[SPARK-16734][EXAMPLES][SQL] Revise examples of all language bindings

## What changes were proposed in this pull request?

This PR makes various minor updates to examples of all language bindings to make sure they are consistent with each other. Some typos and missing parts (JDBC example in Scala/Java/Python) are also fixed.

## How was this patch tested?

Manually tested.

Author: Cheng Lian <lian@databricks.com>

Closes #14368 from liancheng/revise-examples.

2 files changed, 18 insertions, 6 deletions

diff --git a/examples/src/main/scala/org/apache/spark/examples/sql/SQLDataSourceExample.scala b/examples/src/main/scala/org/apache/spark/examples/sql/SQLDataSourceExample.scala
index 0caba12af0..dc3915a488 100644
--- a/examples/src/main/scala/org/apache/spark/examples/sql/SQLDataSourceExample.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/sql/SQLDataSourceExample.scala
@@ -25,7 +25,7 @@ object SQLDataSourceExample {
   def main(args: Array[String]) {
     val spark = SparkSession
       .builder()
-      .appName("Spark SQL Data Soures Example")
+      .appName("Spark SQL data sources example")
       .config("spark.some.config.option", "some-value")
       .getOrCreate()
 
@@ -33,6 +33,7 @@ object SQLDataSourceExample {
     runBasicParquetExample(spark)
     runParquetSchemaMergingExample(spark)
     runJsonDatasetExample(spark)
+    runJdbcDatasetExample(spark)
 
     spark.stop()
   }
@@ -99,10 +100,10 @@ object SQLDataSourceExample {
     // The final schema consists of all 3 columns in the Parquet files together
     // with the partitioning column appeared in the partition directory paths
     // root
-    // |-- value: int (nullable = true)
-    // |-- square: int (nullable = true)
-    // |-- cube: int (nullable = true)
-    // |-- key : int (nullable = true)
+    //  |-- value: int (nullable = true)
+    //  |-- square: int (nullable = true)
+    //  |-- cube: int (nullable = true)
+    //  |-- key: int (nullable = true)
     // $example off:schema_merging$
   }
 
@@ -145,4 +146,15 @@ object SQLDataSourceExample {
     // $example off:json_dataset$
   }
 
+  private def runJdbcDatasetExample(spark: SparkSession): Unit = {
+    // $example on:jdbc_dataset$
+    val jdbcDF = spark.read
+      .format("jdbc")
+      .option("url", "jdbc:postgresql:dbserver")
+      .option("dbtable", "schema.tablename")
+      .option("user", "username")
+      .option("password", "password")
+      .load()
+    // $example off:jdbc_dataset$
+  }
 }
diff --git a/examples/src/main/scala/org/apache/spark/examples/sql/SparkSQLExample.scala b/examples/src/main/scala/org/apache/spark/examples/sql/SparkSQLExample.scala
index 952c074d03..5cd437d017 100644
--- a/examples/src/main/scala/org/apache/spark/examples/sql/SparkSQLExample.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/sql/SparkSQLExample.scala
@@ -42,7 +42,7 @@ object SparkSQLExample {
     // $example on:init_session$
     val spark = SparkSession
       .builder()
-      .appName("Spark SQL Example")
+      .appName("Spark SQL basic example")
       .config("spark.some.config.option", "some-value")
       .getOrCreate()