[NoSQL]基本コードの実装

Select * from emplyees where empno=7369

db.employees.find({empno:7369})

{ "_id": "E1", "empno": 7369, "ename": "SMITH", "job": "CLERK", "hiredate": "17-12-1980", "sal": 800, "deptno": 20 }
Select ename from emlpoyees where empno=7900

db.employees.find({empno:7900}, {ename:1})

{ "_id": "E2", "ename": "JAMES"}
Select empno, ename from employees where empno > 7500 and empno <=7600

db.employees.find({empno:{$gt:7500, $lte:7600}}, {empno:1, ename:1, _id:0})

{ "empno": 7566, "ename": "JONES"}
{ "empno": 7521, "ename": "WARD"}
Select empno from employees where empno = 7782 or empno=7844

db.employees.find($or:[{empno:7782}, {empno:7844}]}, {empno:1, _id:0})

{ "empno": 7782 }
{ "empno": 7844 }
Select count(*) from employees

db.employees.count()

14
Select count(*) from employees where empno > 7900
方法.

db.employees.find({empno:{$gt:7900}}).count()

2
方法.

db.employees.count({empno:{$gt:7900}})

2
Select distinct deptno from employees

db.employees.distinct("deptno")

[ 10, 20, 30 ]
Select ename, job from employees where deptno=10 prder by ename desc

db.employees.find({deptno:10}, {ename:1, job:1, _id:0}).sort({ename:-1})

{ "ename": "PRESIDENT", "job": "CEO"}
{ "ename": "CLERK", "job": "CLERK"}
{ "ename": "CLARK", "job": "MANAGER"}
Select sum(salary) from employees

db.employees.aggregate([ $group: {_id:null, total_salary: {$sum: "$sal"}}}])

{ "_id": null, "total_salary": 29025 }
Select deptno, avg(salary) from employees group by deptno order by deptno

db.employees.aggregate([{ $group: {_id: "$deptno", avg_sal: {$avg:"$sal"}}}, {$sort: {_id:1}}])

{ "_id": 10, "avg_sal": 2916.6666666666665 }
{ "_id": 10, "avg_sal": 2175 }
{ "_id": 10, "avg_sal": 1566.6666666666667 }