Mybatis：Mybatis注解实现动态SQL注意事项

1. 使用<script>声明动态SQL

@Select("<script>" + 
    "select * from User " + 
    "<where>" + 
    " id = #{id}" + 
    "</where>" + 
    "</script>")
User selectUser(int id);

2. 判断空字符用单引号

@Select("<script>" + 
    "select * from User " + 
    "<where>" + 
    "<if test=\"name != null and name != ''\">" + 
    " name = #{name}" + 
    "</if>" + 
    "</where>" + 
    "</script>")
User selectUser(String name);

3. if、when等判断条件拼接用and或or 

@Select("<script>" + 
    "select * from User " + 
    "<where>" + 
    "<if test=\"name != null and name != ''\">" + 
    " name = #{name}" + 
    "</if>" + 
    "</where>" + 
    "</script>")
User selectUser(String name);

4. 模糊查询使用concat()拼接函数

@Select("<script>" + 
    "select * from User " + 
    "<where>" + 
    "<if test=\"name != null and name != ''\">" + 
    " name like concat('%', #{name}, '%') " + 
    "</if>" + 
    "</where>" + 
    "</script>")
User selectUser(String name);