C# SQLite 高级功能详解(推荐)_Asp.net

sqlite 基础介绍

sqlite 是一个轻量级的嵌入式关系数据库，特别适合桌面应用程序和移动应用程序。它支持 acid 特性，提供了强大的事务控制功能。

主要特点

无需服务器配置
跨平台支持
支持标准 sql 语法
文件级数据库
支持事务和 acid 特性

环境配置

首先安装必要的 nuget 包：

<packagereference include="microsoft.data.sqlite" version="7.0.0" />
<packagereference include="system.data.sqlite" version="1.0.118" />

基础连接设置：

using microsoft.data.sqlite;
using system.data;
using system.data.sqlite;
public class databaseconnection
{
    private readonly string _connectionstring;
    public databaseconnection(string databasepath)
    {
        _connectionstring = $"data source={databasepath};";
    }
    public sqliteconnection getconnection()
    {
        return new sqliteconnection(_connectionstring);
    }
}

事务处理详解

事务基础概念

事务是数据库操作的基本单元，必须满足 acid 特性：

原子性(atomicity)：事务中的所有操作要么全部完成，要么全部不执行
一致性(consistency)：事务前后数据库状态保持一致
隔离性(isolation)：并发事务之间相互隔离
持久性(durability)：事务提交后，数据永久保存

基本事务操作

public class transactionexample
{
    private readonly string _connectionstring;
    public transactionexample(string connectionstring)
    {
        _connectionstring = connectionstring;
    }
    // 基本事务操作
    public void basictransactionexample()
    {
        using var connection = new sqliteconnection(_connectionstring);
        connection.open();
        using var transaction = connection.begintransaction();
        try
        {
            // 创建命令并关联事务
            using var command = connection.createcommand();
            command.transaction = transaction;
            // 执行多个相关操作
            command.commandtext = "insert into users (name, email) values (@name, @email)";
            command.parameters.addwithvalue("@name", "张三");
            command.parameters.addwithvalue("@email", "zhangsan@example.com");
            command.executenonquery();
            command.parameters.clear();
            command.commandtext = "insert into userprofiles (userid, age) values (last_insert_rowid(), @age)";
            command.parameters.addwithvalue("@age", 25);
            command.executenonquery();
            // 提交事务
            transaction.commit();
            console.writeline("事务成功提交");
        }
        catch (exception ex)
        {
            // 回滚事务
            transaction.rollback();
            console.writeline($"事务回滚: {ex.message}");
            throw;
        }
    }
}

高级事务控制

public class advancedtransactioncontrol
{
    private readonly string _connectionstring;
    public advancedtransactioncontrol(string connectionstring)
    {
        _connectionstring = connectionstring;
    }
    // 设置事务隔离级别
    public void transactionwithisolationlevel()
    {
        using var connection = new sqliteconnection(_connectionstring);
        connection.open();
        // sqlite 支持的隔离级别
        using var transaction = connection.begintransaction(isolationlevel.serializable);
        try
        {
            var command = connection.createcommand();
            command.transaction = transaction;
            // 执行业务逻辑
            command.commandtext = "update accounts set balance = balance - 100 where id = 1";
            int affected = command.executenonquery();
            if (affected == 0)
            {
                throw new invalidoperationexception("账户不存在或余额不足");
            }
            command.commandtext = "update accounts set balance = balance + 100 where id = 2";
            command.executenonquery();
            transaction.commit();
        }
        catch
        {
            transaction.rollback();
            throw;
        }
    }
    // 嵌套事务（保存点）
    public void savepointexample()
    {
        using var connection = new sqliteconnection(_connectionstring);
        connection.open();
        using var maintransaction = connection.begintransaction();
        try
        {
            var command = connection.createcommand();
            command.transaction = maintransaction;
            // 主要操作
            command.commandtext = "insert into orders (customerid, amount) values (1, 100)";
            command.executenonquery();
            // 创建保存点
            command.commandtext = "savepoint sp1";
            command.executenonquery();
            try
            {
                // 可能失败的操作
                command.commandtext = "insert into orderdetails (orderid, productid) values (last_insert_rowid(), 999)";
                command.executenonquery();
            }
            catch
            {
                // 回滚到保存点
                command.commandtext = "rollback to sp1";
                command.executenonquery();
                // 执行替代操作
                command.commandtext = "insert into orderdetails (orderid, productid) values (last_insert_rowid(), 1)";
                command.executenonquery();
            }
            // 释放保存点
            command.commandtext = "release sp1";
            command.executenonquery();
            maintransaction.commit();
        }
        catch
        {
            maintransaction.rollback();
            throw;
        }
    }
}

