How to use FirstOrDefault for two primary keys

Question

有两个主键a和b一个键可以编译两个键怎么样

var product = db.TMP_HELLO.FirstOrDefault<TMP_HELLO>(instrmnt => (instrmnt.a == good.a; instrmnt.b == good.b));

Answer 1

Use the && operator in your lambda.

var product = db.TMP_HELLO
        .FirstOrDefault<TMP_HELLO>(
            instrmnt => instrmnt.a == good.a && instrmnt.b == good.b);