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What is the difference between id and class in CSS, and when should I use them? [duplicate]
Here I gave an id to the div element and it's applying the relevant CSS for it.
15 Answers
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How do I find a “gap” in running counter with SQL?
I'd like to find the first "gap" in a counter column in an SQL table. For example, if there are values 1,2,4 and 5 I'd like to find out 3.
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MySQL foreign key constraints, cascade delete
I want to use foreign keys to keep the integrity and avoid orphans (I already use innoDB).
3 Answers
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Can an html element have multiple ids?
I understand that an id must be unique within an HTML/XHTML page.
18 Answers
18
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Grouped LIMIT in PostgreSQL: show the first N rows for each group?
... edited Aug 11 '16 at 9:08
ngspkinga
42155 silver badges1616 bronze badges
answered May 19 '11 at 19:55
DaveDa...
How to efficiently build a tree from a flat structure?
I have a bunch of objects in a flat structure. These objects have an ID and a ParentID property so they can be arranged in trees. They are in no particular order.
Each ParentID property does not necessarily matches with an ID in the structure. Therefore their could be several trees emerging ...
mongodb group values by multiple fields
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TLDR Summary
In modern MongoDB releases you can brute force this with $slice just off the basic aggregation result. For "large" results, run parallel queries instead for each grouping ( a demonstration listing is at the end of the answer ...
mongodb/mongoose findMany - find all documents with IDs listed in array
I have an array of _ids and I want to get all docs accordingly, what's the best way to do it ?
5 Answers
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Real life example, when to use OUTER / CROSS APPLY in SQL
I have been looking at CROSS / OUTER APPLY with a colleague and we're struggling to find real life examples of where to use them.
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Stop Mongoose from creating _id property for sub-document array items
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It's simple, you can define this in the subschema :
var mongoose = require("mongoose");
var subSchema = mongoose.Schema({
//your subschema content
},{ _id : false });
var schema = mongoose.Schema({
// schema content
subSchemaCollectio...