[SPARK-25769][SQL]change nested columns from to .

Author: huaxingao

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

@@ -98,8 +98,18 @@ case class UnresolvedTableValuedFunction(
  */
 case class UnresolvedAttribute(nameParts: Seq[String]) extends Attribute with Unevaluable {
 
-  def name: String =
-    nameParts.map(n => if (n.contains(".")) s"`$n`" else n).mkString(".")
+  def name: String = {
+    nameParts.map(n =>
+      if (n.contains(".")) s"`$n`"
+      else {
+        if (nameParts.length > 1) {
+          s"`$n`"
+        } else {
+          n
+        }
+      }
+    ).mkString(".")
+  }
 
   override def exprId: ExprId = throw new UnresolvedException(this, "exprId")
   override def dataType: DataType = throw new UnresolvedException(this, "dataType")

sql/core/src/test/resources/sql-tests/results/columnresolution-negative.sql.out

@@ -81,7 +81,7 @@ SELECT t1.i1 FROM t1, mydb1.t1
 struct<>
 -- !query 9 output
 org.apache.spark.sql.AnalysisException
-Reference 't1.i1' is ambiguous, could be: mydb1.t1.i1, mydb1.t1.i1.; line 1 pos 7
+Reference '`t1`.`i1`' is ambiguous, could be: mydb1.t1.i1, mydb1.t1.i1.; line 1 pos 7
 
 
 -- !query 10
@@ -90,7 +90,7 @@ SELECT mydb1.t1.i1 FROM t1, mydb1.t1
 struct<>
 -- !query 10 output
 org.apache.spark.sql.AnalysisException
-Reference 'mydb1.t1.i1' is ambiguous, could be: mydb1.t1.i1, mydb1.t1.i1.; line 1 pos 7
+Reference '`mydb1`.`t1`.`i1`' is ambiguous, could be: mydb1.t1.i1, mydb1.t1.i1.; line 1 pos 7
 
 
 -- !query 11
@@ -108,7 +108,7 @@ SELECT t1.i1 FROM t1, mydb2.t1
 struct<>
 -- !query 12 output
 org.apache.spark.sql.AnalysisException
-Reference 't1.i1' is ambiguous, could be: mydb1.t1.i1, mydb2.t1.i1.; line 1 pos 7
+Reference '`t1`.`i1`' is ambiguous, could be: mydb1.t1.i1, mydb2.t1.i1.; line 1 pos 7
 
 
 -- !query 13
@@ -134,7 +134,7 @@ SELECT t1.i1 FROM t1, mydb1.t1
 struct<>
 -- !query 15 output
 org.apache.spark.sql.AnalysisException
-Reference 't1.i1' is ambiguous, could be: mydb2.t1.i1, mydb1.t1.i1.; line 1 pos 7
+Reference '`t1`.`i1`' is ambiguous, could be: mydb2.t1.i1, mydb1.t1.i1.; line 1 pos 7
 
 
 -- !query 16
@@ -152,7 +152,7 @@ SELECT t1.i1 FROM t1, mydb2.t1
 struct<>
 -- !query 17 output
 org.apache.spark.sql.AnalysisException
-Reference 't1.i1' is ambiguous, could be: mydb2.t1.i1, mydb2.t1.i1.; line 1 pos 7
+Reference '`t1`.`i1`' is ambiguous, could be: mydb2.t1.i1, mydb2.t1.i1.; line 1 pos 7
 
 
 -- !query 18
@@ -161,7 +161,7 @@ SELECT db1.t1.i1 FROM t1, mydb2.t1
 struct<>
 -- !query 18 output
 org.apache.spark.sql.AnalysisException
-cannot resolve '`db1.t1.i1`' given input columns: [mydb2.t1.i1, mydb2.t1.i1]; line 1 pos 7
+cannot resolve '`db1`.`t1`.`i1`' given input columns: [mydb2.t1.i1, mydb2.t1.i1]; line 1 pos 7
 
 
 -- !query 19
@@ -186,7 +186,7 @@ SELECT mydb1.t1 FROM t1
 struct<>
 -- !query 21 output
 org.apache.spark.sql.AnalysisException
-cannot resolve '`mydb1.t1`' given input columns: [mydb1.t1.i1]; line 1 pos 7
+cannot resolve '`mydb1`.`t1`' given input columns: [mydb1.t1.i1]; line 1 pos 7
 
 
 -- !query 22
@@ -221,7 +221,7 @@ SELECT mydb1.t1.i1 FROM t1
 struct<>
 -- !query 25 output
 org.apache.spark.sql.AnalysisException
-cannot resolve '`mydb1.t1.i1`' given input columns: [mydb2.t1.i1]; line 1 pos 7
+cannot resolve '`mydb1`.`t1`.`i1`' given input columns: [mydb2.t1.i1]; line 1 pos 7
 
 
 -- !query 26

sql/core/src/test/resources/sql-tests/results/describe-table-column.sql.out

@@ -188,7 +188,7 @@ DESC FORMATTED desc_complex_col_table col.x
 struct<>
 -- !query 14 output
 org.apache.spark.sql.AnalysisException
-DESC TABLE COLUMN command does not support nested data types: col.x;
+DESC TABLE COLUMN command does not support nested data types: `col`.`x`;
 
 
 -- !query 15

sql/core/src/test/resources/sql-tests/results/query_regex_column.sql.out

@@ -45,7 +45,7 @@ SELECT t.`(a)?+.+` FROM testData2 t WHERE a = 1
 struct<>
 -- !query 4 output
 org.apache.spark.sql.AnalysisException
-cannot resolve 't.`(a)?+.+`' given input columns: [t.A, t.B, t.c, t.d]; line 1 pos 7
+cannot resolve '`t`.`(a)?+.+`' given input columns: [t.A, t.B, t.c, t.d]; line 1 pos 7
 
 
 -- !query 5

sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala

@@ -1143,7 +1143,7 @@ class SQLQuerySuite extends QueryTest with SharedSQLContext {
             |order by struct.a, struct.b
             |""".stripMargin)
     }
-    assert(error.message contains "cannot resolve '`struct.a`' given input columns: [a, b]")
+    assert(error.message contains "cannot resolve '`struct`.`a`' given input columns: [a, b]")
 
   }
 
@@ -2702,7 +2702,7 @@ class SQLQuerySuite extends QueryTest with SharedSQLContext {
 
       val e = intercept[AnalysisException](sql("SELECT v.i from (SELECT i FROM v)"))
       assert(e.message ==
-        "cannot resolve '`v.i`' given input columns: [__auto_generated_subquery_name.i]")
+        "cannot resolve '`v`.`i`' given input columns: [__auto_generated_subquery_name.i]")
 
       checkAnswer(sql("SELECT __auto_generated_subquery_name.i from (SELECT i FROM v)"), Row(1))
     }