英文:
Postgres prepared statement bind `now()`
问题
我有一个准备好的插入语句，其中有一个用于日期的占位符。我希望能够插入用户提供的日期，或者如果未提供日期，则回退到使用 now() 插入当前时间。是否可以绑定 now() 的结果，还是我需要使用第二个插入语句直接在语句中使用 now() 而不是占位符？
例如，我可以这样做：
PREPARE my_statement AS
INSERT INTO my_table (date_column)
VALUES ($1);
EXECUTE my_statement (now());
还是我需要这样做：
PREPARE my_statement AS
INSERT INTO my_table (date_column)
VALUES (now);
EXECUTE my_statement;
英文:
I have a prepared insert statement which has a placeholder for a date. I want to be able to insert a date provided by a user, or if it has not been provided fall back to inserting the current time using now(). Is it possible to bind the result of now() or do I need to use a second insert statement using now() directly in the statement rather than a placeholder?
For example, can I do this:
PREPARE my_statement AS
INSERT INTO my_table (date_column)
VALUES ($1);
EXECUTE my_statement (now());
or do I need to do this
PREPARE my_statement AS
INSERT INTO my_table (date_column)
VALUES (now);
EXECUTE my_statement;
答案1
得分: 1
是的。根据EXECUTE语句的文档，每个参数“必须是产生与该参数的数据类型兼容的值的表达式”。这允许使用任意表达式，如now()函数调用，而不仅仅是文字值。
英文:
> Is it possible to bind the result of now()?
Yes. According to the docs of the EXECUTE statement, each of the parameters "must be an expression yielding a value that is compatible with the data type of this parameter". This allows arbitrary expressions, such as the now() function call, not just literal values.
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