精简的后台程序代码——Select

public class Select

{

#region Class Members

private static string SELECT_PAGE_SQL = "SELECT TOP {0} * FROM ( SELECT ROW_NUMBER() OVER ({1}) AS ROW , {2} FROM {3} WHERE {4} ) AS DATALIST WHERE ROW > {5}";

private static string SELECT_SQL = @"SELECT {0} FROM {1} WHERE {2}";

/// <summary>

/// 数据操作类

/// </summary>

private DbHelper _DbHelper;

/// <summary>

/// 表名

/// </summary>

private string _TableName;

/// <summary>

/// 列名称/值 的集合

/// </summary>

private string _Columns = " * ";

private string _From;

private string _Where;

private string _OrderBy;

private object _Parameter;

private DynamicParameters _Parameters = new DynamicParameters();

/// <summary>

/// 页码

/// </summary>

private int _Page;

/// <summary>

/// 每页条数

/// </summary>

private int _Rows;

#endregion

#region Constructors

public Select(DbHelper dbHelper, string tableName, string colums)

{

_DbHelper = dbHelper;

_TableName = tableName;

_Columns = colums;

}

#endregion

#region Methods

public Select From(string from)

{

_From = from;

return this;

}

public Select Where(string where)

{

_Where = where;

return this;

}

public Select OrderBy(string orderBy)

{

_OrderBy = orderBy;

return this;

}

public Select Parameter(object parameter)

{

_Parameter = parameter;

return this;

}

/// <summary>

/// 条件中的参数

/// </summary>

/// <param name="parameters"></param>

/// <returns></returns>

public Select Parameters(params object[] parameters)

{

if (parameters != null)

{

for (var i = 0; i < parameters.Length; i++)

{

_Parameters.Add("@" + i, parameters[i]==null?0: parameters[i]);

}

}

return this;

}

public Select Paging(int page, int rows)

{

_Page = page;

_Rows = rows;

return this;

}

public IEnumerable<T> Query<T>()

{

var sql = string.Empty;

// 分页

if (_Rows > 0 && _Page > 0)

{

if (string.IsNullOrEmpty(_From))

_From = _TableName;

if (string.IsNullOrEmpty(_Where))

_Where = " 1=1 ";

if (!string.IsNullOrEmpty(_OrderBy))

_Where += " Order By" + _OrderBy;

// 分页

sql = string.Format(SELECT_PAGE_SQL, _Rows, _OrderBy, _Columns, _From, _Where, (_Page - 1) * _Rows);

}

else

{

if (string.IsNullOrEmpty(_From))

_From = _TableName;

if (string.IsNullOrEmpty(_Where))

_Where = " 1=1 ";

if (!string.IsNullOrEmpty(_OrderBy))

_Where += " Order By" + _OrderBy;

sql = string.Format(SELECT_SQL, _Columns, _From, _Where);

}

return _DbHelper.Query<T>(sql, _Parameter == null ? _Parameters : _Parameter);

}

#endregion

}

public class Select_T<T>

{

#region Class Members

private static string SELECT_PAGE_SQL = "SELECT TOP {0} * FROM ( SELECT ROW_NUMBER() OVER (Order By {1}) AS ROW , {2} FROM {3} WHERE {4} ) AS DATALIST WHERE ROW > {5}";

private static string SELECT_SQL = @"SELECT {0} FROM {1} WHERE {2}";

/// <summary>

/// 数据操作类

/// </summary>

private DbHelper _DbHelper;

/// <summary>

/// 表名

/// </summary>

private string _TableName;

/// <summary>

/// 列名称/值 的集合

/// </summary>

private string _Columns = " * ";

private string _Where;

private string _OrderBy;

private string _From;

private object _Parameter;

private DynamicParameters _Parameters = new DynamicParameters();

/// <summary>

/// 页码

/// </summary>

private int _Page;

/// <summary>

/// 每页条数

/// </summary>

private int _Rows;

#endregion

#region Constructors

public Select_T(DbHelper dbHelper, string tableName, string colums)

{

_DbHelper = dbHelper;

_TableName = tableName;

_Columns = colums;

}

#endregion

#region Methods

public Select_T<T> Where(string where)

{

_Where = where;

return this;

}

public Select_T<T> OrderBy(string orderBy)

{

_OrderBy = orderBy;

return this;

}

public Select_T<T> From(string from)

{

_From = from;

return this;

}

public Select_T<T> Page(int page, int rows)

{

_Page = page;

_Rows = rows;

return this;

}

/// <summary>

/// 条件中的参数

/// </summary>

/// <param name="parameters"></param>

/// <returns></returns>

public Select_T<T> Parameters(params object[] parameters)

{

if (parameters != null)

{

for (var i = 0; i < parameters.Length; i++)

{

_Parameters.Add("@" + i, parameters[i]==null?0: parameters[i]);

}

}

return this;

}

/// <summary>

/// 初始化参数集合

/// </summary>

/// <param name="parameters">所需参数集合</param>

/// <returns></returns>

public Select_T<T> Parameter(object parameter)

{

_Parameter = parameter;

return this;

}

public IEnumerable<T> Query()

{

var sql = string.Empty;

// 分页

if (_Rows > 0 && _Page > 0)

{

if (string.IsNullOrEmpty(_From))

_From = _TableName;

if (string.IsNullOrEmpty(_Where))

_Where = " 1=1 ";

if (string.IsNullOrEmpty(_OrderBy))

_OrderBy="ID DESC";

// 分页

sql = string.Format(SELECT_PAGE_SQL, _Rows, _OrderBy, _Columns, _From, _Where, (_Page - 1) * _Rows);

}

else

{

if (string.IsNullOrEmpty(_From))

_From = _TableName;

if (string.IsNullOrEmpty(_Where))

_Where = " 1=1 ";

if (!string.IsNullOrEmpty(_OrderBy))

_Where += " Order By " + _OrderBy;

sql = string.Format(SELECT_SQL, _Columns, _From, _Where);

}

return _DbHelper.Query<T>(sql, _Parameter == null ? _Parameters : _Parameter);

}

#endregion

}