/// <summary>
/// 失败返回null
/// </summary>
public override T Select <T>(SelectBuilder selectBuilder)
{
if (selectBuilder == null)
{
throw new NotImplementedException("缺少有效的" + nameof(SelectBuilder));
}
T result = new T();
DbCommand command = Session.CreateCommand();
command.CommandText = selectBuilder.ToQueryString(Session, new T().TableName);
selectBuilder.AddParameter(command, Session);
WriteQueryLog(command, Session);
using (var reader = Session.ExecuteDataReader(command))
{
if (reader.Read())
{
var fields = selectBuilder.ComponentSelect.GetSelectFields();
if (fields.Count() == 0)
{
result.Init(reader);
}
else
{
result.Init(reader, fields);
}
return(result);
}
else
{
return(null);
}
}
}
/// <summary>
/// 未查询到数据时返回 null
/// </summary>
public override DbDataReader SelectAsDataReader <T>(SelectBuilder selectBuilder)
{
if (selectBuilder == null)
{
throw new NotImplementedException("缺少有效的" + nameof(SelectBuilder));
}
DbCommand command = Session.CreateCommand();
command.CommandText = selectBuilder.ToQueryString(Session, new T().TableName);
selectBuilder.AddParameter(command, Session);
WriteQueryLog(command, Session);
return(Session.ExecuteReader(command));
}
/// <summary>
/// 未查询到数据时返回 null
/// </summary>
public override List <string> SelectAsStrings <T>(SelectBuilder selectBuilder)
{
if (selectBuilder == null)
{
throw new NotImplementedException("缺少有效的" + nameof(SelectBuilder));
}
DbCommand command = Session.CreateCommand();
command.CommandText = selectBuilder.ToQueryString(Session, new T().TableName);
selectBuilder.AddParameter(command, Session);
WriteQueryLog(command, Session);
var reader = Session.ExecuteReader(command);
List <string> result = new List <string>();
var field = selectBuilder.ComponentSelect.GetSelectFields().First();
while (reader.Read())
{
result.Add(reader[field] as string);
}
return(result);
}
/// <summary>
/// 未查询到数据时返回 null
/// </summary>
public override string SelectAsString <T>(SelectBuilder selectBuilder)
{
if (selectBuilder == null)
{
throw new NotImplementedException("缺少有效的" + nameof(SelectBuilder));
}
DbCommand command = Session.CreateCommand();
command.CommandText = selectBuilder.ToQueryString(Session, new T().TableName);
selectBuilder.AddParameter(command, Session);
WriteQueryLog(command, Session);
var data = Session.ExecuteScalar(command);
if (data != null)
{
return(data.ToString());
}
else
{
return(null);
}
}