- 查詢語言：Query Language
- 條件表達式：where+having+on
- 輸入參數：支持位置參數 ?1，和命名參數 :userName，但這兩者不能混用
- 條件組合：屬性導航：user.userName，一元運算 + -，邏輯操作 NOT AND OR，
比較Comparison：= > >= < <= <>
區間Between：[NOT] BETWEEN，支持數字、字符串、日期
集合In：[NOT] IN，f in ('a', 'b') 等價於 f='a' or f='b'
相似Like：[NOT] LIKE，支持單個字符_、多個字符%、轉義字符\_
空值Null：IS [NOT] NULL，
空集合：IS [NOT] EMPTY，select o from Order o where o.lineItems is empty，
集合成員：[NOT] MEMBER OF，select p from Person p where 'Joe' member of p.nicknames;
存在性Exist：[NOT] EXISTS，select emp from Employee emp where exists ( select spouseEmp from Employee spouseEmp where spouseEmp = emp.spouse );//spouse配偶
全部或任意：All+Any+Some，select emp from Employee where emp.salary > All { select m.salary from Manager m where m.department=emp.department };//部門高新員工
子查詢Subquery：select goodCustomer from Customer goodCustomer where goodCustomer.balanceOwed < ( select avg(c.balanceOwed)/2.0 from Customer c );//優質客戶 - 原生標准操作
字符串：concat，substr，trim，lower，
算術：abs，sqrt，mod，size，index（select w.name from Course c join c.studentsWaitlist w where c.name='Calculus' and index(w)=0;）
聚合：count，max，min，avg，sum，distinct
日期：current_date，current_time，current_timestamp
過程調用：select c from Customer c where function( 'hasGoodCredit', c.balance, c.creditLimit );
分支語句：update Employee e set e.salary =
case e.rating when 1 then e.salary*1.1
when 2 then e.salary*1.05
else e.salary*1.01
end
類型判斷：select e from Employee e where type(e) in ( Exempt, Contractor ) - 分組和結果限定
select c.status, avg(c.filledOrderCount), count(c) from Customer c group by c.status having c.status in ( 1, 2 );//統計狀態1和2的客戶信息
select c, count(o) from Customer c Join c.orders o group by c having count(o) >= 5;//查詢訂單數大於等於5的客戶 - 排序
select o from Customer c JOIN c.orders o JOIN c.address a where a.state='CA' order by o.quantity DESC, o.totalcost;//總量倒序，花費升序 - 批量更新和刪除
delete from Customer c where c.status='inactive' and c.orders is empty;//刪除未激活且沒有訂單的用戶
update Employee e set e.address.building=22 where e.address.building=14 and e.project='Java EE';//修改Java EE項目組成員的地址 - 查詢條件：Criteria，標准條件
- CriteriaBuilder，@PersistenceUnit EntityManagerFactory.getCriteriaBuilder(); 或 @PersistenceContext EntityManager.getCriteriaBuilder();
CriteriaQuery<T> createQuery(Class<T> resultClass);//創建查詢，返回結果類型為resultClass
CriteriaQuery<Tuple> createTupleQuery();//創建查詢，返回元組類型，Tuple包含多個TupleElements
CriteriaUpdate<T> createCriteriaUpdate(Class<T> targetEntity);//創建對targetEntity的批量修改操作
CriteriaDelete<T> createCriteriaDelete(Class<T> targetEntity);//創建對targetEntity的批量刪除操作
CompoundSelection<Tuple> tuple(Selection<?>... selections);//創建tupe-valued查詢
CompoundSelection<Object[]> array(Selection<?>... selections);//創建array-valued查詢
Order asc(Expression<?> x);//創建表達式值的升序，desc為降序
Expression<Double> avg(Expression<N> x);//計算平均值，還有count[Distinct]，sum，max+min（數字），greatest+least（字符串、日期等），
Predicate exists(Subquery<?> subquery);//判斷子查詢是否存在，還有all，some，any，isTrue，isFalse，is[Not]Null
Predicate and(Expression<Boolean> x, Expression<Boolean> y);//邏輯與，還有or，not
Predicate or(Predicate... restrictions);//多個條件或，還有與and
Predicate conjunction();//條件與，沒有時返回true；還有disjunction，條件或，沒有時返回false；
Predicate equal(Expression<?> x, Expression<?> y);//判斷是否相等，還有greaterThan[OrEqualTo]（Comparable），between，gt+ge+lt+le（Number）
Predicate notEqual(Expression<?> x, Object value);//判斷是否不等，還有lessThan[OrEqualTo]，like+notLike
Expression<Number> sum(Expression<?> x, N y);//算術運算，還有neg+abs+prod積+diff差+quot商+mod模+sqrt平方根+concat+substring+trim+upper+length+locate
