Question

I made an integer 缩略语

ERROR: invalid input syntax for integer: ""

页: 1 页: 1

我正在利用 Java向数据库发出询问。

Answer 1

分类栏可作废,但<代码>>为空示,不得作废。无损分类法(或任何其他类型)为<代码>null。

Answer 2

Double quotes can be used to delimit identifiers, like "myColumnName".
Single quotes are used to delimit values in string literals, like my string literal .
For integer values you typically use numeric constants to input values, which are not quoted at all, like 123. (But you can cast a string literal, too.)
Numeric data types (integer, numeric, double precision, ...) cannot store empty strings ( ), only string types (text, varchar, ...) can.
To pass a null value, use the key word null. Or omit the column completely from your INSERT statement. If you did not define a different column default, it defaults to null automatically.

你在错误信息中看到的双重说法只是Pogres为错误信息添加的限定词,意思是你通过了一个空洞()。如果你实际上已经过,

“”

(这要求单独引用:<>>>),你将看到这一错误信息:

ERROR:  invalid input syntax for integer: """"

不清楚 Java是如何发挥作用的。

审议以下章节:Lexical Structure。

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