Fix error example

Author: wangyum

docs/sql-data-sources-jdbc.md

@@ -64,9 +64,9 @@ the following case-insensitive options:
             Example:<br>
             <code>
                spark.read.format("jdbc")<br>
-               &nbsp&nbsp .option("dbtable", "(select c1, c2 from t1) as subq")<br>
-               &nbsp&nbsp .option("partitionColumn", "subq.c1"<br>
-               &nbsp&nbsp .load()
+                 .option("url", jdbcUrl)<br>
+                 .option("query", "select c1, c2 from t1")<br>
+                 .load()
             </code></li>
       </ol>
     </td>

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCOptions.scala

@@ -137,9 +137,13 @@ class JDBCOptions(
        |the partition columns using the supplied subquery alias to resolve any ambiguity.
        |Example :
        |spark.read.format("jdbc")
-       |        .option("dbtable", "(select c1, c2 from t1) as subq")
-       |        .option("partitionColumn", "subq.c1"
-       |        .load()
+       |  .option("url", jdbcUrl)
+       |  .option("dbtable", "(select c1, c2 from t1) as subq")
+       |  .option("partitionColumn", "c1")
+       |  .option("lowerBound", "1")
+       |  .option("upperBound", "100")
+       |  .option("numPartitions", "3")
+       |  .load()
      """.stripMargin
   )
 

sql/core/src/test/scala/org/apache/spark/sql/jdbc/JDBCSuite.scala

@@ -1348,9 +1348,13 @@ class JDBCSuite extends QueryTest
          |the partition columns using the supplied subquery alias to resolve any ambiguity.
          |Example :
          |spark.read.format("jdbc")
-         |        .option("dbtable", "(select c1, c2 from t1) as subq")
-         |        .option("partitionColumn", "subq.c1"
-         |        .load()
+         |  .option("url", jdbcUrl)
+         |  .option("dbtable", "(select c1, c2 from t1) as subq")
+         |  .option("partitionColumn", "c1")
+         |  .option("lowerBound", "1")
+         |  .option("upperBound", "100")
+         |  .option("numPartitions", "3")
+         |  .load()
      """.stripMargin
     val e5 = intercept[RuntimeException] {
       sql(