Expression<Long> toLong(Expression<?> x);//類型轉換，還有Integer+Float+Double+BigDecimal+BigInteger+String
Expression<T> literal(T value);//轉換常量值，
Predicate is[Not]Empty(Expression<c> collection);//測試集合非空，還有size+is[Not]Member，q.where(cb.isEmpty(order.get("lineItems"))); => where order.lineItems is empty
Expression<Collection<V>> values(M map);//從map的values()創建集合條件，還有keys
Expression<java.sql.Date> currentDate();//當前日期，還有java.sql.Time=currentTime，java.sql.Timestamp=currentTimestamp
In<T> in(Expression<T> expression);//q.having( cb.in( customer.get("status").value(1).value(2) ) ); => having c.status in ( 1,2 ) - CriteriaQuery -> AbstractQuery
Root<X> from(Class<X> entityClass);//獲得查詢根，或與已有根計算笛卡爾積
AbstractQuery<T> where(Predicate... restrictions);//限定條件（替換之間的條件）
AbstractQuery<T> groupBy(Expression<?>... grouping);//分組，還有having+orderBy
CriteriaQuery<T> select(Selection<?> selection);//設置選擇結果
CriteriaQuery<T> multiselect(Selection<?>... selections);//多個選擇結果
執行復雜條件查詢
@PersistenceContext EntityManager em;
TypedQuery<T> query = em.createQuery(CriteriaQuery<T> cq);//創建查詢對象
query.setFirstResult().setMaxResults().getResultList();//獲得查詢結果 - CriteriaUpdate+CriteriaDelete，有from+where
CriteriaUpdate<T> set(Path attribute, X value);//更新屬性
update customer c set c.status='outstanding' where c.balance<1000;
CriteriaUpdaate<Customer> q=cb.createCriteriaUpdate(Customer.class);
Root<Customer> c=q.from(Customer.class);
q.set(c.get("status"), "outstanding")
.where( cb.lt(c.get("balance"), 1000) ); - Root實體根+Join表連接 -> From查詢 -> Path路徑+Predicate與或 -> Expression表達式 -> Selection選擇返回值
Selection alias(String alias);//設置別名
Predicate isNull();//是否空，還有isNotNull+
Predicate in(Object... values);//集合元素，
Path<Y> get(String attributeName);//獲取路徑
Join join(String attributeName, JoinType type);//鏈接屬性表，還有joinCollection，joinSet，joinList（t.index()限定多個對象的個數），joinMap（t.key()限定對象映射的key）
Join on(Predicate... restrictions);//表鏈接 - 查詢樣例，最好先組織SQL和JPQL語句，然后再翻譯為對象方法調用
- 獲取全部或限定條件，select c from customer c where c.name="Jack";
CriteriaQuery<Customer> q = CriteriaBuilder.createQuery(Customer.class);//返回類型為Customer
Root<Customer> customer = q.from(Customer.class);//查詢表Customer
q.select(customer);//查詢整個Customer對象
q.where(cb.equal( customer.get("name"), 'Jack'));//限定name="Jack"的對象 - 連接統計，select s.name, count(p) from Supplier s left join s.products on p.status='inStock' group by s.name;
CriteriaQuery<Tuple> q = cb.createTupleQuery();//配合后面的multiselect
Root<Supplier> s = q.from(Supplier.class);//
Join<Supplier, Product> p = s.join("products", JoinType.LEFT);//連接產品表
p.on(cb.equal(p.get("status"), "inStock"));//限定連接條件，s.join("products", JoinType.LEFT).on(cb.equal(p.get("status"), "inStock"));
q.groupBy( s.get("name") );
q.multiselect( s.get("name"), cb.count(p) );//等價於q.select(cb.tuple(s.get("name"), cb.count(p)));，還有cb.array，cb.construct(Type.class, ... args) - 深度獲取fetch join，select d from Department d left join fetch d.employees where d.deptno=1;
CriteriaQuery<Department> q = cb.createQuery(Department.class);
Root<Department> d = q.from(Department.class);
d.fetch("employees", JoinType.LEFT);//查詢結果中d.employees有值
q.where( cb.equal(d.get("deptno"), 1) );
q.select(d); - 路徑導航，select p.vendor from Employee e join e.contactInfo.phones p where e.contactInfo.address.zipcode="95054";
CriteriaQuery<Vendor> q = cb.createQuery<Vendor.class>;//返回結果為Vendor
Root<Employee> e = q.from(Employee.class);//從Employee開始查詢
Join<ContactInfo, Phone> phone = e.join("contactInfo").join("phones");//連接多張表
q.where( cb.equal(e.get("contactInfo").get("address").get("zipcode"), "95054") );
