比如：
SELECT * FROM tb_school WHERE id=(SELECT MAX(id) FROM tb_school WHERE status =1)
上面語句屬于一般復雜語句，可以在generator生成的代碼上擴展，擴展方式，我記錄在后面，對于比這還要復雜的，還是得手寫。
擴展參考http://www.mybatis.org/generator/generatedobjects/extendingExampleClass.html
擴展的方式就是繼承自動生成的Example class，然后使用它
public class Max_schoolExample extends Tb_schoolExample {
public static class ExtendedCriteria extends Tb_schoolExample.Criteria {
public Criteria andMaxStatusEquals() {
StringBuffer sb = new StringBuffer("id=(SELECT MAX(id) FROM tb_school WHERE status =1)");
addCriterion(sb.toString());
return this;
}
}
public ExtendedCriteria createExtendedCriteria() {
ExtendedCriteria criteria = new ExtendedCriteria();
if (oredCriteria.size() == 0) {
oredCriteria.add(criteria);
}
return criteria;
}
}