271 lines
9.9 KiB
C#
271 lines
9.9 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Data;
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using System.Data.SQLite;
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namespace Ramitta
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{
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public class SQLite : IDisposable
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{
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private SQLiteConnection db;
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private bool disposed = false;
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// 构造函数，初始化数据库连接
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// 参数: connectionString - 数据库连接字符串
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// 例如: "Data Source=mydatabase.db;Version=3;"
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public SQLite(string connectionString)
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{
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db = new SQLiteConnection(connectionString);
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db.Open();
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}
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// 创建表：根据表名和字段定义创建表
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// 参数: tableName - 表名
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// 参数: columns - 字段定义字典，键为字段名，值为字段类型
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// 例如: CreateTable("Users", new Dictionary<string, string> { {"Id", "INTEGER"}, {"Name", "TEXT"} });
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public void CreateTable(string tableName, Dictionary<string, string> columns)
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{
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// 构建列定义的字符串
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var columnsDefinition = string.Join(", ", columns.Select(c => $"{c.Key} {c.Value}"));
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string createTableQuery = $"CREATE TABLE IF NOT EXISTS {tableName} ({columnsDefinition});";
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using (var cmd = new SQLiteCommand(createTableQuery, db))
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{
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cmd.ExecuteNonQuery();
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}
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}
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// 向已存在的表中添加新列
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// 参数: tableName - 表名
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// 参数: columnName - 要添加的列名
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// 参数: columnType - 列的数据类型
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// 例如: AddColumn("Users", "Email", "TEXT");
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public void AddColumn(string tableName, string columnName, string columnType)
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{
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// 检查表是否存在
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if (!TableExists(tableName))
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{
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throw new ArgumentException($"表 '{tableName}' 不存在");
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}
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// 检查列是否已存在
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if (ColumnExists(tableName, columnName))
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{
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Console.WriteLine($"列 '{columnName}' 在表 '{tableName}' 中已存在");
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return;
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}
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// 构建添加列的SQL语句
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string addColumnQuery = $"ALTER TABLE {tableName} ADD COLUMN {columnName} {columnType};";
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using (var cmd = new SQLiteCommand(addColumnQuery, db))
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{
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cmd.ExecuteNonQuery();
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}
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Console.WriteLine($"已向表 '{tableName}' 添加列 '{columnName}'");
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}
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// 检查表是否存在
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private bool TableExists(string tableName)
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{
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string query = "SELECT count(*) FROM sqlite_master WHERE type='table' AND name=@tableName;";
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using (var cmd = new SQLiteCommand(query, db))
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{
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cmd.Parameters.AddWithValue("@tableName", tableName);
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var result = cmd.ExecuteScalar();
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return Convert.ToInt32(result) > 0;
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}
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}
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// 检查列是否已存在
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private bool ColumnExists(string tableName, string columnName)
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{
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string query = $"PRAGMA table_info({tableName});";
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using (var cmd = new SQLiteCommand(query, db))
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using (var reader = cmd.ExecuteReader())
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{
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while (reader.Read())
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{
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if (reader["name"].ToString().Equals(columnName, StringComparison.OrdinalIgnoreCase))
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{
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return true;
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}
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}
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}
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return false;
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}
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// 批量添加多个列
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// 参数: tableName - 表名
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// 参数: columns - 字段定义字典，键为字段名，值为字段类型
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// 例如: AddColumns("Users", new Dictionary<string, string> { {"Email", "TEXT"}, {"Age", "INTEGER"} });
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public void AddColumns(string tableName, Dictionary<string, string> columns)
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{
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foreach (var column in columns)
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{
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AddColumn(tableName, column.Key, column.Value);
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}
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}
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// 插入数据：向指定表插入一条记录
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// 参数: tableName - 表名
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// 参数: columnValues - 字段和对应值的字典
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// 例如: InsertData("Users", new Dictionary<string, object> { {"Name", "John"}, {"Age", 30} });
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public void InsertData(string tableName, Dictionary<string, object> columnValues)
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{
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// 构建列和参数的字符串
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var columns = string.Join(", ", columnValues.Keys);
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var parameters = string.Join(", ", columnValues.Keys.Select(k => "@" + k));
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string insertQuery = $"INSERT INTO {tableName} ({columns}) VALUES ({parameters})";
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using (var cmd = new SQLiteCommand(insertQuery, db))
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{
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foreach (var kvp in columnValues)
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{
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cmd.Parameters.AddWithValue("@" + kvp.Key, kvp.Value);
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}
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cmd.ExecuteNonQuery();
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}
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}
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// 查询数据：执行任意查询语句并返回结果
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// 参数: query - SQL查询语句
