[fix][core] Fixed the issue of aliases being empty when multiple table updates

Author: wt0530

core/src/main/java/org/apache/calcite/sql/SqlUpdate.java

@@ -152,6 +152,10 @@ public SqlNode getTargetTable() {
     return targetTable;
   }
 
+  public void setTargetTable(SqlNode targetTable) {
+    this.targetTable = targetTable;
+  }
+
   /** Returns the alias for the target table of this UPDATE. */
   @Pure
   public @Nullable SqlIdentifier getAlias() {
@@ -186,6 +190,10 @@ public SqlNodeList getAliases() {
     return aliases;
   }
 
+  public void setAliases(SqlNodeList aliases) {
+    this.aliases = aliases;
+  }
+
   public boolean singleTable() {
     return getSourceTables().size() <= 1;
   }
@@ -228,11 +236,25 @@ public void setSourceSelect(SqlSelect sourceSelect) {
         writer.startList(SqlWriter.FrameTypeEnum.SELECT, "UPDATE", "");
     final int opLeft = getOperator().getLeftPrec();
     final int opRight = getOperator().getRightPrec();
-    targetTable.unparse(writer, opLeft, opRight);
-    SqlIdentifier alias = this.alias;
-    if (alias != null) {
-      writer.keyword("AS");
-      alias.unparse(writer, opLeft, opRight);
+    if (singleTable()) {
+      targetTable.unparse(writer, opLeft, opRight);
+      if (alias != null) {
+        writer.keyword("AS");
+        alias.unparse(writer, opLeft, opRight);
+      }
+    } else {
+      for (SqlNode table : sourceTables) {
+        if (table instanceof SqlIdentifier) {
+          ((SqlIdentifier) table).unparse(writer, opLeft, opRight);
+        } else {
+          table.unparse(writer, opLeft, opRight);
+        }
+        writer.keyword("AS");
+        SqlIdentifier alias = (SqlIdentifier) aliases.get(sourceTables.indexOf(table));
+        alias.unparse(writer, opLeft, opRight);
+        writer.sep(",");
+      }
+      // targetTable.unparse(writer, opLeft, opRight);
     }
     final SqlWriter.Frame setFrame =
         writer.startList(SqlWriter.FrameTypeEnum.UPDATE_SET_LIST, "SET", "");

core/src/main/java/org/apache/calcite/sql/validate/SqlValidatorImpl.java

@@ -1728,6 +1728,32 @@ protected SqlSelect createSourceSelectForUpdate(SqlUpdate call) {
               sourceTable,
               alias.getLastName());
     }
+    if (!call.singleTable() && call.getAliases() != null) {
+      if (sourceTable.getKind() == SqlKind.JOIN) {
+        SqlNodeList aliases = new SqlNodeList(call.getAliases().getParserPosition());
+        SqlJoin join = (SqlJoin) sourceTable;
+        SqlNode left = join.getLeft();
+        SqlNode right = join.getRight();
+        SqlNode newLeft = SqlValidatorUtil.addAlias(
+              left,
+              ((SqlIdentifier) call.getAliases().get(0)).getLastName());
+        SqlNode newRight = SqlValidatorUtil.addAlias(
+              right,
+              ((SqlIdentifier) call.getAliases().get(1)).getLastName());
+        sourceTable = new SqlJoin(
+              join.getParserPosition(),
+              newLeft,
+              join.isNaturalNode(),
+              join.getJoinTypeNode(),
+              newRight,
+              join.getConditionTypeNode(),
+              join.getCondition());
+        aliases.add(newLeft);
+        aliases.add(newRight);
+        call.setTargetTable(sourceTable);
+        call.setAliases(aliases);
+      }
+    }
     return new SqlSelect(SqlParserPos.ZERO, null, selectList, sourceTable,
         call.getCondition(), null, null, null, null, null, null, null);
   }