fixes #849

README.md

@@ -66,6 +66,10 @@ Also I would like to know about needed examples or documentation stuff.
 
 ## Extensions in the latest SNAPSHOT version 3.1
 
+* introduced more positions for *!* instead of *NOT*
+* allowed more complex expressions within *if* function
+* introduced multicolumn alias like *select * from mytab as tab(c1, c2)*
+** additional type definition is possible (issue #849)
 
 ## Extensions of JSqlParser releases
 

src/main/java/net/sf/jsqlparser/expression/Alias.java

@@ -9,10 +9,15 @@
  */
 package net.sf.jsqlparser.expression;
 
+import java.util.List;
+import java.util.Objects;
+import net.sf.jsqlparser.statement.create.table.ColDataType;
+
 public class Alias {
 
     private String name;
     private boolean useAs = true;
+    private List<AliasColumn> aliasColumns;
 
     public Alias(String name) {
         this.name = name;
@@ -39,8 +44,48 @@ public void setUseAs(boolean useAs) {
         this.useAs = useAs;
     }
 
+    public List<AliasColumn> getAliasColumns() {
+        return aliasColumns;
+    }
+
+    public void setAliasColumns(List<AliasColumn> aliasColumns) {
+        this.aliasColumns = aliasColumns;
+    }
+
     @Override
     public String toString() {
-        return (useAs ? " AS " : " ") + name;
+        String alias = (useAs ? " AS " : " ") + name;
+
+        if (aliasColumns != null && !aliasColumns.isEmpty()) {
+            String ac = "";
+            for (AliasColumn col : aliasColumns) {
+                if (ac.length() > 0) {
+                    ac += ", ";
+                }
+                ac += col.name;
+                if (col.colDataType != null) {
+                    ac += " " + col.colDataType.toString();
+                }
+            }
+            alias += "(" + ac + ")";
+        }
+
+        return alias;
+    }
+
+    public static class AliasColumn {
+
+        public final String name;
+        public final ColDataType colDataType;
+
+        public AliasColumn(String name, ColDataType colDataType) {
+            Objects.requireNonNull(name);
+            this.name = name;
+            this.colDataType = colDataType;
+        }
+
+        public AliasColumn(String name) {
+            this(name, null);
+        }
     }
 }

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

@@ -184,7 +184,6 @@ public void visit(SelectExpressionItem selectExpressionItem) {
         if (selectExpressionItem.getAlias() != null) {
             buffer.append(selectExpressionItem.getAlias().toString());
         }
-
     }
 
     @Override

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

@@ -1454,11 +1454,22 @@ AllTableColumns AllTableColumns():
 Alias Alias():
 { String name = null;
   Token token = null;
-  boolean useAs = false; }
+  boolean useAs = false; 
+  Alias alias;
+  String colname;
+  ColDataType colDataType = null;
+}
 {
     [<K_AS> { useAs = true; } ] 
 	( name=RelObjectName() | token=<S_CHAR_LITERAL> { name=token.image; } )
-   { return new Alias(name,useAs); }
+	{ alias = new Alias(name,useAs); }
+
+	[ LOOKAHEAD(2) "(" { List<Alias.AliasColumn> list = new ArrayList<Alias.AliasColumn>(); }
+		colname = RelObjectName() [ colDataType = ColDataType() ] { list.add(new Alias.AliasColumn(colname, colDataType)); }   
+		("," { colDataType=null; } colname = RelObjectName() [ colDataType = ColDataType()] { list.add(new Alias.AliasColumn(colname, colDataType)); } )*
+	")" { alias.setAliasColumns(list); } ]
+
+    { return alias; }
 }
 
 MySQLIndexHint MySQLIndexHint():

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

@@ -3829,4 +3829,14 @@ public void testIssue848_3() throws JSQLParserException {
     public void testIssue848_4() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed("select c1 from T1 where someFunc(select f1 from t2 where t2.id = T1.key) = 10", true);
     }
+
+    @Test
+    public void testMultiColumnAliasIssue849() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT * FROM mytable AS mytab2(col1, col2)");
+    }
+
+    @Test
+    public void testMultiColumnAliasIssue849_2() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT * FROM crosstab('select rowid, attribute, value from ct where attribute = ''att2'' or attribute = ''att3'' order by 1,2') AS ct(row_name text, category_1 text, category_2 text, category_3 text)");
+    }
 }