mybatis @Select if

Sure! In MyBatis, the `@Select` annotation is used to declare a SELECT statement in a mapper interface or XML mapper file. It is used to retrieve data from the database.

Here's an example of how to use `@Select` annotation in MyBatis:

@Mapper
public interface UserMapper {
    @Select("SELECT * FROM users WHERE id = #{id}")
    User getUserById(int id);
}

In this example, the `@Select` annotation is used to define a SELECT statement that retrieves a user from the database based on the given ID.

You can also use dynamic SQL in `@Select` annotation by using MyBatis's expression language. For example:

@Mapper
public interface UserMapper {
    @Select("SELECT * FROM users WHERE 1=1"
            + "<if test='name != null'> AND name = #{name}</if>"
            + "<if test='age != null'> AND age = #{age}</if>")
    List<User> getUsersByNameAndAge(@Param("name") String name, @Param("age") Integer age);
}

In this example, the `@Select` annotation is used with dynamic SQL. The SQL query is constructed based on the provided parameters, and the conditions are only added if the corresponding parameter values are not null.

I hope this answers your question! Let me know if you have any further queries.