当写入数据到外部数据库时，Flink 会使用 DDL 中定义的主键。如果定义了主键，则连接器将以 upsert 模式工作，否则连接器将以 append 模式工作

package cn.edu.tju.demo2;import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.table.api.DataTypes;
import org.apache.flink.table.api.Table;
import org.apache.flink.table.api.TableResult;
import org.apache.flink.table.api.bridge.java.StreamTableEnvironment;
import org.apache.flink.table.descriptors.*;
import org.apache.flink.types.Row;public class Test41 {//demo 是MySQL中已经创建好的表//create table demo (userId varchar(50) not null,total bigint,avgVal double);private static String FILE_PATH = "info.txt";public static void main(String[] args) throws Exception {StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();env.setParallelism(1);StreamTableEnvironment tableEnv = StreamTableEnvironment.create(env);tableEnv.connect(new FileSystem().path(FILE_PATH)).withFormat(new Csv()).withSchema(new Schema().field("userId", DataTypes.VARCHAR(50)).field("ts", DataTypes.INT()).field("val", DataTypes.DOUBLE())).createTemporaryTable("input");Table dataTable = tableEnv.from("input");Table aggregateTable = dataTable.groupBy("userId").select("userId, userId.count as total, val.avg as avgVal");String sql="create table jdbcOutputTable (" +" userId varchar(50) not null,total bigint,avgVal double " +") with (" +" 'connector.type' = 'jdbc', " +" 'connector.url' = 'jdbc:mysql://xx.xx.xx.xx:3306/test', " +" 'connector.table' = 'demo', " +" 'connector.driver' = 'com.mysql.jdbc.Driver', " +" 'connector.username' = 'root', " +" 'connector.password' = 123456' )";tableEnv.sqlUpdate(sql);aggregateTable.insertInto("jdbcOutputTable");tableEnv.execute("my job");}
}

文件info.txt

user1,1680000890,31.6
user2,1681111900,38.3
user1,1680000890,34.9