使用场景如下，将kafka源表通过flink sql处理成mongodb汇表存入。按照班级进行group by，输出对应班级所有的学生数据集合。请问用flink sql自带的collect函数能实现吗？如果能的话要怎么写sql? 如果不能的话要怎么写UDAF，有例子参考吗？谢谢！ kafka源表：班级学号姓名年龄 1 20001 张三 15 2 20011 李四 16 1 20002 .....

问答 2021-12-08 来自：开发者社区

flink sql是否有json_to_map函数，或者实现方法是怎么样的？

有没有什么办法可以将json转成map呢？类似于str_to_map函数。版本：flink 1.11 planner: blink sql 需求背景： UDF函数通过http请求获得了json字符串，希望能够直接使用json内字段， UDTF可以满足一部分要求，但不灵活，因为定义UDTF时需要指定输出字段及类型，限制很大。 *来自志愿者整理的flink邮件归档

共有60条

< 2 3 4 5 6 >

跳转至： GO

更新时间 2024-06-12 18:59:14

本页面内关键词为智能算法引擎基于机器学习所生成，如有任何问题，可在页面下方点击"联系我们"与我们沟通。

SQL更多函数相关

SQL您可能感兴趣

产品推荐

{"moduleinfo":{"card_count":[{"count_phone":1,"count":1}],"search_count":[{"count_phone":4,"count":4}]},"card":[{"des":"云数据库SQL Server，具有企业许可授权，权限更为开放，引擎功能更为强大。能完美支持Windows平台的.NET架构，支持复杂SQL查询，性能优秀，并有强大的可视化管理工具，帮助您轻松管理数据。","link1":"https://rdsnew.console.aliyun.com/console/buy#/create/rds?initData=%7B%22data%22:%7B%22rds_region%22:%22cn-hangzhou%22,%22rds_dbtype%22:%22mssql%22,%22rds_dbversion%22:%222016_web%22,%22rds_web_type%22:%221%22,%22rds_class%22:%22mssql.x2.medium.w1%22,%22rds_storage%22:%2220%22,%22duration%22:12%7D%7D","link":"https://www.aliyun.com/product/rds/sqlserver","icon":"https://img.alicdn.com/tfs/TB1kuYmv3mTBuNjy1XbXXaMrVXa-200-200.png","btn2":"2016 标准版","tip":"完美兼容windows操作系统，已通过ISO 20000、SOC、PCI-DSS、等保三级等十项安全合规认证。         最新产品和实时动态重磅发布<a href=\"https://www.aliyun.com/product/new?source_type=out_sousuo_feature_0716\" target=\"_blank\">立即查看</a>","btn1":"2016 Web版","link2":"https://rdsnew.console.aliyun.com/console/buy#/create/rds?initData=%7B%22data%22:%7B%22rds_region%22:%22cn-shanghai%22,%22rds_dbtype%22:%22mssql%22,%22rds_dbversion%22:%222016_std_ha%22,%22rds_web_type%22:%221%22,%22rds_class%22:%22mssql.x4.medium.s2%22,%22rds_storage%22:%2220%22,%22duration%22:12%7D%7D","title":"云数据库RDS SQL Server版"}],"search":[{"txt":"SQL Server Web版","link":"https://promotion.aliyun.com/ntms/act/sqlserverweb.html"},{"txt":"SQL Server 标准版/企业版","link":"https://promotion.aliyun.com/ntms/act/sqlservergaokeyong.html"},{"txt":"快速入门SQL