建站 哪个网站系统好用,上海工装设计公司排名,dw如何做网站登陆验证,网页设计可以从事什么工作文章目录 1. $eq 比较查询操作符1.1 基本类型字段1.2 嵌入式文档字段1.3 数组字段 2. $eleMatch 数组查询操作符2.1 基本类型数组字段2.2 基本类型数组字段2.3 嵌入式文档数组字段2.4 嵌入式文档数组字段 1. $eq 比较查询操作符
$eq 操作符匹配字段值等于指定值的文档。
db.c… 文章目录 1. $eq 比较查询操作符1.1 基本类型字段1.2 嵌入式文档字段1.3 数组字段 2. $eleMatch 数组查询操作符2.1 基本类型数组字段2.2 基本类型数组字段2.3 嵌入式文档数组字段2.4 嵌入式文档数组字段 1. $eq 比较查询操作符
$eq 操作符匹配字段值等于指定值的文档。
db.colletion.find({{ field: { $eq: value } }
})$eq 运算符等同于下面的形式但 value 是正则表达式的情况除外。
db.colletion.find({{ field: value }
})1.1 基本类型字段
构造测试数据
db.inventory.drop()db.inventory.insertMany( [{ _id: 1, item: { name: ab, code: 123 }, qty: 15, tags: [ A, B, C ] },{ _id: 2, item: { name: cd, code: 123 }, qty: 20, tags: [ B ] },{ _id: 3, item: { name: ij, code: 456 }, qty: 25, tags: [ A, B ] },{ _id: 4, item: { name: xy, code: 456 }, qty: 30, tags: [ B, A ] },{ _id: 5, item: { name: mn, code: 000 }, qty: 20, tags: [ [ A, B ], C ] }
] )查询 qty20 的所有文档
db.inventory.find({qty: {$eq: 20}
})db.inventory.find({qty: 20
})// 1
{_id: 2,item: {name: cd,code: 123},qty: 20,tags: [B]
}// 2
{_id: 5,item: {name: mn,code: 000},qty: 20,tags: [[A,B],C]
}Document(collection inventory)
Data
public class Inventory {Idprivate int id;private Item item;private int qty;private ListObject tags;Datapublic static class Item {private String name;private String code;}
}Test
public void queryTest() {//构造查询条件Query query new Query();query.addCriteria(Criteria.where(qty).is(20));//执行查询 ListInventory inventoryList mongoTemplate.find(query, Inventory.class);inventoryList.forEach(System.out::println);//Inventory(id2, itemInventory.Item(namecd, code123), qty20, tags[B])//Inventory(id5, itemInventory.Item(namemn, code000), qty20, tags[[A, B], C])
}1.2 嵌入式文档字段
构造测试数据
db.inventory.drop()db.inventory.insertMany( [{ _id: 1, item: { name: ab, code: 123 }, qty: 15, tags: [ A, B, C ] },{ _id: 2, item: { name: cd, code: 123 }, qty: 20, tags: [ B ] },{ _id: 3, item: { name: ij, code: 456 }, qty: 25, tags: [ A, B ] },{ _id: 4, item: { name: xy, code: 456 }, qty: 30, tags: [ B, A ] },{ _id: 5, item: { name: mn, code: 000 }, qty: 20, tags: [ [ A, B ], C ] }
] )查询 “item.name”“ab” 的所有文档
db.inventory.find({item.name: {$eq: ab}
})db.inventory.find({item.name: ab
})// 1
{_id: 1,item: {name: ab,code: 123},qty: 15,tags: [A,B,C]
}Test
public void queryTest() {//构造查询条件Query query new Query();query.addCriteria(Criteria.where(item.name).is(ab));//执行查询ListInventory inventoryList mongoTemplate.find(query, Inventory.class);inventoryList.forEach(System.out::println);//Inventory(id1, itemInventory.Item(nameab, code123), qty15, tags[A, B, C])
}1.3 数组字段
构造测试数据
db.inventory.drop()db.inventory.insertMany([{ _id : 1, item : abc1, description: product 1, qty: 300 },{ _id : 2, item : abc2, description: product 2, qty: 200 },{ _id : 3, item : xyz1, description: product 3, qty: 250 },{ _id : 4, item : VWZ1, description: product 4, qty: 300 },{ _id : 5, item : VWZ2, description: product 5, qty: 180 }
])查询 tags 数组包含 “A” 的所有文档
db.inventory.find({tags: {$eq: A}
})db.inventory.find({tags: A
})// 1
{_id: 1,item: {name: ab,code: 123},qty: 15,tags: [A,B,C]
}// 2
{_id: 3,item: {name: ij,code: 456},qty: 25,tags: [A,B]
}// 3
{_id: 4,item: {name: xy,code: 456},qty: 30,tags: [B,A]
}Test
public void queryTest() {//构造查询条件Query query new Query();query.addCriteria(Criteria.where(tags).is(A));//执行查询ListInventory inventoryList mongoTemplate.find(query, Inventory.class);//打印inventoryList.forEach(System.out::println);//Inventory(id1, itemInventory.Item(nameab, code123), qty15, tags[A, B, C])//Inventory(id3, itemInventory.Item(nameij, code456), qty25, tags[A, B])//Inventory(id4, itemInventory.Item(namexy, code456), qty30, tags[B, A])
}2. $eleMatch 数组查询操作符
$elemMatch 操作符匹配包含数组字段的文档该字段至少有一个元素与所有指定的查询条件匹配。
db.collection.find({ arrayField: { $elemMatch: { condition1, condition2 } } })2.1 基本类型数组字段
构造测试数据
db.student.drop()db.student.insertMany([{ _id: 1, scores: [ 82, 85, 88 ] },{ _id: 2, scorse: [ 75, 88, 89 ] }
