我正在使用C#(Npgsql 3.2.4.1)和PostgreSQL(9.6.5)以及pgAdmin 3。
我的表在PostgreSQL中:
create table Data
(
idref integer NOT NULL,
val text,
dt timestamp without time zone NOT NULL,
constraint PK_Data_idRef_Dt primary key (idRef, Dt),
constraint FK_Data_Ref foreign key(idRef) references Ref(Id)
);
当我运行函数(C#)时:
static void Main(string[] args)
{
var connString = "Server = 0.0.0.0; Port = 5432; Userid = user; Password = password; CommandTimeout=300; Timeout = 300; Database = database";
using (var conn = new NpgsqlConnection(connString))
{
NpgsqlCommand cmd = new NpgsqlCommand(@"select Val, Dt from Data where idRef = @Id and Dt >= @Dt and Dt <= @Dt order by Dt asc;", conn);
NpgsqlParameter parameterId = new NpgsqlParameter("Id", NpgsqlDbType.Integer);
parameterId.Value = 4;
cmd.Parameters.Add(parameterId);
NpgsqlParameter parameterDtBegin = new NpgsqlParameter("DtBegin", NpgsqlDbType.Timestamp);
parameterDtBegin.Value = new DateTime(2017, 9, 1, 0,0,0);
cmd.Parameters.Add(parameterDtBegin);
NpgsqlParameter parameterDtEnd = new NpgsqlParameter("DtEnd", NpgsqlDbType.Timestamp);
parameterDtEnd.Value = new DateTime(2017, 10, 1, 0, 0, 0);
cmd.Parameters.Add(parameterDtEnd);
conn.Open();
using (var reader = cmd.ExecuteReader())
while (reader.Read())
Console.WriteLine(reader.GetString(0));
}
Console.ReadKey();
}
我收到以下错误:{42883: operator does not exist: @ timestamp without time zone} System.Exception {Npgsql.PostgresException}
。我看过文章(link),但这个想法对我有用。
谢谢你的回答!
答案 0 :(得分:1)
NpgsqlCommand cmd = new NpgsqlCommand(@"select Val, Dt from Data where idRef = :id and Dt >= :date and Dt <= :date2 order by Dt asc;", conn);
cmd.Parameters.Add(":id", NpgsqlDbType.Integer).Value = 3;
cmd.Parameters.Add(":date", NpgsqlDbType.Timestamp).Value = new DateTime(2017, 9, 1, 0, 0, 0);
cmd.Parameters.Add(":date2", NpgsqlDbType.Timestamp).Value = new DateTime(2017, 10, 7, 0, 0, 0);
conn.Open();
using (var reader = cmd.ExecuteReader())
while (reader.Read())
Console.WriteLine(reader.GetString(0));