实现效果：

设计思路：
1. 开启数据库及表的cdc，定时查询cdc表数据，封装sql语句(通过执行类型，主键;修改类型的cdc数据只取最后更新的记录)，添加到离线数据表；
2. 线程定时查询离线数据表，更新远程库数据；
3. 远程库数据被更改又会产生cdc数据，对此数据进行拦截；

配置文件说明：

{
"AsyncInterval": 30000,
"Drivers": [
{
"RefreshTime": 5000,
"Enable": 1,
"SrcConnect": "Data Source=192.168.8.77;Initial Catalog=master;User ID=sa;Pwd=Nflg1234",
"SrcMap": [ "dbsync2|student,table1,table2,table3", "dbsync3|*" ],
"SrcUpdateCDC": 1,
"DstConnect": [ "Data Source=192.168.8.81;Initial Catalog=master;User ID=sa;Pwd=Nflg1234" ]
}
]
}

或

{
"AsyncInterval": 25000,
"Drivers": [
{
"RefreshTime": 10000,
"Enable": 1,
"SrcConnect": "Data Source=192.168.8.77;Initial Catalog=master;User ID=sa;Pwd=Nflg1234",
"SrcMap": [ "testsync1|*"],
"SrcUpdateCDC": 1,
"DstConnect": [ "Data Source=192.168.8.81;Initial Catalog=master;User ID=sa;Pwd=Nflg1234" ]
},
{
"RefreshTime": 10000,
"Enable": 1,
"SrcConnect": "Data Source=192.168.8.81;Initial Catalog=master;User ID=sa;Pwd=Nflg1234",
"SrcMap": [ "testsync1|*" ],
"SrcUpdateCDC": 1,
"DstConnect": [ "Data Source=192.168.8.77;Initial Catalog=master;User ID=sa;Pwd=Nflg1234" ]
}
]
}

1. 设置同步间隔时间
2. 根据不同的配置文件，加载不同的模式，多驱动（Drivers 1主1备-单向同步，1主1主-双向同步，2主1备-多库汇总）,多机同步(DstConnect),多库同多表同步(SrcMap,dbsync2|*表示监听该数据库下的所有表),设置刷新时间(RefreshTime)，是否启用(Enable)，是否重置cdc数据（SrcUpdateCDC）

数据表说明：

async_data 离线数据表
id 主键自增 INTEGER
connect_str 连接字符串 NVARCHAR(255)
excute_sql 需要同步的sql语句 NVARCHAR(255)
cdc_time cdc时间 DATETIME
event_time event时间 DATETIME
db_name 数据库名 NVARCHAR(255)
table_name 表名 NVARCHAR(255)
table_pk 表主键 NVARCHAR(255)
excute_type 执行类型（I/U/D） NVARCHAR(255)

sqlserver cdc表（日志表）中如果一条id多次更新，取最新一条数据
sqlite asy_data表(离线数据表)，入库时，查dbname + table + pk，无记录则添加，有记录比较cdc记录时间，如果时间更新则更新sql语句

特殊数据处理：
uniqueidentifier类型的数据转为NULL，数据中含有'的替换''