事务性业务逻辑封装

public class bankingservice
{
    private readonly string _connectionstring;
    public bankingservice(string connectionstring)
    {
        _connectionstring = connectionstring;
    }
    // 转账操作 - 事务应用实例
    public async task<bool> transfermoney(int fromaccountid, int toaccountid, decimal amount)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var transaction = await connection.begintransactionasync();
        try
        {
            // 检查源账户余额
            decimal sourcebalance = await getaccountbalance(connection, transaction, fromaccountid);
            if (sourcebalance < amount)
            {
                throw new invalidoperationexception("余额不足");
            }
            // 从源账户扣款
            await updateaccountbalance(connection, transaction, fromaccountid, -amount);
            // 向目标账户加款
            await updateaccountbalance(connection, transaction, toaccountid, amount);
            // 记录转账历史
            await recordtransferhistory(connection, transaction, fromaccountid, toaccountid, amount);
            await transaction.commitasync();
            return true;
        }
        catch (exception ex)
        {
            await transaction.rollbackasync();
            console.writeline($"转账失败: {ex.message}");
            return false;
        }
    }
    private async task<decimal> getaccountbalance(sqliteconnection connection, sqlitetransaction transaction, int accountid)
    {
        using var command = connection.createcommand();
        command.transaction = transaction;
        command.commandtext = "select balance from accounts where id = @id for update"; // 行锁定
        command.parameters.addwithvalue("@id", accountid);
        var result = await command.executescalarasync();
        return result != null ? convert.todecimal(result) : 0;
    }
    private async task updateaccountbalance(sqliteconnection connection, sqlitetransaction transaction, int accountid, decimal amount)
    {
        using var command = connection.createcommand();
        command.transaction = transaction;
        command.commandtext = "update accounts set balance = balance + @amount where id = @id";
        command.parameters.addwithvalue("@amount", amount);
        command.parameters.addwithvalue("@id", accountid);
        int affected = await command.executenonqueryasync();
        if (affected == 0)
        {
            throw new invalidoperationexception($"账户 {accountid} 不存在");
        }
    }
    private async task recordtransferhistory(sqliteconnection connection, sqlitetransaction transaction, 
        int fromaccountid, int toaccountid, decimal amount)
    {
        using var command = connection.createcommand();
        command.transaction = transaction;
        command.commandtext = @"
            insert into transferhistory (fromaccountid, toaccountid, amount, transferdate) 
            values (@from, @to, @amount, @date)";
        command.parameters.addwithvalue("@from", fromaccountid);
        command.parameters.addwithvalue("@to", toaccountid);
        command.parameters.addwithvalue("@amount", amount);
        command.parameters.addwithvalue("@date", datetime.utcnow);
        await command.executenonqueryasync();
    }
}

连接管理与连接池

sqlite 连接管理和池化：

public class connectionpoolmanager
{
    private readonly concurrentqueue<sqliteconnection> _connectionpool;
    private readonly string _connectionstring;
    private readonly int _maxpoolsize;
    private int _currentpoolsize;
    public connectionpoolmanager(string connectionstring, int maxpoolsize = 10)
    {
        _connectionstring = connectionstring;
        _maxpoolsize = maxpoolsize;
        _connectionpool = new concurrentqueue<sqliteconnection>();
        _currentpoolsize = 0;
    }
    public async task<sqliteconnection> getconnectionasync()
    {
        if (_connectionpool.trydequeue(out var connection))
        {
            if (connection.state == connectionstate.open)
            {
                return connection;
            }
            else
            {
                connection.dispose();
                interlocked.decrement(ref _currentpoolsize);
            }
        }
        // 创建新连接
        connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        interlocked.increment(ref _currentpoolsize);
        return connection;
    }
    public void returnconnection(sqliteconnection connection)
    {
        if (connection.state == connectionstate.open && _currentpoolsize <= _maxpoolsize)
        {
            _connectionpool.enqueue(connection);
        }
        else
        {
            connection.dispose();
            interlocked.decrement(ref _currentpoolsize);
        }
    }
    public void dispose()
    {
        while (_connectionpool.trydequeue(out var connection))
        {
            connection.dispose();
        }
    }
}

