From: 011netservice@gmail.com
Date: 2023-06-22
Subject: readme-LiteDB.txt

歡迎來信交流, 訂購軟體需求.

#### Summary

□ github: https://github.com/mbdavid/LiteDB
□ 官網: https://www.litedb.org/
□ 安裝: 
  https://www.nuget.org/packages/LiteDB
  dotnet add package LiteDB --version 5.0.16
  最後一版為 5.0.16, 2023-03-10
  
□ 
LiteDB is a small, fast and lightweight .NET NoSQL embedded database.

Serverless NoSQL Document Store
Simple API, similar to MongoDB
100% C# code for .NET 4.5 / NETStandard 1.3/2.0 in a single DLL (less than 450kb)
Thread-safe
ACID with full transaction support
Data recovery after write failure (WAL log file)
Datafile encryption using DES (AES) cryptography
Map your POCO classes to BsonDocument using attributes or fluent mapper API
Store files and stream data (like GridFS in MongoDB)
Single data file storage (like SQLite)
Index document fields for fast search
LINQ support for queries
SQL-Like commands to access/transform data
LiteDB Studio - Nice UI for data access
Open source and free for everyone - including commercial use
Install from NuGet: Install-Package LiteDB
  
□
.每一資料庫實體檔案上限為 long.MaxValue = 9,223,372,036,854,775,807 bytes = 9,223,372 TB  
.可存放於memory中, 或實體檔案.
.每一筆 document 上限為 1MB, 若要存檔案在 document 欄位中, 則可使用 FileStorage.
.每一資料庫可放 8000 bytes 的 Collections 名稱. 例如, 若每一 Collection 名稱為 10 bytes, 則可放 800 個 Collections.
.等待鎖定共用資源預設 60 秒.
.Runtime reference:
  net45
  netstandard 1.3
  netstandard 2.0
  
  
#### How to use LiteDB
□
A quick example for storing and searching documents:

// Create your POCO class
public class Customer
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
    public string[] Phones { get; set; }
    public bool IsActive { get; set; }
}

// Open database (or create if doesn't exist)
using(var db = new LiteDatabase(@"MyData.db"))
{
    // Get customer collection
    var col = db.GetCollection<Customer>("customers");

    // Create your new customer instance
    var customer = new Customer
    { 
        Name = "John Doe", 
        Phones = new string[] { "8000-0000", "9000-0000" }, 
        Age = 39,
        IsActive = true
    };

    // Create unique index in Name field
    col.EnsureIndex(x => x.Name, true);

    // Insert new customer document (Id will be auto-incremented)
    col.Insert(customer);

    // Update a document inside a collection
    customer.Name = "Joana Doe";

    col.Update(customer);

    // Use LINQ to query documents (with no index)
    var results = col.Find(x => x.Age > 20);
}

□
Using fluent mapper and cross document reference for more complex data models

// DbRef to cross references
public class Order
{
    public ObjectId Id { get; set; }
    public DateTime OrderDate { get; set; }
    public Address ShippingAddress { get; set; }
    public Customer Customer { get; set; }
    public List<Product> Products { get; set; }
}        

// Re-use mapper from global instance
var mapper = BsonMapper.Global;

// "Products" and "Customer" are from other collections (not embedded document)
mapper.Entity<Order>()
    .DbRef(x => x.Customer, "customers")   // 1 to 1/0 reference
    .DbRef(x => x.Products, "products")    // 1 to Many reference
    .Field(x => x.ShippingAddress, "addr"); // Embedded sub document
            
using(var db = new LiteDatabase("MyOrderDatafile.db"))
{
    var orders = db.GetCollection<Order>("orders");
        
    // When query Order, includes references
    var query = orders
        .Include(x => x.Customer)
        .Include(x => x.Products) // 1 to many reference
        .Find(x => x.OrderDate <= DateTime.Now);

    // Each instance of Order will load Customer/Products references
    foreach(var order in query)
    {
        var name = order.Customer.Name;
        ...
    }
}