Insert DataFrame into SQL table with AUTO_INCREMENT column

Question

I have a MySQL table which includes a column that is AUTO_INCREMENT:

CREATE TABLE features (
  id INT NOT NULL AUTO_INCREMENT,
  name CHAR(30),
  value DOUBLE PRECISION
);

I created a DataFrame and wanted to insert it into this table.

case class Feature(name: String, value: Double)
val rdd: RDD[Feature]
val df = rdd.toDF()
df.write.mode(SaveMode.Append).jdbc("jdbc:mysql://...", "features", new Properties)

I get the error, Column count doesn’t match value count at row 1. If I delete the id column it works. How could I insert this data into the table without changing the schema?

Daniel Darabos · Accepted Answer · 2016-04-05 09:57:12Z

4

You have to include an id field in the DataFrame, but its value will be ignored and replaced with the auto-incremented ID. That is:

case class Feature(id: Int, name: String, value: Double)

Then just set id to 0, or any number when you create a Feature.

edited Apr 5, 2016 at 9:57

answered Jul 9, 2015 at 16:00

Daniel Darabos

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10 Comments

Daniel Darabos Over a year ago

Sorry it's not a straight answer, but I barely understand the question. Hope it helps.

yeyimilk Over a year ago

I have known why the error happened while I still don't how to do. Next I will try my best to explain clearly. In my table, I have 5 columns which include id column. However, in my DataFrame, I have only 4 columns, and my DataFrame will map MySQL Table just the first 4 columns and left the fifth columns doesn't map. With SQL, I know how to insert but with spark, I dont know how to do even I had search for the APIs. I hope you can understand or I can send you e-mail if you can understand Chinese.

Daniel Darabos Over a year ago

Okay. So the question is basically how to use insertIntoJDBC with an auto_increment field. Try inserting 0 for the id. Maybe the database will sort it out.

yeyimilk Over a year ago

I know it's bad to ask another unrelated question under this question, but could you tell how to follow you? I don't know how to follow people in stackoverflow

Daniel Darabos Over a year ago

I don't think you can follow people on Stack Overflow. You can subscribe to a tag though! I recommend subscribing to apache-spark!

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