
{
if (prop.Name.Equals("__o", StringComparison.InvariantCultureIgnoreCase))
{
// 操作符
whereBuilder.AppendFormat(" {0} ", prop.GetValue(wheres, null).ToString());
}
else
{
// 当前是一个条件
var val = prop.GetValue(wheres, null).ToString();
whereBuilder.AppendFormat(" [{0}] = @{0} ", prop.Name);
parameters.Add(new SqlParameter("@" + prop.Name, val));
}
}
}
var sql = SqlHelper.GenerateQuerySql("Book", new[] { "COUNT(1)" }, whereBuilder.ToString(), string.Empty);
var res = SqlHelper.ExecuteScalar(sql, parameters.ToArray());
return res == null ? 0 : Convert.ToInt32(res);
}
#endregion
}
}
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