内容简介:ArangoDB查询语言(AQL)类似于结构化查询语言(SQL) 在它的目的。两者都支持读取和修改集合数据,但AQL不支持数据定义操作,例如创建和删除数据库,集合和索引。
ArangoDB查询语言(AQL)类似于结构化查询语言(SQL) 在它的目的。两者都支持读取和修改集合数据,但AQL不支持数据定义操作,例如创建和删除数据库,集合和索引。
虽然有些关键字重叠,但AQL语法与 SQL 不同。例如,SQL WHERE和AQL FILTER子句是等效的,因为它们都定义了返回结果的条件。但是,SQL使用预定义的序列来确定WHERE语句必须在哪里出现。在AQL中,子句从左到右执行,因此FILTER查询中子句的位置决定了它的优先级。
尽管有这些差异,任何具有SQL背景的人都应该没有学习AQL的困难。
一、数据预览
本次使用的数据共有43条,每条数据包含姓氏、年龄、活动状态和特征等六个字段
其中每个特征都有一个随机字母作为文档密钥。特质标签有英文和德文。
地点由地名和经纬度组成:
二、基本的CRUD
创建集合:
在创建文档之前,需要创造一个放置它的集合,集合可以通过Web界面,arangosh或驱动程序来创建。AQL无法创建集合。
单击Web界面中的COLLECTIONS,然后单击Add Collection并键入 Charactersname。使用保存确认。新集合就出现在了列表中。
插入单个对象:
使用AQL插入文档
INSERT { "name": "Ned", "surname": "Stark", "alive": true, "age": 41, "traits": ["A","H","C","N","P"] } INTO Characters 复制代码
语法:
INSERT document INTO collectionName
该文档是一个对象,由属性键和值对组成。属性键的引号在AQL中是可选的。键总是字符串,而属性值可以有不同的类型:
- null
- boolean (true, false)
- number (integer and floating point)
- string
- array
- object
批量插入对象:
AQL不允许INSERT在单个查询中针对同一集合的多个操作。但是可以使用FOR循环体,插入多个文档。
LET data = [ { "name": "Robert", "surname": "Baratheon", "alive": false, "traits": ["A","H","C"] }, { "name": "Jaime", "surname": "Lannister", "alive": true, "age": 36, "traits": ["A","F","B"] }, { "name": "Catelyn", "surname": "Stark", "alive": false, "age": 40, "traits": ["D","H","C"] }, { "name": "Cersei", "surname": "Lannister", "alive": true, "age": 36, "traits": ["H","E","F"] }, { "name": "Daenerys", "surname": "Targaryen", "alive": true, "age": 16, "traits": ["D","H","C"] }, { "name": "Jorah", "surname": "Mormont", "alive": false, "traits": ["A","B","C","F"] }, { "name": "Petyr", "surname": "Baelish", "alive": false, "traits": ["E","G","F"] }, { "name": "Viserys", "surname": "Targaryen", "alive": false, "traits": ["O","L","N"] }, { "name": "Jon", "surname": "Snow", "alive": true, "age": 16, "traits": ["A","B","C","F"] }, { "name": "Sansa", "surname": "Stark", "alive": true, "age": 13, "traits": ["D","I","J"] }, { "name": "Arya", "surname": "Stark", "alive": true, "age": 11, "traits": ["C","K","L"] }, { "name": "Robb", "surname": "Stark", "alive": false, "traits": ["A","B","C","K"] }, { "name": "Theon", "surname": "Greyjoy", "alive": true, "age": 16, "traits": ["E","R","K"] }, { "name": "Bran", "surname": "Stark", "alive": true, "age": 10, "traits": ["L","J"] }, { "name": "Joffrey", "surname": "Baratheon", "alive": false, "age": 19, "traits": ["I","L","O"] }, { "name": "Sandor", "surname": "Clegane", "alive": true, "traits": ["A","P","K","F"] }, { "name": "Tyrion", "surname": "Lannister", "alive": true, "age": 32, "traits": ["F","K","M","N"] }, { "name": "Khal", "surname": "Drogo", "alive": false, "traits": ["A","C","O","P"] }, { "name": "Tywin", "surname": "Lannister", "alive": false, "traits": ["O","M","H","F"] }, { "name": "Davos", "surname": "Seaworth", "alive": true, "age": 49, "traits": ["C","K","P","F"] }, { "name": "Samwell", "surname": "Tarly", "alive": true, "age": 