需求
最近自己玩发现MyBatisPlus还是挺好用的，但是忽然发现对于一个持久层框架来说支持拼接复杂的SQL也是一个优势，对一个持久层框架拼接SQL来说，or比and更难拼，所以此处用案例来实现MybatisPlus中or和and的简单使用。
代码下载（内含数据库）
ChaiRongD/Demooo - Gitee.com
and和or的使用
案例1：AandB
@GetMapping("/AandB") public Object AandB(){ //SELECT id,name,age,sex FROM student WHERE (name = ? AND age = ?) List<Student> list = studentService.lambdaQuery().eq(Student::getName, "1").eq(Student::getAge, 1).list(); return list; }
案例2：AorB
@GetMapping("/AorB") public Object AorB(){ //SELECT id,name,age,sex FROM student WHERE (name = ? OR age = ?) List<Student> list = studentService.lambdaQuery().eq(Student::getName, "1").or().eq(Student::getAge, 12).list(); return list; }
案例3：A or（C and D)
@GetMapping("/A_or_CandD") public Object A_or_CandD() { //SELECT id,name,age,sex FROM student WHERE (name = ? OR (name = ? AND age = ?)) List<Student> list = studentService .lambdaQuery() .eq(Student::getName, "1") .or(wp -> wp.eq(Student::getName, "1").eq(Student::getAge, 12)) .list(); return list;
案例4：(AandB)or(CandD)
@GetMapping("/AandB_or_CandD") public Object AandB_or_CandD() { // SELECT id,name,age,sex FROM student WHERE ((name = ? AND age = ?) OR (name = ? AND age = ?)) List<Student> list = studentService .lambdaQuery() .and(wp -> wp.eq(Student::getName, "1").eq(Student::getAge, 12)) .or(wp -> wp.eq(Student::getName, "1").eq(Student::getAge, 12)) .list(); return list; }
案例5：A or (B and ( C or D))
@GetMapping("/complex") public Object complex() { // SELECT * FROM student WHERE ((name <> 1) OR (name = 1 AND (age IS NULL OR age >= 11))) List<Student> list = studentService .lambdaQuery() .and(wp -> wp.ne(Student::getName, "1")) .or( wp -> wp.eq(Student::getName, "1") .and(wpp -> wpp.isNull(Student::getAge).or().ge(Student::getAge, 11))) .list(); return list; }
总结
1 你可以让他打印SQL语句，这样你就知道知道的SQL了
2 我遇到的情况是不报错，不打印SQL，那只能DEBUG
3 手写SQL在mapper中也行
