Query Language Snippets
All Snippets
MongoDB
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Use $project to reshape output documents.
db.users.aggregate([
{ $project: { name: 1, age: 1, _id: 0 } }
]);
MongoDB
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Use distinct to find unique values for a field.
db.users.distinct("city");
MongoDB
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Use text search with $text operator.
db.articles.createIndex({ content: "text" });
db.articles.find({ $text: { $search: "mongodb aggregation" } });
Redis
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Get a value by key.
GET user:1:name
Redis
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Search for documents with RediSearch (exact match).
FT.SEARCH users_idx "@name:Alice"
Redis
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Search for documents with RediSearch (range).
FT.SEARCH users_idx "@age:[21 30]"
Redis
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Search for documents with RediSearch (prefix).
FT.SEARCH users_idx "@name:jo*"
SQLAlchemy
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Query records with a filter using SQLAlchemy.
users = session.query(User).filter(User.age > 25).all()
for user in users:
print(user.name, user.age)
Django ORM
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Django ORM select_related for foreign key optimization.
users = User.objects.select_related('profile').all()
for user in users:
print(user.profile.bio)
Django ORM
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Django ORM prefetch_related for many-to-many optimization.
users = User.objects.prefetch_related('groups').all()
for user in users:
print([group.name for group in user.groups.all()])
Django ORM
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Django ORM aggregate and annotate.
from django.db.models import Count, Avg
users = User.objects.values('department').annotate(Count('id'), avg_age=Avg('age'))
for u in users:
print(u['department'], u['id__count'], u['avg_age'])
Django ORM
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Django ORM F() expressions for field references.
from django.db.models import F
User.objects.filter(age__gt=F('min_age') * 2)