mybatis if list

In MyBatis, you can use `<if>` tags to conditionally include or exclude parts of your SQL queries. When dealing with a list, you can use the `<foreach>` tag in combination with the `<if>` tag to iterate over the list and conditionally generate SQL statements.

Here's an example of how you can use `<if>` and `<foreach>` tags with a list in MyBatis:

<select id="getUserList" resultType="User">
  SELECT * FROM users
  WHERE 1=1
  <if test="userIds != null and !userIds.isEmpty()">
    AND user_id IN
    <foreach item="userId" collection="userIds" open="(" separator="," close=")">
      #{userId}
    </foreach>
  </if>
</select>

In this example, the SQL query selects all users from the `users` table. If the `userIds` list is not null and not empty, it dynamically adds a condition to filter the results by the `user_id` column using the `IN` operator.

You can pass the `userIds` list as a parameter to your MyBatis mapper method:

List<User> getUserList(List<Integer> userIds);

By doing so, MyBatis will handle the iteration and conditional inclusion of the SQL statements based on the values in the `userIds` list.