PostgreSQL：42883 运算符不存在：没有时区的时间戳 = 文本
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PostgreSQL: 42883 Operator does not exist: timestamp without time zone = text
提问by AndreFeijo
I am using Npgsql 3.0.3.0 and PetaPoco latest version.
我正在使用 Npgsql 3.0.3.0 和 PetaPoco 最新版本。
When I run this command:
当我运行此命令时：
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:
我收到以下错误：
Npgsql.NpgsqlException 42883: operator does not exist: timestamp without time zone = text
Npgsql.NpgsqlException 42883：运算符不存在：没有时区的时间戳 = 文本
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 expectingthe following SQL statement to be built:
我知道错误消息是说我正在尝试将时间戳（日期）与文本进行比较，但是对我来说，比较它们是完全有效的，因为我期望构建以下 SQL 语句：
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.
出于性能原因，我真的不想将我的数据库列类型转换为文本。
采纳答案by Roman Tkachuk
You need to cast value to timestsamp:
您需要将值转换为时间戳：
var sql = new Sql("WHERE date_created = @0::timestamp", dateCreated.ToString("yyyy-MM-dd HH:00:00"));
回答by Shay Rojansky
As @roman-tkachuk answered, you can tell PostgreSQL to cast your string into a timestamp.
正如@roman-tkachuk 回答的那样，您可以告诉 PostgreSQL 将您的字符串转换为时间戳。
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 dateCreateddirectly, without the ToString().
或者更好的是，您可以直接向 PostgreSQL 发送时间戳，而不是发送时间戳的字符串表示并进行转换。为此，只需dateCreated直接发送，无需ToString().
回答by Rajesh Jaiswal
You need to explicit typecast text to timestamp.
您需要将文本显式转换为时间戳。
Try using :
尝试使用：
TO_TIMESTAMP(date_string,'YYYY-MM-DD')
