PostgreSQL：选择时间戳为空的地方
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PostgreSQL: Select where timestamp is empty
提问by ReK_
I have a query that looks like the following:
我有一个如下所示的查询：
SELECT * FROM table WHERE timestamp = NULL;
SELECT * FROM table WHERE timestamp = NULL;
The timestamp column is a timestamp with time zone data type (second type in thistable). This is in PostgreSQL 8.4.
时间戳列是具有时区数据类型（此表中的第二种类型）的时间戳。这是在 PostgreSQL 8.4 中。
What I'm trying to accomplish is to only select rows that have not had a timestamp inserted. When I look at the data in pgAdmin the field is empty and shows no value. I've tried where timestamp = NULL, 'EPOCH'(which you would think would be the default value), a valid timestamp of zeros (0000-00-00 00:00:00-00, which results in a out of range error), the lowest date possible according to the docs (January 1, 4713 BC) and a blank string ('', which just gets a data type mismatch error). There also appears to be no is_timestamp()function that I can use to check if the result is not a valid timestamp.
我想要完成的是只选择没有插入时间戳的行。当我查看 pgAdmin 中的数据时，该字段为空且不显示任何值。我试过 where timestamp = NULL, 'EPOCH'（你会认为这是默认值），一个有效的零时间戳（0000-00-00 00:00:00-00，这会导致超出范围的错误），根据文档可能的最低日期（January 1, 4713 BC）和一个空白string ( ''，它只是得到一个数据类型不匹配错误)。似乎也没有is_timestamp()可用于检查结果是否为有效时间戳的函数。
So, the question is, what value is in that empty field that I can check for?
所以，问题是，我可以检查的空字段中的值是什么？
Thanks.
谢谢。
EDIT: The field does not have a default value.
编辑：该字段没有默认值。
回答by XMen
Try timestamp is nullas i use this syntax in MySQL
尝试timestamp is null在 MySQL 中使用此语法
