Question

SQL 从字符串向 datetime 转换时失败.

select a.readerNo,readerName,bookName,returnDate
from Reader a,borrow b,Book c
where a.readerNo=b.readerNo and b.bookNo=c.bookNo and b.bookNo in(select b.bookNo from borrow
where returnDate='NULL' and bookNo in(select bookNo from borrow where bookNo='001-000029' ) )

Answer 1

select a.readerNo,readerName,bookName,returnDate
from Reader a,borrow b,Book c
where a.readerNo=b.readerNo and b.bookNo=c.bookNo and b.bookNo in(select b.bookNo from borrow
where returnDate is NULL and bookNo in(select bookNo from borrow where bookNo='001-000029' ) )

追问

语法没错误，可是输不出具体数据

Answer 2

returnDate='NULL'

修改为

returnDate IS NULL