批量操作优化

public class batchoperations
{
    private readonly string _connectionstring;
    public batchoperations(string connectionstring)
    {
        _connectionstring = connectionstring;
    }
    // 批量插入优化
    public async task bulkinsertoptimized(list<user> users)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var transaction = await connection.begintransactionasync();
        try
        {
            // 方法1：使用参数化批量插入
            using var command = connection.createcommand();
            command.transaction = transaction;
            command.commandtext = "insert into users (name, email, age) values (@name, @email, @age)";
            var nameparam = command.parameters.add("@name", sqlitetype.text);
            var emailparam = command.parameters.add("@email", sqlitetype.text);
            var ageparam = command.parameters.add("@age", sqlitetype.integer);
            foreach (var user in users)
            {
                nameparam.value = user.name;
                emailparam.value = user.email;
                ageparam.value = user.age;
                await command.executenonqueryasync();
            }
            await transaction.commitasync();
        }
        catch
        {
            await transaction.rollbackasync();
            throw;
        }
    }
    // 超大批量插入（分批处理）
    public async task bulkinsertlargedataset(ienumerable<user> users, int batchsize = 1000)
    {
        var userlist = users.tolist();
        int totalbatches = (int)math.ceiling((double)userlist.count / batchsize);
        for (int batch = 0; batch < totalbatches; batch++)
        {
            var batchusers = userlist.skip(batch * batchsize).take(batchsize);
            await bulkinsertoptimized(batchusers.tolist());
            // 可选：报告进度
            console.writeline($"处理批次 {batch + 1}/{totalbatches}");
        }
    }
    // 使用 values 子句批量插入
    public async task bulkinsertwithvalues(list<user> users)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var transaction = await connection.begintransactionasync();
        try
        {
            const int batchsize = 500;
            for (int i = 0; i < users.count; i += batchsize)
            {
                var batch = users.skip(i).take(batchsize);
                var values = new list<string>();
                var parameters = new list<sqliteparameter>();
                int paramindex = 0;
                foreach (var user in batch)
                {
                    values.add($"(@name{paramindex}, @email{paramindex}, @age{paramindex})");
                    parameters.add(new sqliteparameter($"@name{paramindex}", user.name));
                    parameters.add(new sqliteparameter($"@email{paramindex}", user.email));
                    parameters.add(new sqliteparameter($"@age{paramindex}", user.age));
                    paramindex++;
                }
                using var command = connection.createcommand();
                command.transaction = transaction;
                command.commandtext = $"insert into users (name, email, age) values {string.join(", ", values)}";
                command.parameters.addrange(parameters.toarray());
                await command.executenonqueryasync();
            }
            await transaction.commitasync();
        }
        catch
        {
            await transaction.rollbackasync();
            throw;
        }
    }
}

