PostgreSQL: 42883 Operator does not exist: timestamp without time zone = text

问题

I am using Npgsql 3.0.3.0 and PetaPoco latest version.

When I run this command:

var dateCreated = DateTime.Now; // just an example
var sql = new Sql("WHERE date_created = @0", dateCreated.ToString("yyyy-MM-dd HH:00:00"));
var category = db.SingleOrDefault<Category>(sql);

I get the following error:

Npgsql.NpgsqlException 42883: operator does not exist: timestamp without time zone = text

I understand the error message is saying I'm trying to compare a timestamp (date) with a text, however for me it's perfectly valid to compare them as I am expecting the following SQL statement to be built:

SELECT * FROM category WHERE date_created = '2017-02-03 15:00:00'

I don't really want to typecast my database column to text for performance reasons.

回答1:

You need to cast value to timestsamp:

var sql = new Sql("WHERE date_created = @0::timestamp", dateCreated.ToString("yyyy-MM-dd HH:00:00"));

回答2:

As @roman-tkachuk answered, you can tell PostgreSQL to cast your string into a timestamp.

Or better yet, you can simply send a timestamp to PostgreSQL directly, rather than sending a string representation of a timestamp and having it cast. To do that, simply send dateCreated directly, without the ToString().

来源：https://stackoverflow.com/questions/42033881/postgresql-42883-operator-does-not-exist-timestamp-without-time-zone-text