/// <summary>
/// 查询返回第一行第一列字段的值
/// </summary>
/// <typeparam name="TResult">接受查询结果类型</typeparam>
/// <param name="field">查询的字段</param>
/// <returns></returns>
public TResult ToScalar <TResult>(string field)
{
Fields.Clear();
Fields.Add(field);
string cmdText = ToString();
object result = null;
if (Master)
{
result = PgSqlHelper.ExecuteScalar(CommandType.Text, cmdText, command =>
{
this.Command = command;
this.Connection = command?.Connection;
}, this.ParamList.ToArray());
}
else
{
result = PgSqlHelper.ExecuteScalarSlave(CommandType.Text, cmdText, command =>
{
this.Command = command;
this.Connection = command?.Connection;
}, this.ParamList.ToArray());
}
return((TResult)result);
}
/// <summary>
/// 查询返回第一行第一列字段的值
/// </summary>
/// <typeparam name="TResult">接受查询结果类型</typeparam>
/// <param name="field">查询的字段</param>
/// <returns></returns>
public TResult ToScalar <TResult>(string field)
{
Fields.Clear();
Fields.Add(field);
string cmdText = ToString();
object _val = null;
if (PgSqlHelper.InstanceSlave != null && !this.Master)
{
_val = PgSqlHelper.ExecuteScalarSlave(CommandType.Text, cmdText, this.ParamList.ToArray());
}
else
{
_val = PgSqlHelper.ExecuteScalar(CommandType.Text, cmdText, this.ParamList.ToArray());
}
return((TResult)_val);
}
/// <summary>
/// 查询返回第一行第一列字段的值
/// </summary>
/// <typeparam name="TResult">接受查询结果类型</typeparam>
/// <param name="field">查询的字段</param>
/// <returns></returns>
public TResult ToScalar <TResult>(string field)
{
if (!string.IsNullOrEmpty(GroupByText))
{
throw new ArgumentException("聚合查询不允许使用 GROUP BY 条件！");
}
Fields.Clear();
Fields.Add(field);
string cmdText = ToSQL();
object result = null;
if (Master)
{
result = PgSqlHelper.ExecuteScalar(CommandType.Text, cmdText, command =>
{
this.Command = command;
this.Connection = command?.Connection;
}, this.ParamList.ToArray());
}
else
{
result = PgSqlHelper.ExecuteScalarSlave(CommandType.Text, cmdText, command =>
{
this.Command = command;
this.Connection = command?.Connection;
}, this.ParamList.ToArray());
}
// Clear();
if (result == null)
{
return(default(TResult));
}
else
{
return((TResult)result);
}
}