Server","link":"https://help.aliyun.com/document_detail/26141.html"},{"txt":"产品动态","link":"https://www.aliyun.com/product/new?source_type=out_sousuo_feature_0716"}],"countinfo":{"search":{"length_pc":0,"length":0},"card":{"length_pc":0,"length":0}},"simplifiedDisplay":"newEdition","newCard":[{"link":"https://www.aliyun.com/product/rds/sqlserver","title":"云数据库 RDS SQL Server 版","des":"云数据库SQL Server，具有企业许可授权，权限更为开放，引擎功能更为强大。能完美支持Windows平台的.NET架构，支持复杂SQL查询，性能优秀，并有强大的可视化管理工具，帮助您轻松管理数据。","btn1":"产品详情","link1":"https://www.aliyun.com/product/rds/sqlserver","btn2":"管理控制台","link2":"https://rdsnext.console.aliyun.com/#/rdsList/cn-hangzhou/basic/","link3":"https://www.aliyun.com/core/online-consult?from=OVtXEBmlH8","btn3":"在线咨询","infoGroup":[{"infoName":"最新活动","infoContent":{"firstContentName":"新用户年付低至3折起","firstContentLink":"https://www.aliyun.com/activity/database/bestoffers","lastContentName":"2核4GB 299元/年","lastContentLink":"https://rdsbuy.console.aliyun.com/newCreate/rds/mssql?initData={\"data\":{\"rds_dbtype\":\"\tmssql\",\"rds_dbversion\":\"2022_web\",\"rds_web_type\":\"1\",\"rds_class\":\"mssql.share2.medium.w1\",\"rds_storage\":\"100\",\"rds_nodetype\":\"Basic\",\"duration\":12,\"rds_storagetype\":\"cloud_auto\",\"rds_arch\":\"X86\"}}"}},{"infoName":"快速入门","infoContent":{"firstContentName":"帮助文档","firstContentLink":"https://help.aliyun.com/product/26090.html","lastContentName":"入门指南","lastContentLink":"https://help.aliyun.com/document_detail/53729.htm"}},{"infoName":"产品动态","infoContent":{"firstContentName":"存储能力全方位升级","firstContentLink":"https://www.aliyun.com/activity/database/rds-storage-upgrade","lastContentLink":"https://help.aliyun.com/zh/rds/bi-monthly-product-report-for-apsaradb-rds-march-april-2025-2","lastContentName":"RDS 产品双月报"}},{"infoName":"客户案例","infoContent":{"firstContentName":"RDS 助力巴黎奥运会系统稳定运行","firstContentLink":"https://help.aliyun.com/zh/rds/apsaradb-rds-for-sql-server/apsaradb-rds-helps-ensure-the-stability-of-the-system-of-the-paris-olympic-games","lastContentName":"","lastContentLink":""}}],"icon":"","ifIcon":"img","iconImg":"https://img.alicdn.com/tfs/TB1FIpvn3gP7K4jSZFqXXamhVXa-200-200.png","contentLink":"https://www.aliyun.com/product/rds/sqlserver"}]}

