sql - If-exists-UPDATE-else-INSERT 与 Linq-to-Entities？

Question

有没有办法使用实体和 LinQ 编写相同的 SQL 原子指令？

IF EXISTS (SELECT * FROM MyTable WHERE ID = @Id) UPDATE MyTable SET name = @name ELSE INSERT INTO MyTable (@Id, @name)

还是您需要从 EF 中调用存储过程？

Answer 1

The Entity Framework keeps track of the lifespan of objects:

• If the object was initialized from a query, the framework understands a record should exist in the database and will perform an UPDATE when pushing changes back to the database.
• If the object was initialized in code, the framework understands it as a "new" object and performs an INSERT when pushing the changes to the database.

If you wish to have a single piece of SQL called, regardless of whether an INSERT or UPDATE operation is required, you will have to specify a stored procedure.