2020寒假学习记录（15）——编程实现利用 DataFrame 读写 MySQL 的数据

（1）在 MySQL 数据库中新建数据库 sparktest，再创建表 employee，包含如表 6-2 所示的 两行数据。

表 6-2 employee 表原有数据

id name gender Age

1 Alice F 22

2 John M 25

hadoop@hadoop-virtual-machine:~$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or g.
Y

mysql> create database sparktest;
Query OK, 1 row affected (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hive               |
| mysql              |
| performance_schema |
| sparktest          |
| sys                |
+--------------------+
6 rows in set (0.10 sec)


mysql> use sparktest;
Database changed

mysql> create table employee(id int(10), name varchar(20), gender varchar(2),age int(4));
Query OK, 0 rows affected (0.07 sec)

mysql> describe employee;
+--------+-------------+------+-----+---------+-------+
| Field  | Type        | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id     | int(10)     | YES  |     | NULL    |       |
| name   | varchar(20) | YES  |     | NULL    |       |
| gender | varchar(2)  | YES  |     | NULL    |       |
| age    | int(4)      | YES  |     | NULL    |       |
+--------+-------------+------+-----+---------+-------+
4 rows in set (0.12 sec)

mysql> insert into employee values ("1","Alice","F","22")
    -> ;
Query OK, 1 row affected (0.06 sec)

mysql> insert into employee values ("2","John","M","25");
Query OK, 1 row affected (0.01 sec)

（2）配置 Spark 通过 JDBC 连接数据库 MySQL，编程实现利用 DataFrame 插入如表 6-3 所 示的两行数据到 MySQL 中，最后打印出 age 的最大值和 age 的总和。

表 6-3 employee 表新增数据

id name gender age

3 Mary F 26

4 Tom M 23

scala> val jdbcDF = spark.read.format("jdbc").option("url", "jdbc:mysql://localhost:3306/sparktest").option("driver","com.mysql.jdbc.Driver").option("dbtable", "employee").option("user", "root").option("password", "7").load()
jdbcDF: org.apache.spark.sql.DataFrame = [id: int, name: string ... 2 more fields]

scala> jdbcDF.show()
+---+-----+------+---+
| id| name|gender|age|
+---+-----+------+---+
| 1|Alice| F| 22|
| 2| John| M| 25|
+---+-----+------+---+

import java.util.Properties
import org.apache.spark.sql.types._
import org.apache.spark.sql.Row
object TestMySQL {    
    def main(args: Array[String]) {
        val employeeRDD = spark.sparkContext.parallelize(Array("3 Mary F 26","4 Tom M 23")).map(_.split(" "))
        val schema = StructType(List(StructField("id", IntegerType, true),StructField("name", StringType, true),StructField("gender", StringType, true),StructField("age", IntegerType, true)))
        val rowRDD = employeeRDD.map(p => Row(p(0).toInt,p(1).trim, p(2).trim,p(3).toInt))
        val employeeDF = spark.createDataFrame(rowRDD, schema)
        val prop = new Properties()
        prop.put("user", "root") 
        prop.put("password", "hadoop") 
        prop.put("driver","com.mysql.jdbc.Driver")
        employeeDF.write.mode("append").jdbc("jdbc:mysql://localhost:3306/sparktest", sparktest.employee", prop)
        val jdbcDF = spark.read.format("jdbc").option("url", "jdbc:mysql://localhost:3306/sparktest").option("driver","com.mysql.jdbc.Driver").optio n("dbtable","employee").option("user","root").option("password", "hadoop").load() jdbcDF.agg("age" -> "max", "age" -> "sum")    
    }
}