17, "traits": ["C","L","I"] }, { "name": "Stannis", "surname": "Baratheon", "alive": false, "traits": ["H","O","P","M"] }, { "name": "Melisandre", "alive": true, "traits": ["G","E","H"] }, { "name": "Margaery", "surname": "Tyrell", "alive": false, "traits": ["M","D","B"] }, { "name": "Jeor", "surname": "Mormont", "alive": false, "traits": ["C","H","M","P"] }, { "name": "Bronn", "alive": true, "traits": ["K","E","C"] }, { "name": "Varys", "alive": true, "traits": ["M","F","N","E"] }, { "name": "Shae", "alive": false, "traits": ["M","D","G"] }, { "name": "Talisa", "surname": "Maegyr", "alive": false, "traits": ["D","C","B"] }, { "name": "Gendry", "alive": false, "traits": ["K","C","A"] }, { "name": "Ygritte", "alive": false, "traits": ["A","P","K"] }, { "name": "Tormund", "surname": "Giantsbane", "alive": true, "traits": ["C","P","A","I"] }, { "name": "Gilly", "alive": true, "traits": ["L","J"] }, { "name": "Brienne", "surname": "Tarth", "alive": true, "age": 32, "traits": ["P","C","A","K"] }, { "name": "Ramsay", "surname": "Bolton", "alive": true, "traits": ["E","O","G","A"] }, { "name": "Ellaria", "surname": "Sand", "alive": true, "traits": ["P","O","A","E"] }, { "name": "Daario", "surname": "Naharis", "alive": true, "traits": ["K","P","A"] }, { "name": "Missandei", "alive": true, "traits": ["D","L","C","M"] }, { "name": "Tommen", "surname": "Baratheon", "alive": true, "traits": ["I","L","B"] }, { "name": "Jaqen", "surname": "H'ghar", "alive": true, "traits": ["H","F","K"] }, { "name": "Roose", "surname": "Bolton", "alive": true, "traits": ["H","E","F","A"] }, { "name": "The High Sparrow", "alive": true, "traits": ["H","M","F","O"] } ] FOR d IN data INSERT d INTO Characters 复制代码
语法:
LET variableName = valueExpression
LET关键字定义了同名称的变量数据和对象值的数列,格式为 [ {...}, {...}, ... ]
FOR variableName IN expression
用于迭代数据数组的每个元素 。在每个循环中,将一个元素分配给变量d。然后在INSERT语句中使用此变量。相当于下面的格式:
INSERT { "name": "Robert", "surname": "Baratheon", "alive": false, "traits": ["A","H","C"] } INTO Characters INSERT { "name": "Jaime", "surname": "Lannister", "alive": true, "age": 36, "traits": ["A","F","B"] } INTO Characters ... 复制代码
检索
检索集合中的所有文档:
FOR c IN Characters RETURN c 复制代码
语法:
FOR variableName IN collectionName
对于集合中的每个文档,依次分配给变量c,然后根据循环体返回该文档。
选取其中一个文档如下:
{ "_key": "2861650", "_id": "Characters/2861650", "_rev": "_V1bzsXa---", "name": "Ned", "surname": "Stark", "alive": true, "age": 41, "traits": ["A","H","C","N","P"] }, 复制代码
该文档包含我们存储的四个属性,以及数据库系统添加的另外三个属性:
-
_key:文档键,用户可以在创建文档时提供文档键,也可以自动分配唯一值,不能改变,只读
-
_id:集合名/文档键,只读
-
_rev:系统管理的修订版ID,只读
检索特定文档:
RETURN DOCUMENT("Characters", "2861650") // --- or --- RETURN DOCUMENT("Characters/2861650") 复制代码
返回:
[ { "_key": "2861650", "_id": "Characters/2861650", "_rev": "_V1bzsXa---", "name": "Ned", "surname": "Stark", "alive": true, "age": 41, "traits": ["A","H","C","N","P"] } ] 复制代码
语法:
DOCUMENT()
使用_key或_id检索特定文档,该函数还允许一次获取多个文档
RETURN DOCUMENT("Characters", ["2861650", "2861653"]) // --- or --- RETURN DOCUMENT(["Characters/2861650", "Characters/2861653"]) 复制代码
更新文档:
修改现有文件:
UPDATE "2861650" WITH { alive: false } IN Characters 语法: UPDATE documentKey WITH object IN collectionName 复制代码
用列出的属性更新指定的文档(如果它们不存在则添加它们),但保持其余不变。要替换整个文档内容,则要使用REPLACE函数:
REPLACE "2861650" WITH { name: "Ned", surname: "Stark", alive: false, age: 41, traits: ["A","H","C","N","P"] } IN Characters 复制代码
