Spark: convert string to Date - dataframe

Question

I'm using spark/scala
I have a dataframe. There are columns year/month/day with value, for ex. 2020/9/2. How can I add a column to the same dataframe with conversion to datetime (yyyy-mm-dd)?
I found how to convert date from String to Date format, but I can't find a solution how to combine values and convert it to datetime.
thanks for any advice or hint

Answer 1

You can use the to_date function.
val df1 = Seq(
("2020/9/2"),
("2020/9/15"),
("2020/9/30")
).toDF("str")
val df2 = df1.withColumn("dt", to_date(col("str"), "y/M/d"))
df2.show()

Answer 2

I do some test, I think you can use my examples to convert date. I hope I can help you.
package com.jackpan.spark.examples
import org.apache.spark.sql.SparkSession
import org.apache.spark.sql.types._
import org.apache.spark.sql.functions._
object SomeExamples {
def main(args: Array[String]): Unit = {
val spark = SparkSession
.builder()
.appName("SomeExamples")
.getOrCreate()
val dataDF = spark.createDataFrame(Seq(("2022", "12", "09"), ("2022", "12", "19"),
("2022", "12", "15"))).toDF("year", "month", "day")
dataDF.withColumn("dateStr",
concat(col("year"), lit("-"),col("month"), lit("-"), col("day")))
.withColumn("date", to_date(col("dateStr"), "yyyy-MM-dd"))
.show(false)
}
}
And this function show result is diplay like below :
+----+-----+---+----------+----------+
|year|month|day|dateStr |date |
+----+-----+---+----------+----------+
|2022|12 |09 |2022-12-09|2022-12-09|
|2022|12 |19 |2022-12-19|2022-12-19|
|2022|12 |15 |2022-12-15|2022-12-15|
+----+-----+---+----------+----------+