LinqDB数据库查询数据，还是很方便的。
1. 添加Entity数据实体类
方便之后映射操作
1 /// <summary>
2 /// 课件
3 /// </summary>
4 [DataContract]
5 [Table("Courseware")]
6 public class CoursewareInfo
7 {
8 [DataMember(Name = "LocalId")]
9 [PrimaryKey, Column("LocalId"), NotNull]
10 public string LocalId { get; set; }
11
12 [DataMember(Name = "RemoteId")]
13 [Column("RemoteId")]
14 public string RemoteId { get; set; }
15
16 [Column("Name")]
17 public string Name { get; set; }
18
2. 添加DB操作通用类
1 public class DbProvider<TDB> where TDB : LinqToDB.Data.DataConnection, new()
2 {
3 private readonly string _connectionString;
4 private readonly Func<string> _getConnectionStringFunc;
5
6 private string ConnectionString
7 => string.IsNullOrEmpty(_connectionString) ? _getConnectionStringFunc() : _connectionString;
8
9 public DbProvider(Func<string> getConnectionStringFunc)
10 {
11 _getConnectionStringFunc = getConnectionStringFunc;
12 }
13 public TReturn Execute<TReturn>(Func<TDB, TReturn> execute)
14 {
15 TDB db = null;
16 try
17 {
18 db = (TDB)Activator.CreateInstance(typeof(TDB), new SQLiteDataProvider(), ConnectionString);
19 return execute(db);
20 }
21 catch (Exception ex)
22 {
23 return default(TReturn);
24 }
25 finally
26 {
27 db?.Dispose();
28 }
29 }
30
3. 添加指定数据库的映射连接类
1 public partial class CoursewareInfoDb : DataConnection
2 {
3 public ITable<CoursewareInfo> Coursewares => GetTable<CoursewareInfo>();
4
5 public CoursewareInfoDb()
6 {
7 InitDataContext();
8 }
9
10 public CoursewareInfoDb(string configuration)
11 : base(configuration)
12 {
13 InitDataContext();
14 }
15
16 public CoursewareInfoDb(IDataProvider dataProvider, string connectionString)
17 : base(dataProvider, connectionString)
18 {
19 InitDataContext();
20 }
21
22 partial void InitDataContext();
23
4. 添加数据库查询辅助类
这里是将数据库放在程序启动目录下，通过绝对路径引用。
1 public class CoursewareSqliteDataReader
2 {
3 private static readonly string DbName = "CoursewareCacheData.db";
4 private readonly DbProvider<CoursewareInfoDb> _coursewareDbProvider;
5
6 public CoursewareSqliteDataReader()
7 {
8 var dbPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, $"Dbs\\{DbName}");
9
10 if (!File.Exists(dbPath))
11 {
12 throw new InvalidOperationException("路径下不存在数据库文件");
13 }
14 _coursewareDbProvider = new DbProvider<CoursewareInfoDb>(() => $"Data Source={dbPath}");
15 }
16
17 public List<CoursewareInfo> GetCoursewares()
18 {
19 return _coursewareDbProvider.Execute(db => db.Coursewares.ToList());
20 }
21 public List<CoursewareInfo> GetCoursewares(string queryText)
22 {
23 return _coursewareDbProvider.Execute(db => db.Coursewares.Where(i=>i.Name.Contains(queryText)).ToList());
24 }
25
作者：唐宋元明清2188
