基本查詢語句
db.selection_product_latest.insert({
name: 'zhangsan',
age: 5
})
db.selection_product_latest.find({
"title": "MongoDB Overview"
}).pretty();
db.selection_product_latest.find({
"likes": {
"$gte": 3000
}
}).pretty();
db.inventory.find( { 'instock.qty': { $lte: 20 },'instock.warehouse': "A" } )
db.inventory.find( { "instock": { $elemMatch: { qty: { $gte: 5, $lte: 20 }, warehouse: "A" } } } )
db.selection_product_latest.find().skip(1).limit(10)
db.selection_product_latest.aggregate([{$project:{"description":1}},{$group:{_id:"$title",sumLike:{"$sum":"$likes"}}}])
db.selection_product_latest.aggregate([{$skip:5},{$limit:10},{$group:{_id:"$title"}}])
db.selection_product_latest.aggregate([{$skip:5},{$limit:10},{$group:{_id:"$title",first_description:{$first : "$description"}}}])
db.selection_product_latest.aggregate([{$group:{_id:"$name",first_description:{$first : "$age"}}},{$sort:{"age":1}}]) //排序無效
db.selection_product_latest.aggregate([{ $match : { age : { $gte : 1, $lte : 90 } } },{$sort:{age:1}},{$group:{_id:"$name",first_description:{$first : "$age"}}},{$sort:{age:1}}])//排序有效
mongoDB踩過的坑
db.selection_product_latest.aggregate([{$skip:5},{$limit:10},{$group:{_id:"$title",first_description:{$first : "$description"}}}])//聚合后分頁無效
db.selection_product_latest.aggregate([{$group:{_id:"$title",first_description:{$first : "$description"}},{$skip:5},{$limit:10}}])//聚合后分頁有效
深度反省
Mongo和Mysql有很大的本質(zhì)區(qū)別曹阔，mongo像執(zhí)行代碼一樣只冻，執(zhí)行的順序?qū)Y(jié)果產(chǎn)生很大的影響呛讲。
