How to specify multiple tables in Spark SQL?

Question

I have a code where I need to set three tables. To do that I need to call jdbc function three times for each table. See code below

val props = new Properties
    props.setProperty("user", "root")
    props.setProperty("password", "pass")

val df0 = sqlContext.read.jdbc(
  "jdbc:mysql://127.0.0.1:3306/Firm42", "company", props)

val df1 = sqlContext.read.jdbc(
  "jdbc:mysql://127.0.0.1:3306/Firm42", "employee", props)

val df2 = sqlContext.read.jdbc(
  "jdbc:mysql://127.0.0.1:3306/Firm42", "company_employee", props)

df0.registerTempTable("company")
df1.registerTempTable("employee")
df2.registerTempTable("company_employee")

val rdf = sqlContext.sql(
  """some_sql_query_with_joins_of_various_tables""".stripMargin)

rdf.show

Is it possible to simplify my code? Or maybe there is some way to specify multiple tables somewhere in SQL configuration.

Answer 1

DRY:

val url = "jdbc:mysql://127.0.0.1:3306/Firm42"
val tables =  List("company", "employee", "company_employee")

val dfs = for {
    table <- tables
} yield (table, sqlContext.read.jdbc(url, table, props))

for {
  (name, df) <- dfs
} df.registerTempTable(name) 

Don't need data frames? Skip first loop:

for {
  table <- tables
} sqlContext.read.jdbc(url, table, props).registerTempTable(table)