q.select( phone.get("vendor") ); - 類型轉換，select b.ISBN from Order o join treat(o.product AS Book) b;
CriteriaQuery<String> q = cb.createQuery(String.class);
Root<Order> order = q.from(Order.class);
Join<Order, Book> book = cb.treat( order.join("product"), Book.class);
q.select( book.get("isbn") ); - 分支查詢，
select e.name ,
case when e.rating=1 then e.salary*1.1
when e.rating=2 then e.salary*1.2
else e.salary&1.01
from Employee e where e.department.name='Engineering';
CriteriaQuery<Tuple> q=cb.createTupleQuery();
Root<Employee> e=q.from(Employee.class);
q.where( cb.equal(e.get("department").get("name"), "Engineering") );
q.multiselect( e.get("name"), cb.selectCase()
.when(cb.equal(e.get("rating"), 1), cb.prod(e.get("salary"), 1.1))
.when(cb.equal(e.get("rating"), 2), prod(e.get("salary"), 1.2))//這里需要常量的話調用cb.literal("value")
.otherWise(cb.prod(e.get("salary"), 1.01)) ); - 參數
select c from Customer c where c.status = :stat;
CriteriaQuery<Customer> q=cb.createQuery(Customer.class);
Root<Customer> c=q.from(Customer.class);
ParameterExpression<Integer> param=cb.parameter(Integer.class, "stat");
q.select(c).where(cb.equal(c.get("status"), param)); - 子查詢，select goodCustomer from Customer goodCustomer where goodCustomer.balanceOwed < ( select avg(c.balanceOwed) from Customer c );
CriteriaQuery<Customer> q=cb.createQuery(Customer.class);
Root<Customer> goodCustomer=q.from(Customer.class);
Subquery<Double> sq=q.subquery(Double.class);//子查詢返回double值
Root<Customer> customer=sq.from(Customer.class);
q.where(cb.lt(goodCustomer.get("balanceOwed"), sq.select(cb.avg(customer.get("balanceOwed")))));//goodCustomer.balanceOwed < avg(customer.balanceOwed)
q.select(goodCustomer);
select emp from Employee emp where emp.salary > all ( select m.salary from Manager m where m.department=emp.department );
CriteriaQuery<Employee> q=cb.createQuery(Employee.class);
Root<Employee> emp=q.from(Employee.class);
Subquery<BigDecimal> sq=q.subquery(BigDecimal.class);
Root<Manager> manager=sq.from(Manager.class);
sq.select(manager.get("salary"));
sq.where(cb.equals(manager.get("department"), emp.get("department")));
q.select(emp).where(cb.gt(emp.get("salary"), cb.all(sq))); - EntityManager
- 獲得EntityManager
@PersistenceContext EntityManager em;
@PersistenceUnit EntityManagerFactory emf; emf.createEntityManager()//
javax.persistence.Persistence.createEntityManagerFactory("order");//從persistence.xml文件讀取unit配置 - 統計接口及實現：
調用優先級Criteria API > Java Persistence Query Language > SQL
有些統計語句可能是在很復雜只好執行原始的SQL語句了（sql條件需在可控范圍內，最好檢查一下參數安全性），但前兩種在適當的時候還是應當多用的（防SQL注入）
public class TongjiReposityImpl implements TongjiRepository {@PersistenceContext private EntityManager entityManager;@Overridepublic CriteriaBuilder builder() { //Criteria APIreturn entityManager.getCriteriaBuilder();}@Overridepublic long count(CriteriaQuery<Long> query) {TypedQuery<Long> typedQuery = entityManager.createQuery(query);return typedQuery.getSingleResult();}@Overridepublic Object[] sums(CriteriaQuery<Tuple> query) {List<Tuple> list = list(query, 0, 0);return list!=null && list.size()>0 ? list.get(0).toArray() : null;}@Overridepublic List<Tuple> list(CriteriaQuery<Tuple> query, int firstResult, int maxResults) {TypedQuery<Tuple> typedQuery = entityManager.createQuery(query);typedQuery.setFirstResult(firstResult);if(maxResults>0) typedQuery.setMaxResults(maxResults);return typedQuery.getResultList();}@Overridepublic int count(String jpql, Object... args) { //Java Persistence Query LanguageQuery query = entityManager.createQuery(jpql);if(args!