Difference between revisions of "MongoDB QueryData"
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Since version 2.2 MongoDB's new $elemMatch can avoid this: | Since version 2.2 MongoDB's new $elemMatch can avoid this: | ||
| − | db.deptCollection.find({" | + | db.deptCollection.find({"deptno":20}, |
| − | + | { _id: 0, employees: {$elemMatch: {empno: 7902}}}).pretty() | |
$elemMatch limits the contents of the employees array to contain only the first element matching the $elemMatch condition. | $elemMatch limits the contents of the employees array to contain only the first element matching the $elemMatch condition. | ||
Revision as of 21:00, 18 October 2016
Show all data so far:
db.deptCollection.find()
Comes back messy, can make it better:
db.deptCollection.find().pretty()
Or just find one document:
db.deptCollection.find({"deptno":10}).pretty()
Finding an employee means using the array name too:
db.deptCollection.find({"employees.empno":7902}).pretty()
However, does mean you get back all the employees!
Since version 2.2 MongoDB's new $elemMatch can avoid this:
db.deptCollection.find({"deptno":20},
{ _id: 0, employees: {$elemMatch: {empno: 7902}}}).pretty()
$elemMatch limits the contents of the employees array to contain only the first element matching the $elemMatch condition.
