fix: parse INTERVAL column type with time-unit qualifier

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

@@ -10705,6 +10705,8 @@ ColDataType ColDataType():
     Token prefix = null;
     Token tk = null;
     Token tk2 = null;
+    Token intervalUnit = null;
+    Token intervalTo = null;
     String schema;
     String type="";
     List<String> argumentsStringList = new ArrayList<String>();
@@ -10753,6 +10755,9 @@ ColDataType ColDataType():
 			| tk=<K_NAME>
         ) { schema = tk.image; }
 
+        // INTERVAL qualifier such as `interval hour to minute` or `interval year` (PG/Oracle column type)
+        [ LOOKAHEAD({ tk.kind == K_INTERVAL && getToken(1).kind == K_DATE_LITERAL }) intervalUnit=<K_DATE_LITERAL> { schema += " " + intervalUnit.image; }
+            [ intervalTo=<K_TO> intervalUnit=<K_DATE_LITERAL> { schema += " " + intervalTo.image + " " + intervalUnit.image; } ] ]
         [ LOOKAHEAD(2) "."  arrayType = ColDataType()  { schema += "." + arrayType.toString(); } ]
         { colDataType.setDataType(schema); }
     )

src/test/java/net/sf/jsqlparser/statement/create/table/ColDataTypeTest.java

@@ -14,6 +14,7 @@
 import org.junit.jupiter.api.Test;
 
 import static net.sf.jsqlparser.test.TestUtils.assertSqlCanBeParsedAndDeparsed;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 class ColDataTypeTest {
     @Test
@@ -57,4 +58,26 @@ void testStruct() throws JSQLParserException {
                         "  );\n";
         assertSqlCanBeParsedAndDeparsed(sqlStr, true);
     }
+
+    // PG/Oracle allow an INTERVAL column type carrying a time-unit qualifier,
+    // e.g. `interval hour to minute`. Previously the qualifier was not consumed
+    // as part of the data type, so parsing failed with "Encountered ... <K_DATE_LITERAL>".
+    @Test
+    void testIntervalQualifierIssue1728() throws JSQLParserException {
+        String sqlStr = "CREATE TABLE films (code char(5), len interval hour to minute)";
+        CreateTable create = (CreateTable) assertSqlCanBeParsedAndDeparsed(sqlStr, true);
+
+        // The qualifier must be attached to the column's data type, not parsed as an
+        // alias or left unconsumed.
+        ColumnDefinition len = create.getColumnDefinitions().stream()
+                .filter(c -> c.getColumnName().equalsIgnoreCase("len"))
+                .findFirst()
+                .orElseThrow();
+        assertEquals("interval hour to minute", len.getColDataType().getDataType());
+    }
+
+    @Test
+    void testIntervalQualifierYearToMonthIssue1728() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("CREATE TABLE t (a interval year to month)", true);
+    }
 }