=null && args.length>0) {for(int i=0; i<args.length; i++) {query.setParameter(i+1, args[i]);}}return ((Number)query.getSingleResult()).intValue();}@Overridepublic Object[] sums(String jpql, Object... args) {List<?> list = list(jpql, args);if(list!=null && list.size()>0) {Object obj = list.get(0);if(obj instanceof Object[]) {return (Object[])obj;}else {return new Object[] {obj};}}return null;}@Overridepublic List<?> list(String jpql, Object... args) {Query query = entityManager.createQuery(jpql);if(args!=null && args.length>0) {for(int i=0; i<args.length; i++) {query.setParameter(i+1, args[i]);}}return query.getResultList();}@Overridepublic int count(String sql) { //SQLQuery query = entityManager.createNativeQuery(sql);return ((Number)query.getSingleResult()).intValue();}@Overridepublic Object[] sums(String sql) {List<?> list = list(sql);if(list!=null && list.size()>0) {Object obj = list.get(0);if(obj instanceof Object[]) {return (Object[])obj;}else {return new Object[] {obj};}}return null;}@Overridepublic List<?> list(String sql) {Query query = entityManager.createNativeQuery(sql);return query.getResultList();}} - sql輔助生成工具類
/*** select column from table where condition group by column having condition order by column limit from,length*/public class SqlBuilder {private String select;private String from;private StringBuilder where = new StringBuilder();private String groupBy;private String having;private String orderBy;private String limit;public static SqlBuilder builder() {return new SqlBuilder();}/*** @param select* <li>** <li>column1,column2,...* <li>count(column1),sum(column2),avg(column3),...* <li>user.id,user.name,account.amount,...*/public SqlBuilder select(String select) {this.select = select;return this;}/*** @param from* <li>ts_user* <li>ts_user u left join ts_account a on u.ts_user_id = a.ts_user_id* <li>jpql: TsUser user left join user.tsAccount account*/public SqlBuilder from(String from) {this.from = from;return this;}/*** @param where* <li>null, to reset where* <li>name like '%Jack%'* <li>id in (1,2,3)* <li>exists (select a.id from acount a where a.user_id=user.id)* <li>name is empty*/public SqlBuilder where(String where) {if(StringUtils.isEmpty(where)) {this.where.setLength(0);}else {this.where.append(" and " + where);}return this;}/*** @param columnOperator* <li>column1 >=* <li>column2 !=*/public SqlBuilder where(String columnOperator, Object value) {if(!StringUtils.isEmpty(value)) {where.append(" and " + columnOperator + " '" + sqlParam(value.toString()) + "'");}return this;}public SqlBuilder groupBy(String groupBy) {this.groupBy = groupBy;return this;}public SqlBuilder having(String having) {this.having = having;return this;}public SqlBuilder orderBy(String orderBy) {this.orderBy = orderBy;return this;}/*** @param limit* <li>limit 0,10*/public SqlBuilder limit(String limit) {this.limit = limit;return this;}public SqlBuilder eq(String column, Object value) {if(!StringUtils.isEmpty(value)) {where.append(" and " + column + " = '" + sqlParam(value.toString()) + "'");}return this;}public SqlBuilder ne(String column, Object value) {if(!StringUtils.isEmpty(value)) {where.append(" and " + column + " != '" + sqlParam(value.toString()) + "'");}return this;}public SqlBuilder like(String column, Object value) {if(!StringUtils.isEmpty(value)) {where.append(" and " + column + " like '%" + sqlParam(value.toString()) + "%'");}return this;}public SqlBuilder notLike(String column, Object value) {if(!StringUtils.isEmpty(value)) {where.append(" and " + column + " not like '%" + sqlParam(value.toString()) + "%'");}return this;}public SqlBuilder in(String column, Collection<?