Implemented:

1. UPDATE .. RETURNING col, col as Alias
2. UPDATE .. RETURNING *

Tested:
3. UPDATE .. ORDER BY .. LIMIT .. RETURNING
4. UPDATE .. RETURNING

Item 4 represents the PostgreSQL UPDATE .. RETURNING Syntax without ORDER BY and LIMIT.
See: https://www.postgresql.org/docs/9.5/static/sql-update.html

Author: meganwoods

src/main/java/net/sf/jsqlparser/statement/update/Update.java

@@ -34,6 +34,7 @@
 import net.sf.jsqlparser.statement.select.Select;
 import net.sf.jsqlparser.statement.select.OrderByElement;
 import net.sf.jsqlparser.statement.select.Limit;
+import net.sf.jsqlparser.statement.select.SelectExpressionItem;
 
 /**
  * The update statement.
@@ -51,6 +52,8 @@ public class Update implements Statement {
 	private boolean useSelect = false;
 	private List<OrderByElement> orderByElements;
 	private Limit limit;
+	private boolean returningAllColumns = false;
+	private List<SelectExpressionItem> returningExpressionList = null;
 
 	@Override
 	public void accept(StatementVisitor statementVisitor) {
@@ -157,6 +160,22 @@ public Limit getLimit() {
 		return limit;
 	}
 
+	public boolean isReturningAllColumns() {
+		return returningAllColumns;
+	}
+
+	public void setReturningAllColumns(boolean returningAllColumns) {
+		this.returningAllColumns = returningAllColumns;
+	}
+
+	public List<SelectExpressionItem> getReturningExpressionList() {
+		return returningExpressionList;
+	}
+
+	public void setReturningExpressionList(List<SelectExpressionItem> returningExpressionList) {
+		this.returningExpressionList = returningExpressionList;
+	}
+
 	@Override
 	public String toString() {
 		StringBuilder b = new StringBuilder("UPDATE ");
@@ -210,6 +229,13 @@ public String toString() {
 		if (limit != null) {
 			b.append(limit);
 		}
+
+		if (isReturningAllColumns()) {
+			b.append(" RETURNING *");
+		} else if (getReturningExpressionList() != null) {
+			b.append(" RETURNING ").append(PlainSelect.getStringList(getReturningExpressionList(), true, false));
+		}
+
 		return b.toString();
 	}
 }

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

@@ -21,6 +21,8 @@
  */
 package net.sf.jsqlparser.util.deparser;
 
+import java.util.Iterator;
+
 import net.sf.jsqlparser.expression.Expression;
 import net.sf.jsqlparser.expression.ExpressionVisitor;
 import net.sf.jsqlparser.schema.Column;
@@ -31,7 +33,7 @@
 import net.sf.jsqlparser.statement.select.SelectVisitor;
 import net.sf.jsqlparser.statement.select.OrderByVisitor;
 import net.sf.jsqlparser.statement.select.OrderByElement;
-
+import net.sf.jsqlparser.statement.select.SelectExpressionItem;
 /**
  * A class to de-parse (that is, tranform from JSqlParser hierarchy into a
  * string) an {@link net.sf.jsqlparser.statement.update.Update}
@@ -125,6 +127,17 @@ public void deParse(Update update) {
             new LimitDeparser(buffer).deParse(update.getLimit());
         }
 
+        if (update.isReturningAllColumns()) {
+            buffer.append(" RETURNING *");
+        } else if (update.getReturningExpressionList() != null) {
+            buffer.append(" RETURNING ");
+            for (Iterator<SelectExpressionItem> iter = update.getReturningExpressionList().iterator(); iter.hasNext();) {
+                buffer.append(iter.next().toString());
+                if (iter.hasNext()) {
+                    buffer.append(", ");
+                }
+            }
+        }
     }
 
     public ExpressionVisitor getExpressionVisitor() {

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

@@ -370,6 +370,7 @@ Update Update():
 	Limit limit = null;
 	List<OrderByElement> orderByElements;
 	boolean useColumnsBrackets = false;
+	List<SelectExpressionItem> returning = null;
 }
 {
     <K_UPDATE> table=TableWithAlias() { tables.add(table); } 
@@ -398,6 +399,12 @@ Update Update():
 
    [ orderByElements = OrderByElements() { update.setOrderByElements(orderByElements); } ]
    [ limit = PlainLimit() { update.setLimit(limit); } ]
+   [ <K_RETURNING> (
+              "*" { update.setReturningAllColumns(true); }
+              | returning=ListExpressionItem()
+              )
+       ]
+
    {
    		update.setColumns(columns);
    		update.setExpressions(expList);
@@ -406,6 +413,7 @@ Update Update():
 		update.setJoins(joins);
 		update.setSelect(select);
 		update.setUseColumnsBrackets(useColumnsBrackets);
+		update.setReturningExpressionList(returning);
 		return update;
    }
 }

src/test/java/net/sf/jsqlparser/test/update/UpdateTest.java

@@ -86,6 +86,22 @@ public void testUpdateWithOrderByAndLimit() throws JSQLParserException {
 		assertSqlCanBeParsedAndDeparsed("UPDATE tablename SET col = 'thing' WHERE id = 1 ORDER BY col LIMIT 10");
 	}
 
+	@Test
+	public void testUpdateWithReturningAll() throws JSQLParserException {
+		assertSqlCanBeParsedAndDeparsed("UPDATE tablename SET col = 'thing' WHERE id = 1 ORDER BY col LIMIT 10 RETURNING *");
+		assertSqlCanBeParsedAndDeparsed("UPDATE tablename SET col = 'thing' WHERE id = 1 RETURNING *");
+	}
+
+	@Test
+	public void testUpdateWithReturningList() throws JSQLParserException {
+		assertSqlCanBeParsedAndDeparsed("UPDATE tablename SET col = 'thing' WHERE id = 1 ORDER BY col LIMIT 10 RETURNING col_1, col_2, col_3");
+		assertSqlCanBeParsedAndDeparsed("UPDATE tablename SET col = 'thing' WHERE id = 1 RETURNING col_1, col_2, col_3");
+		assertSqlCanBeParsedAndDeparsed("UPDATE tablename SET col = 'thing' WHERE id = 1 ORDER BY col LIMIT 10 RETURNING col_1 AS Bar, col_2 AS Baz, col_3 AS Foo");
+		assertSqlCanBeParsedAndDeparsed("UPDATE tablename SET col = 'thing' WHERE id = 1 RETURNING col_1 AS Bar, col_2 AS Baz, col_3 AS Foo");
+		assertSqlCanBeParsedAndDeparsed("UPDATE tablename SET col = 'thing' WHERE id = 1 RETURNING ABS(col_1) AS Bar, ABS(col_2), col_3 AS Foo");
+	}
+
+
 	@Test(expected = JSQLParserException.class)
 	public void testUpdateDoesNotAllowLimitOffset() throws JSQLParserException {
 		String statement = "UPDATE table1 A SET A.columna = 'XXX' WHERE A.cod_table = 'YYY' LIMIT 3,4";