异步操作

public class asyncdatabaseoperations
{
    private readonly string _connectionstring;
    public asyncdatabaseoperations(string connectionstring)
    {
        _connectionstring = connectionstring;
    }
    // 异步事务操作
    public async task<bool> processorderasync(order order, list<orderitem> items)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var transaction = await connection.begintransactionasync();
        try
        {
            // 插入订单
            long orderid = await insertorderasync(connection, transaction, order);
            // 并行处理订单项
            var tasks = items.select(item => insertorderitemasync(connection, transaction, orderid, item));
            await task.whenall(tasks);
            // 更新库存
            await updateinventoryasync(connection, transaction, items);
            await transaction.commitasync();
            return true;
        }
        catch (exception ex)
        {
            await transaction.rollbackasync();
            console.writeline($"订单处理失败: {ex.message}");
            return false;
        }
    }
    private async task<long> insertorderasync(sqliteconnection connection, sqlitetransaction transaction, order order)
    {
        using var command = connection.createcommand();
        command.transaction = transaction;
        command.commandtext = @"
            insert into orders (customerid, orderdate, totalamount) 
            values (@customerid, @orderdate, @totalamount);
            select last_insert_rowid();";
        command.parameters.addwithvalue("@customerid", order.customerid);
        command.parameters.addwithvalue("@orderdate", order.orderdate);
        command.parameters.addwithvalue("@totalamount", order.totalamount);
        var result = await command.executescalarasync();
        return convert.toint64(result);
    }
    private async task insertorderitemasync(sqliteconnection connection, sqlitetransaction transaction, 
        long orderid, orderitem item)
    {
        using var command = connection.createcommand();
        command.transaction = transaction;
        command.commandtext = @"
            insert into orderitems (orderid, productid, quantity, unitprice) 
            values (@orderid, @productid, @quantity, @unitprice)";
        command.parameters.addwithvalue("@orderid", orderid);
        command.parameters.addwithvalue("@productid", item.productid);
        command.parameters.addwithvalue("@quantity", item.quantity);
        command.parameters.addwithvalue("@unitprice", item.unitprice);
        await command.executenonqueryasync();
    }
    private async task updateinventoryasync(sqliteconnection connection, sqlitetransaction transaction, 
        list<orderitem> items)
    {
        using var command = connection.createcommand();
        command.transaction = transaction;
        foreach (var item in items)
        {
            command.commandtext = "update products set stock = stock - @quantity where id = @productid";
            command.parameters.clear();
            command.parameters.addwithvalue("@quantity", item.quantity);
            command.parameters.addwithvalue("@productid", item.productid);
            int affected = await command.executenonqueryasync();
            if (affected == 0)
            {
                throw new invalidoperationexception($"产品 {item.productid} 库存更新失败");
            }
        }
    }
}

索引优化

public class indexoptimization
{
    private readonly string _connectionstring;
    public indexoptimization(string connectionstring)
    {
        _connectionstring = connectionstring;
    }
    // 创建和管理索引
    public async task createoptimalindexes()
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var command = connection.createcommand();
        // 单列索引
        command.commandtext = "create index if not exists idx_users_email on users(email)";
        await command.executenonqueryasync();
        // 复合索引
        command.commandtext = "create index if not exists idx_orders_customer_date on orders(customerid, orderdate)";
        await command.executenonqueryasync();
        // 部分索引（条件索引）
        command.commandtext = "create index if not exists idx_orders_pending on orders(orderdate) where status = 'pending'";
        await command.executenonqueryasync();
        // 唯一索引
        command.commandtext = "create unique index if not exists idx_users_username on users(username)";
        await command.executenonqueryasync();
    }
    // 分析查询性能
    public async task analyzequeryperformance(string query)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var command = connection.createcommand();
        command.commandtext = $"explain query plan {query}";
        using var reader = await command.executereaderasync();
        console.writeline("查询执行计划:");
        while (await reader.readasync())
        {
            console.writeline($"id: {reader[0]}, parent: {reader[1]}, notused: {reader[2]}, detail: {reader[3]}");
        }
    }
    // 索引使用统计
    public async task getindexstatistics()
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var command = connection.createcommand();
        command.commandtext = @"
            select name, sql 
            from sqlite_master 
            where type = 'index' 
            and sql is not null
            order by name";
        using var reader = await command.executereaderasync();
        console.writeline("数据库索引列表:");
        while (await reader.readasync())
        {
            console.writeline($"索引: {reader["name"]}, sql: {reader["sql"]}");
        }
    }
}

