迁移房间数据库时无法添加索引

Question

我正在将房间数据库版本从 1 迁移到版本 2。迁移时，我在迁移代码中添加了索引，但它不起作用。

下面是代码：

static final Migration MIGRATION_1_2 = new Migration(1, 2) {
        @Override
        public void migrate(SupportSQLiteDatabase database) {

             database.execSQL("CREATE TABLE student (" +
                    "student_id INTEGER PRIMARY KEY NOT NULL ," +
                    "student_name TEXT," +
                    "student_roll_no TEXT," +
                    "department_id INTEGER, FOREIGN KEY (department_id) REFERENCES department(dept_id)" +
                    ")");
            database.execSQL("CREATE INDEX `index_student_department_id` ON `student` (`department_id`)");


        }
    };

这导致：-

Expected indices=[Index{name='index_student_department_id', unique=false, columns=[department_id]}]
Result Found:indices=null

Answer 1

为 Student 表创建实体，使其具有创建索引的索引。消息说预期但 indices 但什么也没找到。

喜欢

@Entity(indices = {@Index(name="`index_student_department_id`", unique = false, value =  {"`department_id`"})})
public class Student {
    .......
}

或（unique = false 是默认值）

@Entity(indices = {@Index(name="`index_student_department_id`", value =  {"`department_id`"})})
public class Student {
    .......
}