Support alias for UnPivot statement (see discussion #1374) (#1380)

- Changed JSqlParserCC.jjt file to add the alias to the UnPivot lexical entity.
- Added Alias to the UnPivot object.
- Improved SelectDeParser to correctly deparse SubSelect's UnPivot component.

Author: fabriziodelfranco

src/main/java/net/sf/jsqlparser/statement/select/UnPivot.java

@@ -9,6 +9,7 @@
  */
 package net.sf.jsqlparser.statement.select;
 
+import net.sf.jsqlparser.expression.Alias;
 import net.sf.jsqlparser.schema.Column;
 
 import java.util.List;
@@ -20,6 +21,7 @@ public class UnPivot {
     private Column unpivotClause;
     private List<Column> unpivotForClause;
     private List<SelectExpressionItem> unpivotInClause;
+    private Alias alias;
 
     public void accept(PivotVisitor pivotVisitor) {
         pivotVisitor.visit(this);
@@ -69,11 +71,20 @@ public String toString() {
                 + (includeNullsSpecified && !includeNulls ? " EXCLUDE NULLS" : "")
                 + " (" + unpivotClause
                 + " FOR " + PlainSelect.getStringList(unpivotForClause, true, unpivotForClause != null && unpivotForClause.size() > 1)
-                + " IN " + PlainSelect.getStringList(unpivotInClause, true, true) + ")";
+                + " IN " + PlainSelect.getStringList(unpivotInClause, true, true) + ")"
+                + (alias!=null ? alias.toString() : "");
     }
 
     public UnPivot withIncludeNulls(boolean includeNulls) {
         this.setIncludeNulls(includeNulls);
         return this;
     }
+
+    public Alias getAlias() {
+        return alias;
+    }
+
+    public void setAlias(Alias alias) {
+        this.alias = alias;
+    }
 }

src/main/java/net/sf/jsqlparser/util/deparser/SelectDeParser.java

@@ -253,12 +253,17 @@ public void visit(SubSelect subSelect) {
         buffer.append(subSelect.isUseBrackets() ? ")" : "");
         Alias alias = subSelect.getAlias();
         if (alias != null) {
-            buffer.append(alias.toString());
+            buffer.append(alias);
         }
         Pivot pivot = subSelect.getPivot();
         if (pivot != null) {
             pivot.accept(this);
         }
+
+        UnPivot unPivot = subSelect.getUnPivot();
+        if (unPivot != null) {
+            unPivot.accept(this);
+        }
     }
 
     @Override
@@ -308,6 +313,9 @@ public void visit(UnPivot unpivot) {
                 .append(PlainSelect.getStringList(unpivotForClause, true,
                         unpivotForClause != null && unpivotForClause.size() > 1))
                 .append(" IN ").append(PlainSelect.getStringList(unpivot.getUnPivotInClause(), true, true)).append(")");
+        if (unpivot.getAlias() != null) {
+            buffer.append(unpivot.getAlias().toString());
+        }
     }
 
     @Override

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -2273,6 +2273,7 @@ UnPivot UnPivot():
     Column unpivotClause;
     List<Column> unpivotForClause;
     List<SelectExpressionItem> unpivotInClause;
+    Alias alias = null;
 }
 {
     <K_UNPIVOT>
@@ -2284,10 +2285,12 @@ UnPivot UnPivot():
     unpivotInClause = PivotSingleInItems()
     ")"
     ")"
+    [ alias = Alias() ]
     {
         retval.setUnPivotClause(unpivotClause);
         retval.setUnPivotForClause(unpivotForClause);
         retval.setUnPivotInClause(unpivotInClause);
+        retval.setAlias(alias);
         return retval;
     }
 }

src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java

@@ -2516,6 +2516,31 @@ public void testPivotFunction() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed("SELECT to_char((SELECT col1 FROM (SELECT times_purchased, state_code FROM customers t) PIVOT (count(state_code) FOR state_code IN ('NY', 'CT', 'NJ', 'FL', 'MO')) ORDER BY times_purchased)) FROM DUAL");
     }
 
+    @Test
+    public void testUnPivotWithAlias() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT simulation_id, un_piv_alias.signal, un_piv_alias.val AS value FROM" +
+                " (SELECT simulation_id," +
+                    " convert(numeric(18, 2), sum(convert(int, init_on))) DosingOnStatus_TenMinutes_sim," +
+                    " convert(numeric(18, 2), sum(CASE WHEN pump_status = 0 THEN 10 ELSE 0 END)) AS DosingOffDurationHour_Hour_sim" +
+                " FROM ft_simulation_result" +
+                " WHERE simulation_id = 210 AND data_timestamp BETWEEN convert(datetime, '2021-09-14', 120) AND convert(datetime, '2021-09-18', 120)" +
+                " GROUP BY simulation_id) sim_data" +
+                " UNPIVOT" +
+                " (" +
+                "val" +
+                " FOR signal IN (DosingOnStatus_TenMinutes_sim, DosingOnDuration_Hour_sim)" +
+                ") un_piv_alias");
+    }
+
+   @Test
+    public void testUnPivot() throws JSQLParserException {
+        String stmt = "SELECT * FROM sale_stats" +
+                " UNPIVOT (" +
+                "quantity" +
+                " FOR product_code IN (product_a AS 'A', product_b AS 'B', product_c AS 'C'))";
+       assertSqlCanBeParsedAndDeparsed(stmt);
+    }
+
     @Test
     public void testPivotWithAlias() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed("SELECT * FROM (SELECT * FROM mytable LEFT JOIN mytable2 ON Factor_ID = Id) f PIVOT (max(f.value) FOR f.factoryCode IN (ZD, COD, SW, PH))");