锁机制与并发控制

public class concurrencycontrol
{
    private readonly string _connectionstring;
    private readonly semaphoreslim _semaphore;
    public concurrencycontrol(string connectionstring, int maxconcurrentconnections = 5)
    {
        _connectionstring = connectionstring;
        _semaphore = new semaphoreslim(maxconcurrentconnections, maxconcurrentconnections);
    }
    // 悲观锁实现
    public async task<bool> updatewithpessimisticlock(int userid, string newemail)
    {
        await _semaphore.waitasync();
        try
        {
            using var connection = new sqliteconnection(_connectionstring);
            await connection.openasync();
            using var transaction = await connection.begintransactionasync(isolationlevel.serializable);
            try
            {
                // 查询并锁定行
                using var selectcommand = connection.createcommand();
                selectcommand.transaction = transaction;
                selectcommand.commandtext = "select email, version from users where id = @id";
                selectcommand.parameters.addwithvalue("@id", userid);
                using var reader = await selectcommand.executereaderasync();
                if (!await reader.readasync())
                {
                    return false;
                }
                string currentemail = reader["email"].tostring();
                int currentversion = convert.toint32(reader["version"]);
                reader.close();
                // 模拟业务处理时间
                await task.delay(100);
                // 更新数据
                using var updatecommand = connection.createcommand();
                updatecommand.transaction = transaction;
                updatecommand.commandtext = @"
                    update users 
                    set email = @email, version = version + 1, updatedat = @updatedat
                    where id = @id and version = @version";
                updatecommand.parameters.addwithvalue("@email", newemail);
                updatecommand.parameters.addwithvalue("@updatedat", datetime.utcnow);
                updatecommand.parameters.addwithvalue("@id", userid);
                updatecommand.parameters.addwithvalue("@version", currentversion);
                int affected = await updatecommand.executenonqueryasync();
                if (affected > 0)
                {
                    await transaction.commitasync();
                    return true;
                }
                else
                {
                    await transaction.rollbackasync();
                    return false;
                }
            }
            catch
            {
                await transaction.rollbackasync();
                throw;
            }
        }
        finally
        {
            _semaphore.release();
        }
    }
    // 乐观锁实现
    public async task<bool> updatewithoptimisticlock(int userid, string newemail, int expectedversion)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var command = connection.createcommand();
        command.commandtext = @"
            update users 
            set email = @email, version = version + 1, updatedat = @updatedat
            where id = @id and version = @expectedversion";
        command.parameters.addwithvalue("@email", newemail);
        command.parameters.addwithvalue("@updatedat", datetime.utcnow);
        command.parameters.addwithvalue("@id", userid);
        command.parameters.addwithvalue("@expectedversion", expectedversion);
        int affected = await command.executenonqueryasync();
        return affected > 0;
    }
    // 分布式锁模拟
    public async task<bool> tryacquiredistributedlock(string lockname, timespan expiration)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var command = connection.createcommand();
        command.commandtext = @"
            insert or ignore into distributedlocks (lockname, expiresat, createdat)
            values (@lockname, @expiresat, @createdat)";
        command.parameters.addwithvalue("@lockname", lockname);
        command.parameters.addwithvalue("@expiresat", datetime.utcnow.add(expiration));
        command.parameters.addwithvalue("@createdat", datetime.utcnow);
        int affected = await command.executenonqueryasync();
        return affected > 0;
    }
    public async task releaselock(string lockname)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var command = connection.createcommand();
        command.commandtext = "delete from distributedlocks where lockname = @lockname";
        command.parameters.addwithvalue("@lockname", lockname);
        await command.executenonqueryasync();
    }
}

