项目 6 数据存储：仿冒 SqlClient（T-SQL 转写成 SQLite）、数据库页面、DataGridView、DateTimePicker
- 每个学生一套数据库，长期保存（data/databases/<用户编号>/库名.db）；学生程序运行时挂进沙箱可读写 - Sim.Data：SqlConnection / SqlCommand / SqlDataReader / SqlDataAdapter / SqlCommandBuilder / SqlParameter； 连接字符串只按库名打开学生自己的库；ScriptDom 解析 T-SQL 后按白名单转写成 SQLite 语句， STRICT 表 + 元数据表还原 SQL Server 的列类型，报错编号和中文信息与 SQL Server 一致； INSERT 不写列名时跳过自增列，日期统一格式（书上 DateTime.ToString() 拼接的日期能正确比较） - 常驻 SQL 服务（Sim.Runner sql-server）：数据库页面的查询、对象资源管理器，评分前按实验 database.sql 建库 - 数据库页面（代替 SSMS）：对象资源管理器、查询窗口、编辑前 200 行、表设计器、恢复实验初始数据 - DataGridView（绑定 DataView/DataTable/DataSet，单元格修改写回 DataTable）、DateTimePicker；设计器工具箱加入 - 评分：每个检查项一份新建的实验库；新增点 / 修改表格单元格、选日期、表格里有 / 没有某行的检查 - 示例：项目 6 任务 2、3；时间格式改成和中文 Windows 一致（9:05:03）；异常堆栈不暴露服务器路径 - 测试：数据库端到端、接口（每人只看到自己的库、恢复实验数据）、评分出错情况、T-SQL 生成 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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using System;
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using System.Collections.Generic;
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using System.Data.SqlClient;
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using System.IO;
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using System.Linq;
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using Microsoft.Data.Sqlite;
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namespace Sim.Data.Engine;
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/// <summary>一列的定义（来自元数据表，保留建表时的 T-SQL 写法）</summary>
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internal sealed record ColumnInfo(string Name, TSqlType Type, bool Nullable, bool Identity, bool PrimaryKey, string? Default);
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internal sealed record TableInfo(string Name, IReadOnlyList<ColumnInfo> Columns)
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{
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public ColumnInfo? Find(string column) => Columns.FirstOrDefault(c => string.Equals(c.Name, column, StringComparison.OrdinalIgnoreCase));
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public ColumnInfo? Identity => Columns.FirstOrDefault(c => c.Identity);
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}
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/// <summary>
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/// 一个学生的全部数据库：一个目录，每个库一个 SQLite 文件（库名.db）。
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/// master 是默认库（连接字符串里不写 Initial Catalog 时连到它），和 SQL Server 一样也能在里面建表。
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/// </summary>
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internal sealed class DatabaseStore
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{
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public const string Master = "master";
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/// <summary>元数据表：每列的 T-SQL 类型、是否自增等。学生的 SQL 里不能引用它</summary>
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public const string MetaTable = "__sim_columns";
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private const int MaxDatabases = 20;
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/// <summary>每个库最多约 50 MB（4 KB 一页）</summary>
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private const int MaxPages = 12800;
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public DatabaseStore(string directory) => Directory = directory;
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public string Directory { get; }
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/// <summary>学生程序运行时：服务器通过环境变量 SIM_DB_DIR 指定（沙箱里挂载学生自己的数据库目录）</summary>
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public static DatabaseStore? FromEnvironment() =>
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Environment.GetEnvironmentVariable("SIM_DB_DIR") is { Length: > 0 } dir ? new DatabaseStore(dir) : null;
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public IEnumerable<string> List() =>
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System.IO.Directory.Exists(Directory)
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? System.IO.Directory.EnumerateFiles(Directory, "*.db").Select(f => Path.GetFileNameWithoutExtension(f)!).Where(n => n != Master).Order(StringComparer.Ordinal)
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: Enumerable.Empty<string>();
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/// <summary>库名大小写不敏感（和 SQL Server 一样），返回磁盘上实际的名字</summary>
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public string? Resolve(string name)
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{
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if (string.Equals(name, Master, StringComparison.OrdinalIgnoreCase)) return Master;
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return List().FirstOrDefault(n => string.Equals(n, name, StringComparison.OrdinalIgnoreCase));
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}
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public SqliteConnection Open(string name)
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{
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var resolved = Resolve(name);
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if (resolved == null) throw SqlException.CannotOpenDatabase(name);
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if (resolved == Master && !File.Exists(PathOf(Master))) Create(Master, allowMaster: true);
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// 不用连接池：最后一个连接关闭时 WAL 里的数据写回主文件，复制、恢复数据库文件时不会丢数据
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var connection = new SqliteConnection(new SqliteConnectionStringBuilder { DataSource = PathOf(resolved), Mode = SqliteOpenMode.ReadWrite, Pooling = false }.ToString());
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connection.Open();
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Functions.Register(connection);
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using var pragma = connection.CreateCommand();
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pragma.CommandText = $"PRAGMA max_page_count = {MaxPages}; PRAGMA case_sensitive_like = OFF;";
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pragma.ExecuteNonQuery();
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return connection;
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}
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public void Create(string name, bool allowMaster = false)
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{
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CheckName(name);
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if (!allowMaster && Resolve(name) != null) throw SqlException.DatabaseExists(name);
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if (List().Count() >= MaxDatabases) throw new SqlException(1105, $"最多只能建 {MaxDatabases} 个数据库，先删除不用的数据库。");
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System.IO.Directory.CreateDirectory(Directory);
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using var connection = new SqliteConnection(new SqliteConnectionStringBuilder { DataSource = PathOf(name), Mode = SqliteOpenMode.ReadWriteCreate, Pooling = false }.ToString());
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connection.Open();
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using var command = connection.CreateCommand();
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command.CommandText =
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"PRAGMA journal_mode = WAL;" +
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$"CREATE TABLE IF NOT EXISTS {MetaTable} (table_name TEXT NOT NULL COLLATE NOCASE, column_name TEXT NOT NULL COLLATE NOCASE, " +
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"ordinal INTEGER NOT NULL, type_name TEXT NOT NULL, nullable INTEGER NOT NULL, is_identity INTEGER NOT NULL, " +
