MongoDB queries suna amfani da operators (waɗanda suke farawa da $) don bayyana yanayi wanda ya fi sauƙi kawai — alinƙira, ilimin hankali, ilimin abin, da array operators. Waɗannan su ne abin gida na saƙar zai gyara jinjinaye don samun bayanai da kake bukata.
db..({ : { : } });
db..({ : { : , : } });
db..({ : { : } });
db..({ : { : [, ] } });
db..({ : { : [] } });
$eq $ne → equal / not equal
$gt $gte → greater than / greater-or-equal
$lt $lte → less than / less-or-equal
$in $nin → in / not in a list of values
// $and / $or / $not / $nor combine conditions
db.users.find({ $or: [{ age: { $lt: 18 } }, { age: { $gt: 65 } }] }); // young OR old
db.users.find({ $and: [{ active: true }, { premium: true }] });
// (multiple fields in one filter are AND by default)
db.users.find({ active: true, age: { $gt: 18 } }); // active AND age > 18
Alubosa da yawa a cikin sanarwa suna amfani da kalmomi gida ta AND; $or/$and/$not suna bayyana ilimin hankali mai wuyya.
db.users.find({ email: { $exists: true } }); // field exists
db.users.find({ age: { $type: "number" } }); // field is of a type
// array operators
db.posts.find({ tags: "mongodb" }); // array CONTAINS "mongodb"
db.posts.find({ tags: { $all: ["a", "b"] } }); // contains ALL of these
db.posts.find({ tags: { $size: 3 } }); // array has exactly 3 elements
db.posts.find({ "scores": { $elemMatch: { $gt: 80, $lt: 90 } } }); // an element matching
Array operators suna iyar jinjina a cikin arrays — $all (kasar duka), $size (tsayi), $elemMatch (wani abin da ya saba da yanayi da yawa), da daidaita ƙima a takaice yana bincika ɗamowa.
db.users.find({ "address.city": "NY" }); // query a NESTED field with dot notation
Query operators sune mahimmanci don ciyar da bayanai cikin kyau a MongoDB — neman takaɗɗi na takaɗɗi bisa ga yanayi shine abin da kake fa'i koyaushe a aikace-aikacen duka, saboda haka fahimta su ita ce ilimin mahimmanci na yau da kullun.
Sanin alinƙira operators ($gt, $lt, $in, da sauransu don keɓewa da daidaita ƙima), ilimin hankali operators ($or, $and, da cewa filayen da yawa a sanarwa suna amfani da kalmomi gida ta AND), ilimin abin operators ($exists, $type), da musamman array operators ($all, $size, $elemMatch, da daidaita ɗamowa kai tsaye) yana ɗauki jigon yanayi duka na jinjina da kake bukatar.
Array operators sune mahimmanci cikin gida a MongoDB saboda takadduntan abubuwan yawan kunna arrays (wani bangare mahimmanci na model na takaɗɗi), da iyar jinjina a cikin su (ɗamowa, dukan abubuwa, iyar jinjina abin) shine abin da ke gudana koyaushe wanda ke bambanta jinjina MongoDB.
Fahimta dot notation don iyar jinjina filayen da ke nesa ("address.city") ita ce mahimmanci kuma saboda fensir na MongoDB ke da tsarin nesa.
Tun jiyya ciyar da bayanai ita ce ɗaya daga cikin ayyukan banaji da ke fa'i koyaushe, da tun jiyya query operators na MongoDB (alinƙira, ilimin hankali, ilimin abin, musamman array operators, da nesa-filayen jinjina) sune hanyar da kake bayyana yanayi don samun takaddun takaɗɗi, fahimta query operators ita ce mahimmanci, abubuwan da ke fa'i koyaushe na ilimin MongoDB — daidai da fasaha ta SQL WHERE yanayi, da wajibi don rubuta jinjine masu ƙarfi a zangagal MongoDB zaren bayanai da array-mai yawa, abubuwan mahimmanci ga duk wanda ke haɗa MongoDB.