CRUD增刪改查：
@GetMapping、@DeleteMapping、@PostMapping、@PutMapping
一、查詢
- 在進行方法名解析時會先去掉多餘的前綴，比如find、findBy、read、readBy、get、getBy，然後對剩下部分進行解析，並且如果方法最後一個參數時 Sort 或 Pageable 類型，也會提取相關信息
- 比如：findByNameLikeAndAgeGreaterThan
- 剔除findBy
- 判斷nameLikeAndAgeGreaterThan（根據POJO規範，首字母變小寫）是否爲返回對象 User 的一個屬性，如果是，則根據該屬性進行查詢，如果沒有該屬性，則進行下一步
- 從右往左截取第一個大寫字母開頭的字符串（此處爲Than），然後檢查剩下的字符串是否爲 User 的一個屬性，如果是，則根據該屬性進行查詢，否則重複第2步，直到找出 name 爲 User 的屬性
- 從已截取的部分後面開始，重新第 1 步開始（剔除條件語句），循環，直到把方法名處理完畢
- 通過獲取的操作、條件和屬性、帶入參數值，生成查詢
| Keyword | Sample | JPQL snippet |
|---|---|---|
| And | findByLastnameAndFirstname | … where x.lastname = ?1 and x.firstname = ?2 |
| Or | findByLastnameOrFirstname | … where x.lastname = ?1 or x.firstname = ?2 |
| Is,Equals | findByFirstname,findByFirstnameIs,findByFirstnameEquals | … where x.firstname = ?1 |
| Between | findByStartDateBetween | … where x.startDate between ?1 and ?2 |
| LessThan | findByAgeLessThan | … where x.age < ?1 |
| LessThanEqual | findByAgeLessThanEqual | … where x.age ⇐ ?1 |
| GreaterThan | findByAgeGreaterThan | … where x.age > ?1 |
| GreaterThanEqual | findByAgeGreaterThanEqual | … where x.age >= ?1 |
| After | findByStartDateAfter | … where x.startDate > ?1 |
| Before | findByStartDateBefore | … where x.startDate < ?1 |
| IsNull | findByAgeIsNull | … where x.age is null |
| IsNotNull,NotNull | findByAge(Is)NotNull | … where x.age not null |
| Like | findByFirstnameLike | … where x.firstname like ?1 |
| NotLike | findByFirstnameNotLike | … where x.firstname not like ?1 |
| StartingWith | findByFirstnameStartingWith | … where x.firstname like ?1 (parameter bound with appended %) |
| EndingWith | findByFirstnameEndingWith | … where x.firstname like ?1 (parameter bound with prepended %) |
| Containing | findByFirstnameContaining | … where x.firstname like ?1 (parameter bound wrapped in %) |
| OrderBy | findByAgeOrderByLastnameDesc | … where x.age = ?1 order by x.lastname desc |
| Not | findByLastnameNot | … where x.lastname <> ?1 |
| In | findByAgeIn(Collection ages) | … where x.age in ?1 |
| NotIn | findByAgeNotIn(Collection age) | … where x.age not in ?1 |
| True | findByActiveTrue() | … where x.active = true |
| False | findByActiveFalse() | … where x.active = false |
| IgnoreCase | findByFirstnameIgnoreCase | … where UPPER(x.firstame) = UPPER(?1) |
二、刪
DeleteBy + 上述關鍵字
三、增、改
repository.save() 方法
執行時：根據ID在數據庫裏查詢，若查不到該Id，則執行插入SQL。
若查到該Id，則執行updata操作。