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"is_primary_key INTEGER NOT NULL, default_text TEXT, PRIMARY KEY (table_name, column_name));";
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command.ExecuteNonQuery();
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}
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public void Drop(string name)
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{
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var resolved = Resolve(name);
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if (resolved == null || resolved == Master) throw new SqlException(3701, $"无法对 数据库 '{name}' 执行 删除，因为它不存在，或者您没有所需的权限。");
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foreach (var suffix in new[] { "", "-wal", "-shm" }) File.Delete(PathOf(resolved) + suffix);
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}
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private string PathOf(string name) => Path.Combine(Directory, name + ".db");
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/// <summary>库名就是文件名：不能有路径分隔符等字符</summary>
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private static void CheckName(string name)
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{
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if (name.Length is 0 or > 64 || name.StartsWith('.') || name.IndexOfAny(Path.GetInvalidFileNameChars()) >= 0 || name.IndexOfAny(['\\', ':', '*', '?', '"', '<', '>', '|']) >= 0)
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throw new SqlException(102, $"数据库名 '{name}' 无效：不能为空、不能超过 64 个字，也不能包含 \\ / : * ? \" < > | 等字符。");
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}
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// ---------- 表结构（元数据表） ----------
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public static TableInfo? GetTable(SqliteConnection connection, string name)
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{
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if (IsHidden(name)) return null;
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using var command = connection.CreateCommand();
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command.CommandText = "SELECT name FROM sqlite_master WHERE type = 'table' AND name = $name COLLATE NOCASE";
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command.Parameters.AddWithValue("$name", name);
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if (command.ExecuteScalar() is not string actual) return null;
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command.CommandText = $"SELECT column_name, type_name, nullable, is_identity, is_primary_key, default_text FROM {MetaTable} WHERE table_name = $name ORDER BY ordinal";
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var columns = new List<ColumnInfo>();
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using (var reader = command.ExecuteReader())
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{
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while (reader.Read())
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{
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columns.Add(new ColumnInfo(reader.GetString(0), TSqlType.Parse(reader.GetString(1)), reader.GetInt64(2) != 0,
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reader.GetInt64(3) != 0, reader.GetInt64(4) != 0, reader.IsDBNull(5) ? null : reader.GetString(5)));
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}
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}
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return new TableInfo(actual, columns);
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}
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public static IReadOnlyList<string> ListTables(SqliteConnection connection)
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{
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using var command = connection.CreateCommand();
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command.CommandText = "SELECT name FROM sqlite_master WHERE type = 'table' ORDER BY name";
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var tables = new List<string>();
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using var reader = command.ExecuteReader();
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while (reader.Read())
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{
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var name = reader.GetString(0);
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if (!IsHidden(name)) tables.Add(name);
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}
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return tables;
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}
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public static void SaveColumns(SqliteConnection connection, string table, IEnumerable<ColumnInfo> columns, int firstOrdinal = 0)
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{
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using var command = connection.CreateCommand();
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command.CommandText = $"INSERT OR REPLACE INTO {MetaTable} VALUES ($t, $c, $o, $type, $null, $id, $pk, $def)";
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var ordinal = firstOrdinal;
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foreach (var column in columns)
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{
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command.Parameters.Clear();
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command.Parameters.AddWithValue("$t", table);
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command.Parameters.AddWithValue("$c", column.Name);
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command.Parameters.AddWithValue("$o", ordinal++);
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command.Parameters.AddWithValue("$type", column.Type.ToString());
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command.Parameters.AddWithValue("$null", column.Nullable ? 1 : 0);
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command.Parameters.AddWithValue("$id", column.Identity ? 1 : 0);
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command.Parameters.AddWithValue("$pk", column.PrimaryKey ? 1 : 0);
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command.Parameters.AddWithValue("$def", (object?)column.Default ?? DBNull.Value);
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command.ExecuteNonQuery();
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}
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}
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public static void DeleteColumns(SqliteConnection connection, string table)
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{
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using var command = connection.CreateCommand();
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command.CommandText = $"DELETE FROM {MetaTable} WHERE table_name = $t";
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command.Parameters.AddWithValue("$t", table);
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command.ExecuteNonQuery();
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}
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/// <summary>平台内部的表和 SQLite 系统表，学生看不到也不能引用</summary>
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public static bool IsHidden(string name) =>
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name.StartsWith("__sim", StringComparison.OrdinalIgnoreCase) || name.StartsWith("sqlite_", StringComparison.OrdinalIgnoreCase);
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}
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