code refactor.

Author: jiangxb1987

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala

@@ -617,18 +617,18 @@ class Analyzer(
     private def lookupTableFromCatalog(
         u: UnresolvedRelation,
         defaultDatabase: Option[String] = None): LogicalPlan = {
-      val db = u.tableIdentifier.database.orElse(defaultDatabase)
-      val tableIdentWithDb = u.tableIdentifier.copy(database = db)
+      val tableIdentWithDb = u.tableIdentifier.copy(database = u.tableIdentifier.database
+        .orElse(defaultDatabase))
       try {
         catalog.lookupRelation(tableIdentWithDb, u.alias)
       } catch {
         case _: NoSuchTableException =>
           u.failAnalysis(s"Table or view not found: ${tableIdentWithDb.unquotedString}")
         // If the database is defined and that database is not found, throw an AnalysisException.
         // Note that if the database is not defined, it is possible we are looking up a temp view.
-        case _: NoSuchDatabaseException if db.isDefined =>
+        case e: NoSuchDatabaseException =>
           u.failAnalysis(s"Table or view not found: ${tableIdentWithDb.unquotedString}, the " +
-            s"database ${db.get} doesn't exsits.")
+            s"database ${e.db} doesn't exsits.")
       }
     }
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/NoSuchItemException.scala

@@ -25,7 +25,7 @@ import org.apache.spark.sql.catalyst.catalog.CatalogTypes.TablePartitionSpec
  * Thrown by a catalog when an item cannot be found. The analyzer will rethrow the exception
  * as an [[org.apache.spark.sql.AnalysisException]] with the correct position information.
  */
-class NoSuchDatabaseException(db: String) extends AnalysisException(s"Database '$db' not found")
+class NoSuchDatabaseException(val db: String) extends AnalysisException(s"Database '$db' not found")
 
 class NoSuchTableException(db: String, table: String)
   extends AnalysisException(s"Table or view '$table' not found in database '$db'")

sql/core/src/test/scala/org/apache/spark/sql/execution/SQLViewSuite.scala

@@ -22,8 +22,7 @@ import org.apache.spark.sql.catalyst.TableIdentifier
 import org.apache.spark.sql.catalyst.analysis.NoSuchTableException
 import org.apache.spark.sql.test.{SharedSQLContext, SQLTestUtils}
 
-class SimpleSQLViewSuite extends SQLViewSuite with SharedSQLContext {
-}
+class SimpleSQLViewSuite extends SQLViewSuite with SharedSQLContext
 
 /**
  * A suite for testing view related functionality.