Oracle 列上的 HQL“为空”和“！=空”
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HQL "is null" And "!= null" on an Oracle column
提问by Eric V
Does hibernateconvert column != nullin HQLto a column is nullin SQL?
是否冬眠转换column != null在HQL到column is null在SQL？
回答by Eduard
That is a binary operator in hibernate you should use
那是您应该使用的休眠中的二元运算符
is not null
Have a look at 14.10. Expressions
回答by JB Nizet
No. You have to use is nulland is not nullin HQL.
不，您必须在 HQL 中使用is null和is not null。
回答by Boris Brodski
If you do want to use nullvalues with '='or '<>'operators you may find the
如果您确实想使用null带有'='或'<>'运算符的值，您可能会发现
very useful.
很有用。
Short example for '=': The expression
简短示例'='：表达式
WHERE t.field = :param
you refactor like this
你这样重构
WHERE ((:param is null and t.field is null) or t.field = :param)
Now you can set the parameter parameither to some non-null value or to null:
现在您可以将参数设置param为某个非空值或null：
query.setParameter("param", "Hello World"); // Works
query.setParameter("param", null); // Works also
回答by egallardo
No. See also this link Handle conditional null in HQLfor tips and tricks on how to handle comparisons with both null and non-null values.
否。另请参阅此链接在 HQL 中处理条件空值，了解有关如何处理与空值和非空值进行比较的提示和技巧。