该函数也适用于循环,例如为所有文档添加新属性:
FOR c IN Characters UPDATE c WITH { season: 1 } IN Characters 复制代码
删除文件:
语法:
REMOVE _key IN Collectiosname
要从集合中完全删除文档,需要执行REMOVE操作。它的工作方式与其他修改操作类似,但没有WITH子句:
REMOVE "2861650" IN Characters 复制代码
三、匹配文件
语法:
FILTER
查找满足比_key相等更复杂的条件的文档,能够为要匹配的文档制定任意条件。
等于条件:
FOR c IN Characters FILTER c.name == "Ned" RETURN c 复制代码
过滤条件如下:“ 字符文档的属性name必须等于字符串Ned ”。如果条件适用,则返回字符文档。
范围条件:
FOR c IN Characters FILTER c.age >= 13 RETURN c.name 复制代码
多种条件:
FOR c IN Characters FILTER c.age < 13 FILTER c.age != null RETURN { name: c.name, age: c.age } //or FOR c IN Characters FILTER c.age < 13 AND c.age != null RETURN { name: c.name, age: c.age } 复制代码
替代条件:
FOR c IN Characters FILTER c.name == "Jon" OR c.name == "Joffrey" RETURN { name: c.name, surname: c.surname } 复制代码
四、 排序 和限制
限制语法:
LIMIT()
LIMIT后面跟着一个最大显示数的数字,限制结果显示行数。
FOR c IN Characters LIMIT 5 RETURN c.name 复制代码
还可以使用LIMIT来跳过一定数量的记录返回下一个n个文档:
FOR c IN Characters LIMIT 2, 5 RETURN c.name 复制代码
排序语法:
SORT()
DESC降序来反转排序顺序
FOR c IN Characters SORT c.name DESC LIMIT 10 RETURN c.name 复制代码
多个字段排序
FOR c IN Characters FILTER c.surname SORT c.surname, c.name LIMIT 10 RETURN { surname: c.surname, name: c.name } 复制代码
此处FILTER的作用是仅保留surname为非空记录
五、组合
语法: MERGE()
MERGE()的功能是将对象组合在一起。因为使用了原始字符属性{ traits: ... },所以后者被合并覆盖。
FOR c IN Characters RETURN MERGE(c, { traits: DOCUMENT("Traits", c.traits)[*].en } ) 复制代码
六、图操作
创建图:
语法:
INSERT { _from: _id(A), _to: _id(B) } INTO ChildOf
实例: 首先,创建一个新的集合,并确保将集合类型更改为Edge。
然后,通过查询多个集合的数据,将结果存入边集合中
LET data = [ //关系数据 { "parent": { "name": "Ned", "surname": "Stark" }, "child": { "name": "Robb", "surname": "Stark" } }, { "parent": { "name": "Ned", "surname": "Stark" }, "child": { "name": "Sansa", "surname": "Stark" } }, { "parent": { "name": "Ned", "surname": "Stark" }, "child": { "name": "Arya", "surname": "Stark" } }, { "parent": { "name": "Ned", "surname": "Stark" }, "child": { "name": "Bran", "surname": "Stark" } }, { "parent": { "name": "Catelyn", "surname": "Stark" }, "child": { "name": "Robb", "surname": "Stark" } }, { "parent": { "name": "Catelyn", "surname": "Stark" }, "child": { "name": "Sansa", "surname": "Stark" } }, { "parent": { "name": "Catelyn", "surname": "Stark" }, "child": { "name": "Arya", "surname": "Stark" } }, { "parent": { "name": "Catelyn", "surname": "Stark" }, "child": { "name": "Bran", "surname": "Stark" } }, { "parent": { "name": "Ned", "surname": "Stark" }, "child": { "name": "Jon", "surname": "Snow" } }, { "parent": { "name": "Tywin", "surname": "Lannister" }, "child": { "name": "Jaime", "surname": "Lannister" } }, { "parent": { "name": "Tywin", "surname": "Lannister" }, "child": { "name": "Cersei", "surname": "Lannister" } }, { "parent": { "name": "Tywin", "surname": "Lannister" }, "child": { "name": "Tyrion", "surname": "Lannister" } }, { "parent": { "name": "Cersei", "surname": "Lannister" }, "child": { "name": "Joffrey", "surname": "Baratheon" } }, { "parent": { "name": "Jaime", "surname": "Lannister" }, "child": { "name": "Joffrey", "surname": "Baratheon" } } ] FOR rel in data LET parentId = FIRST( //FIRST()提取第一个元素 FOR c IN Characters FILTER c.name == rel.parent.name //筛选条件 FILTER c.surname == rel.parent.surname LIMIT 1 RETURN c._id //返回_id ) LET childId = FIRST( FOR c IN Characters FILTER c.name == rel.child.name FILTER c.surname == rel.child.surname LIMIT 1 RETURN c._id ) FILTER parentId != null AND childId != null //剔除_id都为空的记录 INSERT { _from: childId, _to: parentId } INTO ChildOf //将数据插入边集合 RETURN NEW //返回数据 复制代码
