Mybatis动态SQL拼接

1. <!—需求1：
2. 根据作者名字和博客名字来查询博客！
3. 如果作者名字为空，那么只根据博客名字查询，反之，则根据作者名来查询
4. select * from blog where title = #{title} and author = #{author}
5. —>
7. select * from blog where
9. title = #{title}
12. and author = #{author}

14. 
    select * from blog title = #{title} and author = #{author}

17. update blog
20. title = #{title},
23. author = #{author}
26. where id = #{id};

2. select * from blog
6. title = #{title}
9. and author = #{author}
12. and views = #{views}
16. 
    
18. select * from blog
20. <!—
21. collection:指定输入对象中的集合属性
22. item:每次遍历生成的对象
23. open:开始遍历时的拼接字符串
24. close:结束时拼接的字符串
25. separator:遍历对象之间需要拼接的字符串
26. select * from blog where 1=1 and (id=1 or id=2 or id=3)
27. —>
29. id=#{id}

title = #{title} and author = #{author}

select * from blog