备份与恢复

public class backupandrestore
{
    private readonly string _connectionstring;
    public backupandrestore(string connectionstring)
    {
        _connectionstring = connectionstring;
    }
    // 在线备份
    public async task backupdatabase(string backuppath)
    {
        using var sourceconnection = new sqliteconnection(_connectionstring);
        using var backupconnection = new sqliteconnection($"data source={backuppath}");
        await sourceconnection.openasync();
        await backupconnection.openasync();
        // 使用 sqlite 内置备份 api
        sourceconnection.backupdatabase(backupconnection, "main", "main");
        console.writeline($"数据库备份完成: {backuppath}");
    }
    // 增量备份（通过时间戳）
    public async task incrementalbackup(string backuppath, datetime lastbackuptime)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        // 导出自上次备份以来的更改
        var tables = new[] { "users", "orders", "orderitems" };
        var backupdata = new dictionary<string, list<dictionary<string, object>>>();
        foreach (var table in tables)
        {
            using var command = connection.createcommand();
            command.commandtext = $"select * from {table} where updatedat > @lastbackup";
            command.parameters.addwithvalue("@lastbackup", lastbackuptime);
            using var reader = await command.executereaderasync();
            var tabledata = new list<dictionary<string, object>>();
            while (await reader.readasync())
            {
                var row = new dictionary<string, object>();
                for (int i = 0; i < reader.fieldcount; i++)
                {
                    row[reader.getname(i)] = reader.getvalue(i);
                }
                tabledata.add(row);
            }
            backupdata[table] = tabledata;
        }
        // 序列化备份数据
        var json = system.text.json.jsonserializer.serialize(backupdata, new jsonserializeroptions { writeindented = true });
        await file.writealltextasync(backuppath, json);
        console.writeline($"增量备份完成: {backuppath}");
    }
    // 事务日志备份
    public async task backupwithtransactionlog(string backuppath)
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var transaction = await connection.begintransactionasync();
        try
        {
            // 创建备份点
            using var command = connection.createcommand();
            command.transaction = transaction;
            command.commandtext = "insert into backuplog (backuptime, backuppath, status) values (@time, @path, 'started')";
            command.parameters.addwithvalue("@time", datetime.utcnow);
            command.parameters.addwithvalue("@path", backuppath);
            await command.executenonqueryasync();
            // 执行实际备份
            await backupdatabase(backuppath);
            // 更新备份状态
            command.commandtext = "update backuplog set status = 'completed' where backuppath = @path";
            await command.executenonqueryasync();
            await transaction.commitasync();
        }
        catch
        {
            await transaction.rollbackasync();
            throw;
        }
    }
    // 验证备份完整性
    public async task<bool> validatebackup(string backuppath)
    {
        try
        {
            using var connection = new sqliteconnection($"data source={backuppath}");
            await connection.openasync();
            using var command = connection.createcommand();
            command.commandtext = "pragma integrity_check";
            var result = await command.executescalarasync();
            return result?.tostring() == "ok";
        }
        catch
        {
            return false;
        }
    }
}

性能优化技巧

public class performanceoptimization
{
    private readonly string _connectionstring;
    public performanceoptimization(string connectionstring)
    {
        _connectionstring = connectionstring;
    }
    // 数据库配置优化
    public async task optimizedatabasesettings()
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var command = connection.createcommand();
        // 设置 wal 模式（写前日志）
        command.commandtext = "pragma journal_mode = wal";
        await command.executenonqueryasync();
        // 设置同步模式
        command.commandtext = "pragma synchronous = normal";
        await command.executenonqueryasync();
        // 设置缓存大小（页数）
        command.commandtext = "pragma cache_size = 10000";
        await command.executenonqueryasync();
        // 设置页面大小
        command.commandtext = "pragma page_size = 4096";
        await command.executenonqueryasync();
        // 启用外键约束
        command.commandtext = "pragma foreign_keys = on";
        await command.executenonqueryasync();
        // 设置临时存储
        command.commandtext = "pragma temp_store = memory";
        await command.executenonqueryasync();
        console.writeline("数据库性能设置已优化");
    }
    // 查询优化示例
    public async task optimizedqueries()
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        // 使用参数化查询和适当的索引
        using var command = connection.createcommand();
        // 优化：使用覆盖索引
        command.commandtext = @"
            select userid, count(*) as ordercount, sum(totalamount) as totalspent
            from orders 
            where orderdate between @startdate and @enddate
            group by userid
            having count(*) > 5
            order by totalspent desc
            limit 100";
        command.parameters.addwithvalue("@startdate", datetime.now.addmonths(-3));
        command.parameters.addwithvalue("@enddate", datetime.now);
        using var reader = await command.executereaderasync();
        var results = new list<customersummary>();
        while (await reader.readasync())
        {
            results.add(new customersummary
            {
                userid = reader.getint32("userid"),
                ordercount = reader.getint32("ordercount"),
                totalspent = reader.getdecimal("totalspent")
            });
        }
    }
    // 批量数据处理优化
    public async task optimizedbatchprocessing<t>(ienumerable<t> items, func<t, sqlitecommand, task> processitem)
    {
        const int batchsize = 1000;
        const int maxconcurrency = environment.processorcount;
        var semaphore = new semaphoreslim(maxconcurrency);
        var batches = items.chunk(batchsize);
        var tasks = batches.select(async batch =>
        {
            await semaphore.waitasync();
            try
            {
                using var connection = new sqliteconnection(_connectionstring);
                await connection.openasync();
                using var transaction = await connection.begintransactionasync();
                try
                {
                    using var command = connection.createcommand();
                    command.transaction = transaction;
                    foreach (var item in batch)
                    {
                        await processitem(item, command);
                    }
                    await transaction.commitasync();
                }
                catch
                {
                    await transaction.rollbackasync();
                    throw;
                }
            }
            finally
            {
                semaphore.release();
            }
        });
        await task.whenall(tasks);
    }
    // 性能监控
    public async task monitorperformance()
    {
        using var connection = new sqliteconnection(_connectionstring);
        await connection.openasync();
        using var command = connection.createcommand();
        // 获取数据库统计信息
        var stats = new dictionary<string, object>();
        command.commandtext = "pragma page_count";
        stats["pagecount"] = await command.executescalarasync();
        command.commandtext = "pragma page_size";
        stats["pagesize"] = await command.executescalarasync();
        command.commandtext = "pragma cache_size";
        stats["cachesize"] = await command.executescalarasync();
        command.commandtext = "pragma journal_mode";
        stats["journalmode"] = await command.executescalarasync();
        console.writeline("数据库性能统计:");
        foreach (var stat in stats)
        {
            console.writeline($"{stat.key}: {stat.value}");
        }
    }
}