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// 参数: parameters - 可选的查询参数字典
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// 例如: SelectData("SELECT * FROM Users WHERE Age > @age", new Dictionary<string, object> { {"age", 25} });
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public List<Dictionary<string, object>> SelectData(string query, Dictionary<string, object> parameters = null)
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{
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var result = new List<Dictionary<string, object>>();
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using (var cmd = new SQLiteCommand(query, db))
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{
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// 添加查询参数（如果有的话）
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if (parameters != null)
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{
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foreach (var kvp in parameters)
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{
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cmd.Parameters.AddWithValue("@" + kvp.Key, kvp.Value);
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}
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}
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using (SQLiteDataReader reader = cmd.ExecuteReader())
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{
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while (reader.Read())
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{
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var row = new Dictionary<string, object>();
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for (int i = 0; i < reader.FieldCount; i++)
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{
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row[reader.GetName(i)] = reader.GetValue(i);
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}
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result.Add(row);
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}
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}
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}
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return result;
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}
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// 更新数据：根据条件更新指定表中的记录
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// 参数: tableName - 表名
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// 参数: columnValues - 需要更新的字段和对应值的字典
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// 参数: condition - 更新条件
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// 例如: UpdateData("Users", new Dictionary<string, object> { {"Age", 31} }, "Name = 'John'");
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public void UpdateData(string tableName, Dictionary<string, object> columnValues, string condition)
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{
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// 构建SET子句
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var setClause = string.Join(", ", columnValues.Keys.Select(k => $"{k} = @{k}"));
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string updateQuery = $"UPDATE {tableName} SET {setClause} WHERE {condition}";
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using (var cmd = new SQLiteCommand(updateQuery, db))
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{
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foreach (var kvp in columnValues)
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{
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cmd.Parameters.AddWithValue("@" + kvp.Key, kvp.Value);
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}
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cmd.ExecuteNonQuery();
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}
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}
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// 删除数据：根据条件删除指定表中的记录
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// 参数: tableName - 表名
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// 参数: condition - 删除条件
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// 例如: DeleteData("Users", "Age < 18");
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public void DeleteData(string tableName, string condition)
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{
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string deleteQuery = $"DELETE FROM {tableName} WHERE {condition}";
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using (var cmd = new SQLiteCommand(deleteQuery, db))
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{
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cmd.ExecuteNonQuery();
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}
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}
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// 支持事务操作：允许在同一个事务中执行多个操作
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// 参数: transactionActions - 一个包含多个数据库操作的委托
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// 例如: ExecuteTransaction(() =>
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// {
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// InsertData("Users", new Dictionary<string, object> { {"Name", "Alice"}, {"Age", 28} });
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// UpdateData("Users", new Dictionary<string, object> { {"Age", 29} }, "Name = 'Bob'");
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// });
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public void ExecuteTransaction(Action transactionActions)
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{
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using (var transaction = db.BeginTransaction())
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{
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try
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{
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transactionActions.Invoke(); // 执行多个操作
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transaction.Commit(); // 提交事务
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}
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catch (Exception)
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{
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transaction.Rollback(); // 回滚事务
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throw;
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}
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}
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}
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// 删除所有表
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public void DropAllTables()
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{
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// 获取所有表名
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string getTablesQuery = "SELECT name FROM sqlite_master WHERE type='table';";
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var tables = SelectData(getTablesQuery);
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foreach (var table in tables)
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{
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string tableName = table["name"].ToString();
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string dropTableQuery = $"DROP TABLE IF EXISTS {tableName};";
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using (var cmd = new SQLiteCommand(dropTableQuery, db))
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{
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cmd.ExecuteNonQuery();
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}
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}
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}
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// 释放资源，关闭数据库连接
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// 确保数据库连接在对象销毁时被正确关闭
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public void Dispose()
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{
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if (!disposed)
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{
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if (db != null && db.State == ConnectionState.Open)
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{
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db.Close();
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db.Dispose();
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}
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disposed = true;
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}
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GC.SuppressFinalize(this);
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}
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// 析构函数，调用Dispose释放资源
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~SQLite()
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{
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Dispose();
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}
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}
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}
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