大约有 47,000 项符合查询结果（耗时：0.0400秒） [XML]
How to get duplicate items from a list using LINQ? [duplicate]
...
var duplicates = lst.GroupBy(s => s)
.SelectMany(grp => grp.Skip(1));
Note that this will return all duplicates, so if you only want to know which items are duplicated in the source list, you could apply Distinct to the resulting sequence or use the solution...
How to set conditional breakpoints in Visual Studio?
...t a breakpoint.
Right-Click over the breakpoint, and in the popup menu you select an option that suites you.
These options are as follows:
You can set a condition, based on a code expression that you supply (select Condition from the popup menu). For instance, you can specify that foo == 8 or s...
Sorting rows in a data table
...
Its Simple Use .Select function.
DataRow[] foundRows=table.Select("Date = '1/31/1979' or OrderID = 2", "CompanyName ASC");
DataTable dt = foundRows.CopyToDataTable();
And it's done......Happy Coding
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MongoDB Show all contents from all collections
...
Step 1: See all your databases:
show dbs
Step 2: Select the database
use your_database_name
Step 3: Show the collections
show collections
This will list all the collections in your selected database.
Step 4: See all the data
db.collection_name.find()
or
db.colle...
How to get the insert ID in JDBC?
...or Oracle, you can invoke a CallableStatement with a RETURNING clause or a SELECT CURRVAL(sequencename) (or whatever DB-specific syntax to do so) directly after the INSERT in the same transaction to obtain the last generated key. See also this answer.
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Why does String.valueOf(null) throw a NullPointerException?
...s
How does polymorph ambiguity distinction work?
Which overload will get selected for null in Java?
Moral of the story
There are several important ones:
Effective Java 2nd Edition, Item 41: Use overloading judiciously
Just because you can overload, doesn't mean you should every time
They ...
What does each of the [y,n,q,a,d,/,K,j,J,g,e,?] stand for in context of git -p
...lowing
patch
This lets you choose one path out of a status like selection. After choosing the path, it presents the diff between the index and the working tree file and asks you if you want to stage the change of each hunk. You can select one of the following options and type return:
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Recommended SQL database design for tags or tagging [closed]
...ries which you will do: Output all Tags for one Item, draw a Tag-Cloud and select all items for one Tag Title.
All Tags for one Item:
3-Table:
SELECT Tag.Title
FROM Tag
JOIN ItemTag ON Tag.TagID = ItemTag.TagID
WHERE ItemTag.ItemID = :id
2-Table:
SELECT Tag.Title
FROM Tag
WHERE Tag.Item...
ActiveRecord OR query
...here(t[:author].eq("Someone").or(t[:title].matches("%something%"))).to_sql
SELECT "posts".* FROM "posts" WHERE (("posts"."author" = 'Someone' OR "posts"."title" LIKE '%something%'))
share
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Is there a query language for JSON?
...joined items
.equals("location.state", "TX")
//and even do custom selections
.select(function(rec) {
return {
fullname : rec.firstname + " " + rec.lastname,
city : rec.location.city,
ageInTenYears : (rec.age + 10)
};
});
It's ful...