> value) {if(!CollectionUtils.isEmpty(value)) {where.append(" and " + column + " in (" + StringUtils.collectionToDelimitedString(value, ",", "'", "'") + ")");}return this;}public SqlBuilder notIn(String column, Collection<?> value) {if(!CollectionUtils.isEmpty(value)) {where.append(" and " + column + " not in (" + StringUtils.collectionToDelimitedString(value, ",", "'", "'") + ")");}return this;}public SqlBuilder gt(String column, Object value) {if(!StringUtils.isEmpty(value)) {where.append(" and " + column + " > '" + sqlParam(value.toString()) + "'");}return this;}public SqlBuilder gte(String column, Object value) {if(!StringUtils.isEmpty(value)) {where.append(" and " + column + " >= '" + sqlParam(value.toString()) + "'");}return this;}public SqlBuilder lt(String column, Object value) {if(!StringUtils.isEmpty(value)) {where.append(" and " + column + " < '" + sqlParam(value.toString()) + "'");}return this;}public SqlBuilder lte(String column, Object value) {if(!StringUtils.isEmpty(value)) {where.append(" and " + column + " <= '" + sqlParam(value.toString()) + "'");}return this;}public SqlBuilder between(String column, Object from, Object to) {if(StringUtils.isEmpty(from) && StringUtils.isEmpty(to)) return this;if(!StringUtils.isEmpty(from)) where.append(" and " + column + " >= '" + sqlParam(from.toString()) + "'");else if(!StringUtils.isEmpty(to)) where.append(" and " + column + " <= '" + sqlParam(to.toString()) + "'");else where.append(" and " + column + " between '" + sqlParam(from.toString()) + "' and '" + sqlParam(to.toString()) + "'");return this;}public String sql() {if(select == null || from == null) //必須得有selece和from部分throw new RuntimeException("sql must contain select + from parts.");StringBuilder sql = new StringBuilder("select " + select+" from "+from);if(where.length() > 4) sql.append(" where " + where.substring(5));if(groupBy != null) sql.append(" group by " + groupBy);if(having != null) sql.append(" having " + having);if(orderBy != null) sql.append(" order by " + orderBy);if(limit != null) sql.append(" limit " + limit);return sql.toString();}//過濾掉引號'"，逗號,分號;注釋號--等sql敏感符號public static String sqlParam(String sqlParam) {return sqlParam.replaceAll("([';]+|(--)+)", "");}} - jpql輔助工具類，與SqlBuilder類似
public class JpqlBuilder {private String select;private String from;private StringBuilder where = new StringBuilder();private List<Object> args = new ArrayList<Object>();private String groupBy;private String having;private String orderBy;private String limit;public static JpqlBuilder builder() {return new JpqlBuilder();}/*** @param select* <li>** <li>user.id,user.name,account.amount,...*/public JpqlBuilder select(String select) {this.select = select;return this;}/*** @param from* <li>jpql: TsUser user left join user.tsAccount account*/public JpqlBuilder from(String from) {this.from = from;return this;}/*** @param where* <li>null, to reset where* <li>name like '%Jack%'*/public JpqlBuilder where(String where) {if(StringUtils.isEmpty(where)) {this.where.setLength(0);args.clear();}else {this.where.append(" and " + where);}return this;}/*** @param columnOperator* <li>column1 >=* <li>column2 !