在h2数据库上运行select查询时遇到问题

Question

我正在H2数据库上运行示例查询，如下所述 -

select count(*) from Employee where employee_name is not null;

但问题是H2不支持is not null，请建议可以替代的方法。

Answer 1

试试这个

select count(*) from Employee 

WHERE employee_name = ? or (employee_name is null and ? is null);

表达式employee_name IS NULL如果变量employee_name的值为NULL，则返回TRUE， 否则返回FALSE。