])查询 scores 数组中至少包含一个大于等于80并且小于85的文档
db.student.find({ scores: { $elemMatch: { $gte: 80, $lt: 85 } }
})// 1
{_id: 1,scores: [82,85,88]
}Data
Document(collection students)
public class Student {Idprivate int id;private ListInteger scores;
}Test
public void queryTest() {// 构建查询条件Query query new Query();Criteria criteria Criteria.where(scores).elemMatch(Criteria.where($gte).is(80).and($lt).is(85));query.addCriteria(criteria);// 执行查询ListStudent student mongoTemplate.find(query, Student.class, student);student.forEach(System.out::println);//Student(id1, scores[82, 85, 88])
}2.2 基本类型数组字段
构造测试数据
db.user.drop()db.user.insertMany([{ name: Alice, age: 25, email: aliceexample.com, hobbies: [reading, writing, music] },{ name: John, age: 30, email: Johnqq.com, hobbies: [reading, gaming, traveling] },{ name: Jane, age: 25, email: Janeqq.com, hobbies: [sports, music, cooking] },{ name: Mike, age: 35, email: Mikeqq.com, hobbies: [reading, writing, painting] }
]) 查询age30 并且 hobbies 数组中包含 reading 的文档
db.student.find({ age: { $gte: 30 }, hobbies: { $elemMatch: { $eq: reading } }
})// 1
{_id: ObjectId(66a4ab82f074c9a04808d562),name: John,age: 30,email: Johnqq.com,hobbies: [reading,gaming,traveling]
}// 2
{_id: ObjectId(66a4ab82f074c9a04808d564),name: Mike,age: 35,email: Mikeqq.com,hobbies: [reading,writing,painting]
}Data
Document(collection user)
public class User {Idprivate String id;private String name;private Integer age;private String email;private ListString hobbies;public User(String name,Integer age,String email,ListString hobbies){this.name name;this.age age;this.email email;this.hobbies hobbies;}
}Test
public void queryTest() {// 构建查询条件Query query new Query();Criteria criteria Criteria.where(age).gte(30).and(hobbies).elemMatch(Criteria.where($eq).is(reading));query.addCriteria(criteria);// 执行查询ListUser userList mongoTemplate.find(query, User.class, user);userList.forEach(System.out::println);//User(id66a4ab82f074c9a04808d562, nameJohn, age30, emailJohnqq.com, hobbies[reading, gaming, traveling])//User(id66a4ab82f074c9a04808d564, nameMike, age35, emailMikeqq.com, hobbies[reading, writing, painting])
}2.3 嵌入式文档数组字段
构造测试数据
db.survey.drop()db.survey.insertMany( [{ _id: 1, results: [ { product: abc, score: 10 },{ product: xyz, score: 5 } ] },{ _id: 2, results: [ { product: abc, score: 8 },{ product: xyz, score: 7 } ] },{ _id: 3, results: [ { product: abc, score: 7 },{ product: xyz, score: 8 } ] },{ _id: 4, results: [ { product: abc, score: 7 },{ product: def, score: 8 } ] },{ _id: 5, results: { product: xyz, score: 9 } }
] )查询 results 数组中 product“def” 的文档
db.survey.find({ results: { $elemMatch: { product: def } }
})db.survey.find({ results.product: def }
)// 1
{_id: 4,results: [{product: abc,score: 7},{product: def,score: 8}]
}Data
Document(collection survey)
public class Survey {Idprivate int id;private ListResult results;Datapublic class Result {private String item;private int score;}
}Test
public void queryTest() {// 构建查询条件Query query new Query();Criteria criteria Criteria.where(results).elemMatch(Criteria.where(product).is(def));query.addCriteria(criteria);// 执行查询ListSurvey surveys mongoTemplate.find(query, Survey.class);surveys.forEach(System.out::println);//Survey(id4, results[Survey.Result(itemnull, score7), Survey.Result(itemnull, score8)])
}2.4 嵌入式文档数组字段
查询 results 数组中 productxyzscore8 的文档
db.survey.find({ results: { $elemMatch: { product: xyz, score: { $gte: 8 } } }
})// 1
{_id: 3,results: [{product: abc,score: 7},{product: xyz,score: 8}]
}Test
public void queryTest() {// 构建查询条件Query query new Query();Criteria criteria Criteria.where(results).elemMatch(Criteria.where(product).is(xyz).and(score).gte(8));query.addCriteria(criteria);// 执行查询ListSurvey surveys mongoTemplate.find(query, Survey.class);surveys.forEach(System.out::println);//Survey(id3, results[Survey.Result(itemnull, score7), Survey.Result(itemnull, score8)])
}