核心代码：

using SqlServerAsync.Util.config;
using SqlServerAsync.Util.sqlite;
using SqlServerAsync.Util.sqlite.model;
using System;
using System.Collections.Generic;
using System.Data;
using System.Threading;namespace SqlServerAsync.Util
{public class SqlServerCDC{public void Listen(Driver driver){var update_cdc = driver.SrcUpdateCDC == 1 ? true : false;var enable = driver.Enable == 1 ? true : false;foreach (var map in driver.SrcMap){StartCDC(driver.SrcConnect, driver.DstConnect, driver.RefreshTime, enable, update_cdc, map);}}void StartCDC(string srcconnect, List<string> dstconnect, int refreshTime, bool enable, bool update_cdc, string map){try{var freeSql = new FreeSql.FreeSqlBuilder().UseConnectionString(FreeSql.DataType.SqlServer, srcconnect).UseNoneCommandParameter(true)// 不使用参数化.UseAutoSyncStructure(false)// 不同步表结构.Build();var arrayMap = map.Split('|');var db = arrayMap[0];var tbs = arrayMap[1];string[] arrayTB = null;var dstStr = string.Join("#", dstconnect);if (!enable){Program.AddLog($"禁用监听,来源={srcconnect},目标数={dstconnect.Count},目标={dstStr},db={db},Tables={tbs}");return;}string sql = string.Empty;Dictionary<string, Table> dicTable = new Dictionary<string, Table>();Program.AddLog($"启用监听,来源={srcconnect},目标数={dstconnect.Count},目标={dstStr},db={db},Tables={tbs}");if ("*" == tbs){// 查询db下所有表名sql = $"use {db};select TABLE_NAME from {db}.information_schema.tables where TABLE_SCHEMA='dbo' and TABLE_NAME not in('systranschemas','sysdiagrams')";DataTable dtAll = freeSql.Ado.ExecuteDataTable(sql); var rowCount = dtAll.Rows.Count; if (rowCount > 0) arrayTB = new string[rowCount]; for (int i = 0; i < rowCount; i++){arrayTB[i] = dtAll.Rows[i]["TABLE_NAME"].ToString();}}else{arrayTB = tbs.Split(',');}if (null == arrayTB || 0 == arrayTB.Length){Program.AddLog($"数据库{db},查无数据表 ×");return;}// 开启SQL Server数据库CDCsql = $"use {db};if exists(select 1 from {db}.sys.databases where name='{db}' and is_cdc_enabled=0)\n" +"begin\n" +$"exec {db}.sys.sp_cdc_enable_db\n" +"end";freeSql.Ado.ExecuteNonQuery(sql);// 查询库cdc是否开启成功sql = $"use {db};select is_cdc_enabled from {db}.sys.databases where name='{db}'";DataTable dtCDC_DB = freeSql.Ado.ExecuteDataTable(sql);if (dtCDC_DB.Rows.Count <= 0 || !Convert.ToBoolean(dtCDC_DB.Rows[0]["is_cdc_enabled"])){Program.AddLog($"数据库CDC开启失败({db}) ×");return;}Program.AddLog($"数据库CDC开启成功({db}) √");foreach (var table in arrayTB){if (string.IsNullOrEmpty(table)) continue;if (update_cdc){// 关闭单张表的CDC功能sql = $"use {db};if exists(select 1 from {db}.sys.tables where name='{table}' AND is_tracked_by_cdc=1)\n" +"begin\n" +$"exec {db}.sys.sp_cdc_disable_table @source_schema='dbo',@source_name='{table}',@capture_instance='dbo_{table}'" +"end";freeSql.Ado.ExecuteNonQuery(sql);}// 开启单张表的CDC功能sql = $"use {db};if exists(select 1 from {db}.sys.tables where name='{table}' AND is_tracked_by_cdc=0)\n" +"begin\n" +$"exec {db}.sys.sp_cdc_enable_table\n" +"@source_schema='dbo',\n" +$"@source_name='{table}',\n" +"@capture_instance=NULL,\n" +"@supports_net_changes=1,\n" +"@role_name=NULL\n" +"end";freeSql.Ado.ExecuteNonQuery(sql);// 查询表cdc是否开启成功sql = $"use {db};select is_tracked_by_cdc from {db}.sys.tables WHERE name='{table}'";DataTable dtCDC_TB = freeSql.Ado.ExecuteDataTable(sql);if (dtCDC_TB.Rows.Count <= 0 || !Convert.ToBoolean(dtCDC_TB.Rows[0]["is_tracked_by_cdc"])){Program.AddLog($"数据表CDC开启失败({table}) ×");continue;}Program.AddLog($"数据表CDC开启成功({table}) √");Table tb = new Table() { Name = table };// 获取字段名，是否主键，字段类型sql = $"use {db};SELECT distinct col.name AS 'Name', idx.is_primary_key as 'IsPK',TYPE_NAME(system_type_id) as 'Type'\n" +$"FROM sys.columns col\n" +$"LEFT JOIN sys.index_columns idxcol ON col.object_id=idxcol.object_id AND col.column_id=idxcol.column_id\n" +$"LEFT JOIN sys.indexes idx ON idxcol.object_id=idx.object_id AND idxcol.index_id=idx.index_id\n" +$"WHERE col.object_id=OBJECT_ID('{table}')";List<Field> lstField = freeSql.Ado.Query<Field>(sql);foreach (var field in lstField){var ispk = Convert.ToBoolean(field.IsPK);if (ispk){tb.LstPKField.Add(field);// 主键，用于更新删除}else{tb.LstDataField.Add(field);}}dicTable.Add(table, tb);}Program.AddLog($"监听成功,{db}");// 定时轮询ThreadPool.QueueUserWorkItem(delegate{Dictionary<string, string> dicTBUpdatePK = new Dictionary<string, string>();while (true){try{ foreach (var item in dicTable){dicTBUpdatePK.Clear();var table_name = item.Key;var tableEntity = item.Value;// cdc表查询//__$start_lsn ：与相应更改的提交事务关联的日志序列号(LSN)//__$end_lsn ： （在 SQL Server 2008中，此列始终为 NULL）//__$seqval ：对事务内的行更改顺序//__$operation ：源表DML操作var cdc_table_name = $"{db}.cdc.dbo_{table_name}_CT";sql = $"use {db};select sys.fn_cdc_map_lsn_to_time(__$start_lsn) as cdctime,* from {cdc_table_name}";// 查询cdc时间var dt = freeSql.Ado.ExecuteDataTable(sql);table_name = $"{db}.dbo." + table_name;for (int i = 0; i < dt.Rows.Count; i++){var row = dt.Rows[i];var lstPKField = tableEntity.LstPKField;var lstDataField = tableEntity.LstDataField;var cdctime = Convert.ToDateTime(row["cdctime"]);var operation = Convert.ToInt32(row["__$operation"]);var seqval = (byte[])(row["__$seqval"]);// __$start_lsn代表事件时间，并发时，会有相同的情况，改用__$seqvalvar str_seqval = BitConverter.ToString(seqval, 0).Replace("-", string.Empty);if (3 == operation){continue;}var sql_cdc_execute = string.Empty;string table_pk = string.Empty;foreach (var field1 in lstPKField){table_pk += field1.Name + "='" + row[field1.Name] + "' and ";}table_pk = table_pk.Substring(0, table_pk.Length - 5);string cdc_dic_pk = table_name + ";" + table_pk;// cdc表中过滤多条表中一条记录多次更新，取最新一条数据(查询过的数据利用字典存储)string str_seqval1 = string.Empty;if (4 == operation){if (dicTBUpdatePK.ContainsKey(cdc_dic_pk)){str_seqval1 = dicTBUpdatePK[cdc_dic_pk];}else{// 查询多次更新后的最新值sql = $"use {db};select top 1 __$seqval from {cdc_table_name} where {table_pk} and __$operation=4 order by __$seqval desc";var dtlsn = freeSql.Ado.ExecuteDataTable(sql);var seqval1 = (byte[])(dtlsn.Rows[0]["__$seqval"]);str_seqval1 = BitConverter.ToString(seqval1, 0).Replace("-", string.Empty);dicTBUpdatePK.Add(cdc_dic_pk, str_seqval1);}}// 删除cdc表数据sql = $"use {db};delete from {cdc_table_name} where __$seqval=CONVERT(BINARY(10), '{str_seqval}', 2)";freeSql.Ado.ExecuteNonQuery(sql);string excute_type = string.Empty;switch (operation){case 1:// 删除excute_type = BaseEnum.Delete;sql_cdc_execute = $"delete from {table_name} where {table_pk}";break;case 2:// 插入excute_type = BaseEnum.Insert;string insertField = string.Empty;string insertValue = string.Empty;foreach (var field1 in lstPKField){ insertField += field1.Name + ",";insertValue += HandleSpecialData(field1.Type, row[field1.Name]) + ",";}foreach (var field2 in lstDataField){insertField += field2.Name + ",";insertValue += HandleSpecialData(field2.Type, row[field2.Name]) + ",";} insertField = insertField.Substring(0, insertField.Length - 1);insertValue = insertValue.Substring(0, insertValue.Length - 1);sql_cdc_execute = $"insert into {table_name} ({insertField}) values({insertValue})";break;case 3:break;case 4:// 修改 if (str_seqval == str_seqval1)// 最新的数据{excute_type = BaseEnum.Update;string updateData = string.Empty; foreach (var field2 in lstDataField){updateData += field2.Name + "=" + HandleSpecialData(field2.Type, row[field2.Name]) + ",";}updateData = updateData.Substring(0, updateData.Length - 1);sql_cdc_execute = $"update {table_name} set {updateData} where {table_pk}";}break;}if (!string.IsNullOrEmpty(sql_cdc_execute)){foreach (var dst in dstconnect){bool add = true; string key1 = srcconnect + "_" + table_name + "_" + table_pk; // A同步B，B更新后，CDC日志返回A，这边做截取if (Program.DicExecuted.ContainsKey(key1)){add = false;string removedValue;Program.DicExecuted.TryRemove(key1, out removedValue);}else{// 修改以最后时间的数据为准var entity = SqliteHelper.GetUpdateAsyncData(db, table_name, table_pk);if (null == entity){var asyncdata = new AsyncData() { ConnectStr = dst, ExcuteSQL = sql_cdc_execute, CDCTime = cdctime, EventTime = DateTime.Now, DBName = db, TableName = table_name, TablePK = table_pk, ExcuteType = excute_type };SqliteHelper.InsertAsyncData(asyncdata);}else{// 比较时间if (DateTime.Compare(entity.CDCTime, cdctime) < 0){SqliteHelper.UpdateAsyncData(dst, sql_cdc_execute, entity.Id);}else{add = false;}}if (add){if (dst.Contains("192.168.8.81")){Console.WriteLine("111");}Program.AddLog($"添加,dst:{dst},sql：{sql_cdc_execute}");}}}} }}}catch (Exception ex){Program.AddLog($"Listen Error,ex:{ex.Message}");}Thread.Sleep(refreshTime);}});}catch (Exception ex){Program.AddLog($"[Error] 初始化CDC异常,errmsg:{ex.Message}");}}/// <summary>/// 特殊数据类型处理 1. uniqueidentifier为空时，设置为NULL；2. 单引号，转成双号/// </summary>/// <param name="val"></param>/// <returns></returns>public string HandleSpecialData(string type, object val){if (null == val) return string.Empty;string ret = val.ToString(); bool special = false;if ("uniqueidentifier" == type.ToLower())// 特殊数据类型处理{if (string.IsNullOrEmpty(ret)){special = true;ret = "NULL";}}if (!special){if (ret.Contains("'")){ret = ret.Replace("'", "''");// 把单引号转成双引号}ret = $"'{ret}'";}return ret;} }public class Table{public string Name { get; set; }public List<Field> LstPKField { get; set; } = new List<Field>();public List<Field> LstDataField { get; set; } = new List<Field>();}public class Field{public string Name { get; set; }public string IsPK { get; set; } public string Type { get; set; }// GUID，uniqueidentifier为空时，改为NULL}
}