=*/public JpqlBuilder where(String columnOperator, Object value) {if(!StringUtils.isEmpty(value)) {args.add(value);where.append(" and " + columnOperator + " ?" + args.size());}return this;}public JpqlBuilder groupBy(String groupBy) {this.groupBy = groupBy;return this;}public JpqlBuilder having(String having) {this.having = having;return this;}public JpqlBuilder orderBy(String orderBy) {this.orderBy = orderBy;return this;}/*** @param limit* <li>limit 0,10*/public JpqlBuilder limit(String limit) {this.limit = limit;return this;}public JpqlBuilder eq(String column, Object value) {if(!StringUtils.isEmpty(value)) {args.add(value);where.append(" and " + column + " = ?" + args.size());}return this;}public JpqlBuilder ne(String column, Object value) {if(!StringUtils.isEmpty(value)) {args.add(value);where.append(" and " + column + " != ?" + args.size());}return this;}public JpqlBuilder like(String column, Object value) {if(!StringUtils.isEmpty(value)) {args.add(value);where.append(" and " + column + " like ?" + args.size());}return this;}public JpqlBuilder notLike(String column, Object value) {if(!StringUtils.isEmpty(value)) {args.add(value);where.append(" and " + column + " not like ?" + args.size());}return this;}public JpqlBuilder in(String column, Collection<?> value) {if(!CollectionUtils.isEmpty(value)) {where.append(" and " + column + " in (");boolean first = true;for(Object obj : value) {args.add(obj);if(first) {first = false;where.append("?"+args.size());}else {where.append(" , ?"+args.size());}}where.append(")");}return this;}public JpqlBuilder notIn(String column, Collection<?> value) {if(!CollectionUtils.isEmpty(value)) {where.append(" and " + column + " not in (");boolean first = true;for(Object obj : value) {args.add(obj);if(first) {first = false;where.append("?"+args.size());}else {where.append(" , ?"+args.size());}}where.append(")");}return this;}public JpqlBuilder gt(String column, Object value) {if(!StringUtils.isEmpty(value)) {args.add(value);where.append(" and " + column + " > ?" + args.size());}return this;}public JpqlBuilder gte(String column, Object value) {if(!StringUtils.isEmpty(value)) {args.add(value);where.append(" and " + column + " >= ?" + args.size());}return this;}public JpqlBuilder lt(String column, Object value) {if(!StringUtils.isEmpty(value)) {args.add(value);where.append(" and " + column + " < ?" + args.size());}return this;}public JpqlBuilder lte(String column, Object value) {if(!StringUtils.isEmpty(value)) {args.add(value);where.append(" and " + column + " <= ?" + args.size());}return this;}public JpqlBuilder between(String column, Object from, Object to) {if(StringUtils.isEmpty(from) && StringUtils.isEmpty(to)) return this;if(!StringUtils.isEmpty(from)) {args.add(from);where.append(" and " + column + " >= ?" + args.size());}else if(!StringUtils.isEmpty(to)) {args.add(to);where.append(" and " + column + " <= ?" + args.size());}else {args.add(from);args.add(to);where.append(" and " + column + " between ?" + (args.size()-1) + " and ?" + args.size());}return this;}public String jpql() {if(select == null || from == null) //必須得有selece和from部分throw new RuntimeException("sql must contain select + from parts.");StringBuilder sql = new StringBuilder("select " + select+" from "+from);if(where.length() > 4) sql.append(" where " + where.substring(5));if(groupBy != null) sql.append(" group by " + groupBy);if(having != null) sql.append(" having " + having);if(orderBy != null) sql.append(" order by " + orderBy);if(limit != null) sql.append(" limit " + limit);return sql.toString();}public Object[] args() {return args.toArray();}}
JPA
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