public class MicroDataTable
{ /// <summary>
/// 整个查询语句结果的总条数，而非本DataTable的条数
/// </summary>
public int TotalCount { get; set; }
public List<MicroDataColumn> Columns { get; set; } = new List<MicroDataColumn>();
public List<MicroDataRow> Rows { get; set; } = new List<MicroDataRow>();
public MicroDataColumn[] PrimaryKey { get; set; }
public MicroDataRow NewRow()
{
return new MicroDataRow(this.Columns, new object[Columns.Count]);
}
}
public class MicroDataColumn
{
public string ColumnName { get; set; }
public Type ColumnType { get; set; }
}
public class MicroDataRow
{
private object[] _ItemArray;
public List<MicroDataColumn> Columns { get; private set; }
public MicroDataRow(List<MicroDataColumn> columns, object[] itemArray)
{
this.Columns = columns;
this._ItemArray = itemArray;
}
public object this[int index]
{
get { return _ItemArray[index]; }
set { _ItemArray[index] = value; }
}
public object this[string columnName]
{
get
{
int i = 0;
foreach (MicroDataColumn column in Columns)
{
if (column.ColumnName == columnName)
break;
i++;
}
return _ItemArray[i];
}
set
{
int i = 0;
foreach (MicroDataColumn column in Columns)
{
if (column.ColumnName == columnName)
break;
i++;
}
_ItemArray[i] = value;
}
}
}

public static MicroDataTable ExecuteDataTable(this DbContext context, string sql, params object[] parameters)
{
var concurrencyDetector = context.Database.GetService<IConcurrencyDetector>();
using (concurrencyDetector.EnterCriticalSection())
{
var rawSqlCommand = context.Database.GetService<IRawSqlCommandBuilder>().Build(sql, parameters);
RelationalDataReader query = rawSqlCommand.RelationalCommand.ExecuteReader(context.Database.GetService<IRelationalConnection>(), parameterValues: rawSqlCommand.ParameterValues);
return MicroDataTableHelper.FillDataTable(query.DbDataReader, 0, int.MaxValue);
}
}
public static MicroDataTable ExecuteDataTable(this DbContext context, string sql, int pageIndex, int pageSize, params object[] parameters)
{
var concurrencyDetector = context.Database.GetService<IConcurrencyDetector>();
using (concurrencyDetector.EnterCriticalSection())
{
var rawSqlCommand = context.Database.GetService<IRawSqlCommandBuilder>().Build(sql, parameters);
RelationalDataReader query = rawSqlCommand.RelationalCommand.ExecuteReader(context.Database.GetService<IRelationalConnection>(), parameterValues: rawSqlCommand.ParameterValues);
return MicroDataTableHelper.FillDataTable(query.DbDataReader, 0, int.MaxValue);
}
}

public static MicroDataTable FillDataTable(DbDataReader reader, int pageIndex, int pageSize)
{
bool defined = false;
MicroDataTable table = new MicroDataTable();
int index = 0;
int beginIndex = pageSize * pageIndex;
int endIndex = pageSize * (pageIndex + 1) - 1;
while (reader.Read())
{
object[] values = new object[reader.FieldCount];
if (!defined)
{
for (int i = 0; i < reader.FieldCount; i++)
{
MicroDataColumn column = new MicroDataColumn()
{
ColumnName = reader.GetName(i),
ColumnType = reader.GetFieldType(i)
};
table.Columns.Add(column);
}
defined = true;
}
if (index >= beginIndex && index <= endIndex)
{
reader.GetValues(values);
table.Rows.Add(new MicroDataRow(table.Columns, values));
}
index++;
}
table.TotalCount = index;
return table;
}

using (IDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection))
{
int fieldCount = reader.FieldCount;
for (int i = 0; i < fieldCount; i++)
{
table.Columns.Add(reader.GetName(i), reader.GetFieldType(i));
}
object[] values = new object[fieldCount];
int currentIndex = 0;
int startIndex = pageSize * pageIndex;
try
{
table.BeginLoadData();
while (reader.Read())
{
if (startIndex > currentIndex++)
continue;
if (pageSize > 0 && (currentIndex - startIndex) > pageSize)
break;
reader.GetValues(values);
table.LoadDataRow(values, true);
}
}
finally
{
table.EndLoadData();
try //lgy:由于连接阿里云ADS数据库cmd.Cancel()会报错，所以把错误忽略了。
{
cmd.Cancel();
}
catch 
{ 
}
reader.Close();
}
}