也可以直接创建边数据:
INSERT { _from: "Characters/robb", _to: "Characters/ned" } INTO ChildOf 复制代码
遍历图:
语法:
FOR v IN 1..1 OUTBOUND _id ChildOf RETURN v.name 其中1..1为遍历深度 复制代码
实例:
FOR c IN Characters FILTER c.name == "Bran" FOR v IN 1..1 OUTBOUND c ChildOf RETURN v.name 复制代码
返回
[ "Ned", "Catelyn" ] 复制代码
遍历的情况如下图:
若是反向遍历,则需要使用到INBOUND关键字:
FOR c IN Characters FILTER c.name == "Tywin" FOR v IN 2..2 INBOUND c ChildOf RETURN DISTINCT v.name 输出: [ "Joffrey" ] 复制代码
遍历情况如下:
需要注意的是,“1..1”限制了遍历深度为1,“2..2”限制了遍历深度为2,而"1..2"限制遍历深度既可以为1也可以为2。
七、地理空间查询
地点数据
创建地点集合:
录入地点数据:
LET places = [ { "name": "Dragonstone", "coordinate": [ 55.167801, -6.815096 ] }, { "name": "King's Landing", "coordinate": [ 42.639752, 18.110189 ] }, { "name": "The Red Keep", "coordinate": [ 35.896447, 14.446442 ] }, { "name": "Yunkai", "coordinate": [ 31.046642, -7.129532 ] }, { "name": "Astapor", "coordinate": [ 31.50974, -9.774249 ] }, { "name": "Winterfell", "coordinate": [ 54.368321, -5.581312 ] }, { "name": "Vaes Dothrak", "coordinate": [ 54.16776, -6.096125 ] }, { "name": "Beyond the wall", "coordinate": [ 64.265473, -21.094093 ] } ] FOR place IN places INSERT place INTO Locations 复制代码
设置地理空间索引:
在COLLECTIONS界面,添加新的Indexes,设置为coordinate字段:
查找附近的位置
语法:
NEAR()
找到最接近的坐标参考点
FOR loc IN NEAR(Locations, 53.35, -6.26, 3) RETURN { name: loc.name, latitude: loc.coordinate[0], longitude: loc.coordinate[1] } 复制代码
输出:
[ { "name": "Vaes Dothrak", "latitude": 54.16776, "longitude": -6.096125 }, { "name": "Winterfell", "latitude": 54.368321, "longitude": -5.581312 }, { "name": "Dragonstone", "latitude": 55.167801, "longitude": -6.815096 } ] 复制代码
查找半径内的位置
语法:
WITHIN()
从参考点搜索给定半径内的位置
FOR loc IN WITHIN(Locations, 53.35, -6.26, 200 * 1000) RETURN { name: loc.name, latitude: loc.coordinate[0], longitude: loc.coordinate[1] } 复制代码
输出
[ { "name": "Vaes Dothrak", "latitude": 54.16776, "longitude": -6.096125 }, { "name": "Winterfell", "latitude": 54.368321, "longitude": -5.581312 } ] 复制代码
按距离查找位置:
语法:
NEAR()或WITHIN()
通过添加一个可选的第五个参数返回到参考点的距离。必须是一个字符串:
FOR loc IN NEAR(Locations, 53.35, -6.26, 3, "distance") RETURN { name: loc.name, latitude: loc.coordinate[0], longitude: loc.coordinate[1], distance: loc.distance / 1000 } 复制代码
输出:
[ { "name": "Vaes Dothrak", "latitude": 54.16776, "longitude": -6.096125, "distance": 91.56658640314431 }, { "name": "Winterfell", "latitude": 54.368321, "longitude": -5.581312, "distance": 121.66399816395028 }, { "name": "Dragonstone", "latitude": 55.167801, "longitude": -6.815096, "distance": 205.31879386198324 } ] 复制代码
以上所述就是小编给大家介绍的《ArangoDB查询语言(AQL) 基本语法&用法》,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对 码农网 的支持!
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