- 在springdata jpa 中我们经常会对数据库进行各种各样的CURD操作。比如，查询操作。当然对于一些简单业务的CURD操作由jpa自带的JpaRepository接口就行已经可以满足了，但是往往在开发中需求的复杂程度是不能够预测的，所以构建一些能自适应相对复杂业务的CURD操作是很有必要的。这时候我们也可以选择采用@Query注解进行原生SQL语句的编写、获取采用@Query注解编写SpEL语句进行着对数据库的CURD操作。而现在我要说的是采用jpa 提供的方法名派生查询的方式。比如在Person类中有lastName属性，就可以构造一个这样的查询方法：findPersonByLastName(String lastName)。意思是根据lastName属性值查询响应的Person对象，而Person类映射着数据表，自然而然地形成了间接起到了查询数据表的操作。当然前提是Person的持久化接口先继承了jpa的持久化接口JpaRepository。下面是方法名派生查询中能用到的关键字：
| 关键字 | 样品方法 | SQPL片段 | 原生SQL | 备注 |
| And | findPersonByLastNameAndFirstName(String lastName，String firstName) | ...where x.lastName = ?1 and x.firstName = ?2 | ...where lastName = 1? and firstName = 2? | & |
| Or | findPersonByLastnameOrFirstname(String lastName，String firstName) | ...where x.lastName= ?1 or x.firstName = ?2 | ...where lastName = ?1 or firstName = ?2 | | |
| Is、Equals |
findPersonByLastName(String lastName) findPersonByLastNameIs(String lastName) findPersonByLastNameEquals(String lastName) |
...where x.lastName= ?1 | ...where lastName = ?1 | = |
| Between | findPersonByAge(int minAge, int maxAge) | ...where x.age between ?1 and ?2 | ...where age between ?1 and ?2 | >= and < |
| LessThan | findPersonByAgeLessThan(int age) | ...where x.age < ?1 | ...where age < ?1 | < |
| LessThanEqual | findPersonByAgeLessThanEqual(int age) | ...where x.age <= ?1 | ...where age <= ?1 | <= |
| GreaterThan | findPersonByAgeGreaterThanEqual(int age) | ...where x.age > ?1 | ...where age > ?1 | > |
| GreaterThanEqual | findPersonByAgeGreaterThanEqual(int age) | ...where x.age >= ?1 | ...where age >= ?1 | >= |
| After | findPersonByStartDateAfter(Date startDate) | ...where x.startDate > ?1 | ...where startDate > ?1 | > |
| Before | findPersonByStartDateBefore(Date startDate) | ...where x.startDate < ?1 | ...where startDate < ?1 | < |
| isNull、Null | findPersonByLastNameIsNull/findPersonByLastNameNull | ...where x.lastName is null | ...where lastName is null | is null |
| isNotNull、NotNull | findPersonByLastNameisNotNull/findPersonByLastNameNotNull | ...where x.lastName is not null | ...where lastName is not null | is not null |
| Like | findPersonByLastNameLike(String lastName) | ...where x.lastName like '%' + ?1 + '%' | ...where lastName like ?1 | like |
| NotLike | findPersonByLastNameNotLike(String lastName) | ...where x.lastName not like ?1 | ...where lastName not like ?1 | not like |
| StartingWith | findPersonByLastNameStartingWith(String lastName) | ...where x.lastName like '%' + ?1 | ...where lastName like '%' + ?1 | like |
| EndingWith | findPersonByLastNameEndingWith(String lastName) | ...where x.lastName like ?1 + '%' | ...where lastName like ?1 + '%' | like |
| Containing | findPersonByLastNameContaiting(String lastName) | ...where x.lastName like '%' + ?1 + '%' | ...where lastName like '%' + ?1 + '%' | like |
| OrderBy | findPersonByOrderByLastNameDesc/Asc | ...order by x.lastName desc | ...order by lastName desc | order by |
| Not | findPersonByLastNameNot(String lastName) | ...where x.lastName <> ?1 | ...where lastName <> ?1 | <> / != |
| In | findPersonByAgeIn(List<Integer> ages) | ...where x.lastName in(?1) | ...where lastName in(?1) | in |
| NotIn | findPersonByAgeNotIn(List<Integer> ages) | ...where x.lastName not in(?1) | ...where lastName not in(?1) | not in |
| True | findPersonByFlagTrue(Boolean flag) | ...where x.flag = true | ...where flag = true | = |
| False | findPersonByFlagFalse(Boolean flag) | ...where x.flag = false | ...where flag = false | = |
| IgnoreCase | findPersonByLaseNameIgnoreCase(String lastName) | ...where upper(x.lastName) = upper(?1) | ...where upper(lastName) = upper(?1) | = |