实体类定义

// 支持类定义
public class user
{
    public int id { get; set; }
    public string name { get; set; }
    public string email { get; set; }
    public string username { get; set; }
    public int age { get; set; }
    public int version { get; set; }
    public datetime updatedat { get; set; }
}
public class order
{
    public int id { get; set; }
    public int customerid { get; set; }
    public datetime orderdate { get; set; }
    public decimal totalamount { get; set; }
    public string status { get; set; }
}
public class orderitem
{
    public int id { get; set; }
    public int orderid { get; set; }
    public int productid { get; set; }
    public int quantity { get; set; }
    public decimal unitprice { get; set; }
}
public class customersummary
{
    public int userid { get; set; }
    public int ordercount { get; set; }
    public decimal totalspent { get; set; }
}

数据库表结构

-- 创建示例表结构
create table users (
    id integer primary key autoincrement,
    name text not null,
    email text unique not null,
    username text unique,
    age integer,
    version integer default 0,
    updatedat datetime default current_timestamp
);
create table orders (
    id integer primary key autoincrement,
    customerid integer not null,
    orderdate datetime not null,
    totalamount decimal(10,2) not null,
    status text default 'pending',
    updatedat datetime default current_timestamp,
    foreign key (customerid) references users(id)
);
create table orderitems (
    id integer primary key autoincrement,
    orderid integer not null,
    productid integer not null,
    quantity integer not null,
    unitprice decimal(10,2) not null,
    foreign key (orderid) references orders(id)
);
create table accounts (
    id integer primary key autoincrement,
    accountnumber text unique not null,
    balance decimal(15,2) not null default 0
);
create table transferhistory (
    id integer primary key autoincrement,
    fromaccountid integer not null,
    toaccountid integer not null,
    amount decimal(15,2) not null,
    transferdate datetime not null,
    foreign key (fromaccountid) references accounts(id),
    foreign key (toaccountid) references accounts(id)
);
create table distributedlocks (
    lockname text primary key,
    expiresat datetime not null,
    createdat datetime not null
);
create table backuplog (
    id integer primary key autoincrement,
    backuptime datetime not null,
    backuppath text not null,
    status text not null
);

总结

本文档详细介绍了 c# 与 sqlite 数据库的高级功能使用，重点包括：

事务处理：从基本事务到嵌套事务，涵盖了各种事务控制场景
连接管理：连接池化和资源优化
批量操作：高效的数据批量处理方法
异步编程：现代异步操作模式
性能优化：索引、查询优化和系统配置
并发控制：悲观锁、乐观锁和分布式锁
备份恢复：数据安全和灾难恢复

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2025年06月17日 • Asp.net •我要评论