Question

为什么我在sqlite

中使用IS NULL时无法调用空数据行

select roomkeyID from roomkey where dateOfReturn is null;

CREATE TABLE ROOMKEY ( 
    roomkeyID VARCHAR(10) not null primary key,
    roomID VARCHAR(10) not null, 
    keyID VARCHAR(10) not null,
    dateOfIssue DATETIME,
    dateOfReturn DATETIME,
    FOREIGN KEY (roomID) REFERENCES ROOM(roomID),
    FOREIGN KEY (keyID ) REFERENCES KEY(keyID )
)

"RK000001","R106","K0003","12/17/2015"," "
"RK000090","R101","K0002","12/12/2015"," "

Answer 1

从示例中可以看出，在dateOfReturn字段中，您没有NULL值，而是内部有空格的字符串。如果是这样，那么您必须将查询更改为：

select roomkeyID from roomkey where dateOfReturn is null or dateOfReturn = ' '

我不能在sqlite中调用null数据行

1 个答案: