feat(parser): allow COLLATE in ORDER BY clauses (issue #2245) (#2277)

* add collate parsing and tests for order by

* rm unnecessary test

* add quoted identifier for "und-x-icu"

Author: ldaIas

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

@@ -5204,9 +5204,11 @@ OrderByElement OrderByElement():
 {
     OrderByElement orderByElement = new OrderByElement();
     Expression columnReference = null;
+    Token collateToken = null;
 }
 {
     columnReference = Expression()
+    [ LOOKAHEAD(<K_COLLATE>) <K_COLLATE> (collateToken=<S_CHAR_LITERAL> | collateToken=<S_QUOTED_IDENTIFIER>) { columnReference = new CollateExpression(columnReference, collateToken.image); } ]
     [ LOOKAHEAD(2) ( <K_ASC> | (<K_DESC> { orderByElement.setAsc(false); } )) { orderByElement.setAscDescPresent(true); }  ]
     [ LOOKAHEAD(2) <K_NULLS>
         [ LOOKAHEAD(2) (
@@ -6503,7 +6505,7 @@ Expression PrimaryExpression() #PrimaryExpression:
     )
 
     [
-        LOOKAHEAD(2) <K_COLLATE> token=<S_IDENTIFIER> { retval = new CollateExpression(retval, token.image); }
+        LOOKAHEAD(2) <K_COLLATE> (token=<S_CHAR_LITERAL> | token=<S_QUOTED_IDENTIFIER> | token=<S_IDENTIFIER>) { retval = new CollateExpression(retval, token.image); }
     ]
 
     [

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

@@ -0,0 +1,33 @@
+package net.sf.jsqlparser.statement.select;
+
+import static net.sf.jsqlparser.test.TestUtils.assertSqlCanBeParsedAndDeparsed;
+
+import net.sf.jsqlparser.JSQLParserException;
+import org.junit.jupiter.api.Test;
+
+public class OrderByCollateTest {
+
+    @Test
+    public void testOrderByWithCollate() throws JSQLParserException {
+        String sql = "SELECT * FROM a ORDER BY CAST(a.xyz AS TEXT) COLLATE \"und-x-icu\" ASC NULLS FIRST";
+        assertSqlCanBeParsedAndDeparsed(sql);
+    }
+
+    @Test
+    public void testOrderByWithCollateSimple() throws JSQLParserException {
+        String sql = "SELECT * FROM a ORDER BY col COLLATE \"C\" ASC";
+        assertSqlCanBeParsedAndDeparsed(sql);
+    }
+
+    @Test
+    public void testOrderByWithCollateMultiple() throws JSQLParserException {
+        String sql = "SELECT * FROM a ORDER BY col1 COLLATE \"C\" ASC, col2 COLLATE \"POSIX\" DESC";
+        assertSqlCanBeParsedAndDeparsed(sql);
+    }
+
+    @Test
+    public void testOrderByWithCollateAndNulls() throws JSQLParserException {
+        String sql = "SELECT * FROM a ORDER BY col COLLATE \"C\" DESC NULLS LAST";
+        assertSqlCanBeParsedAndDeparsed(sql);
+    }
+}