什么是SQL等效于LINQ .All()

Question

这在SQL中会是什么样子(SQL Server,如果你想特别的话)？

// where people is a list of Person objects with property Name
bool bobs = people.All(p => p.Name == "Bob");

Answer 1

您将检查是否有任何记录与条件不符:

not exists(select * from Persons where not Name = 'Bob')

由于nullC#和SQL之间的比较规则不同,如果字段允许,则需要空值的条件:

not exists(select * from Persons where Name <> 'Bob' or Name is null)