How to get table names from SQL query?

Question

I want to get all the tables names from a sql query in Spark using Scala.

Lets say user sends a SQL query which looks like:

select * from table_1 as a left join table_2 as b on a.id=b.id

I would like to get all tables list like table_1 and table_2.

Is regex the only option ?

Answer 1

Thanks a lot @Swapnil Chougule for the answer. That inspired me to offer an idiomatic way of collecting all the tables in a structured query.

scala> spark.version
res0: String = 2.3.1

def getTables(query: String): Seq[String] = {
  val logicalPlan = spark.sessionState.sqlParser.parsePlan(query)
  import org.apache.spark.sql.catalyst.analysis.UnresolvedRelation
  logicalPlan.collect { case r: UnresolvedRelation => r.tableName }
}

val query = "select * from table_1 as a left join table_2 as b on a.id=b.id"
scala> getTables(query).foreach(println)
table_1
table_2