{"$env":{"JSON":{}},"$page":{"env":"production"},"$context":{"moduleinfo":{"card_count":[{"count_phone":1,"count":1}],"search_count":[{"count_phone":4,"count":4}]},"card":[{"des":"云数据库SQL Server，具有企业许可授权，权限更为开放，引擎功能更为强大。能完美支持Windows平台的.NET架构，支持复杂SQL查询，性能优秀，并有强大的可视化管理工具，帮助您轻松管理数据。","link1":"https://rdsnew.console.aliyun.com/console/buy#/create/rds?initData=%7B%22data%22:%7B%22rds_region%22:%22cn-hangzhou%22,%22rds_dbtype%22:%22mssql%22,%22rds_dbversion%22:%222016_web%22,%22rds_web_type%22:%221%22,%22rds_class%22:%22mssql.x2.medium.w1%22,%22rds_storage%22:%2220%22,%22duration%22:12%7D%7D","link":"https://www.aliyun.com/product/rds/sqlserver","icon":"https://img.alicdn.com/tfs/TB1kuYmv3mTBuNjy1XbXXaMrVXa-200-200.png","btn2":"2016 标准版","tip":"完美兼容windows操作系统，已通过ISO 20000、SOC、PCI-DSS、等保三级等十项安全合规认证。         最新产品和实时动态重磅发布<a href=\"https://www.aliyun.com/product/new?source_type=out_sousuo_feature_0716\" target=\"_blank\">立即查看</a>","btn1":"2016 Web版","link2":"https://rdsnew.console.aliyun.com/console/buy#/create/rds?initData=%7B%22data%22:%7B%22rds_region%22:%22cn-shanghai%22,%22rds_dbtype%22:%22mssql%22,%22rds_dbversion%22:%222016_std_ha%22,%22rds_web_type%22:%221%22,%22rds_class%22:%22mssql.x4.medium.s2%22,%22rds_storage%22:%2220%22,%22duration%22:12%7D%7D","title":"云数据库RDS SQL Server版"}],"search":[{"txt":"SQL Server Web版","link":"https://promotion.aliyun.com/ntms/act/sqlserverweb.html"},{"txt":"SQL Server 标准版/企业版","link":"https://promotion.aliyun.com/ntms/act/sqlservergaokeyong.html"},{"txt":"快速入门SQL Server","link":"https://help.aliyun.com/document_detail/26141.html"},{"txt":"产品动态","link":"https://www.aliyun.com/product/new?source_type=out_sousuo_feature_0716"}],"countinfo":{"search":{"length_pc":0,"length":0},"card":{"length_pc":0,"length":0}},"simplifiedDisplay":"newEdition","newCard":[{"link":"https://www.aliyun.com/product/rds/sqlserver","title":"云数据库 RDS SQL Server 版","des":"云数据库SQL Server，具有企业许可授权，权限更为开放，引擎功能更为强大。能完美支持Windows平台的.NET架构，支持复杂SQL查询，性能优秀，并有强大的可视化管理工具，帮助您轻松管理数据。","btn1":"产品详情","link1":"https://www.aliyun.com/product/rds/sqlserver","btn2":"管理控制台","link2":"https://rdsnext.console.aliyun.com/#/rdsList/cn-hangzhou/basic/","link3":"https://www.aliyun.com/core/online-consult?from=OVtXEBmlH8","btn3":"在线咨询","infoGroup":[{"infoName":"最新活动","infoContent":{"firstContentName":"新用户年付低至3折起","firstContentLink":"https://www.aliyun.com/activity/database/bestoffers","lastContentName":"2核4GB 299元/年","lastContentLink":"https://rdsbuy.console.aliyun.com/newCreate/rds/mssql?initData={\"data\":{\"rds_dbtype\":\"\tmssql\",\"rds_dbversion\":\"2022_web\",\"rds_web_type\":\"1\",\"rds_class\":\"mssql.share2.medium.w1\",\"rds_storage\":\"100\",\"rds_nodetype\":\"Basic\",\"duration\":12,\"rds_storagetype\":\"cloud_auto\",\"rds_arch\":\"X86\"}}"}},{"infoName":"快速入门","infoContent":{"firstContentName":"帮助文档","firstContentLink":"https://help.aliyun.com/product/26090.html","lastContentName":"入门指南","lastContentLink":"https://help.aliyun.com/document_detail/53729.htm"}},{"infoName":"产品动态","infoContent":{"firstContentName":"存储能力全方位升级","firstContentLink":"https://www.aliyun.com/activity/database/rds-storage-upgrade","lastContentLink":"https://help.aliyun.com/zh/rds/bi-monthly-product-report-for-apsaradb-rds-march-april-2025-2","lastContentName":"RDS 产品双月报"}},{"infoName":"客户案例","infoContent":{"firstContentName":"RDS 助力巴黎奥运会系统稳定运行","firstContentLink":"https://help.aliyun.com/zh/rds/apsaradb-rds-for-sql-server/apsaradb-rds-helps-ensure-the-stability-of-the-system-of-the-paris-olympic-games","lastContentName":"","lastContentLink":""}}],"icon":"","ifIcon":"img","iconImg":"https://img.alicdn.com/tfs/TB1FIpvn3gP7K4jSZFqXXamhVXa-200-200.png","contentLink":"https://www.aliyun.com/product/rds/sqlserver"}]}}

云数据库 RDS SQL Server 版

云数据库SQL Server，具有企业许可授权，权限更为开放，引擎功能更为强大。能完美支持Windows平台的.NET架构，支持复杂SQL查询，性能优秀，并有强大的可视化管理工具，帮助您轻松管理数据。

产品详情

管理控制台

在线咨询

Flink SQL中的value1 IN (value2, value3…)函数的作用是什么？

Flink SQL中的DATE string和TIMESTAMP string函数的作用分别是什么？

Flink SQL中的string1 LIKE string2函数表示什么？

Flink SQL中的value1 < value2函数表示什么？

Flink SQL中的value1>value2函数表示什么？

Flink SQL中的value1<>value2函数表示什么？

Flink SQL中的value1=value2函数表示什么？

Flink SQL常用的内置函数有哪些？

flink sql collect函数使用问题

flink sql是否有json_to_map函数，或者实现方法是怎么样的？

SQL函数相关内容

SQL更多函数相关

SQL您可能感兴趣

产品推荐