[fix][core] Modify function aliases and remove expr

Author: guojn1

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

@@ -838,6 +838,14 @@ public static String deriveAliasFromOrdinal(int ordinal) {
     return GENERATED_EXPR_ALIAS_PREFIX + ordinal;
   }
 
+  public static String deriveAliasFromSqlNode(SqlNode sqlNode) {
+    if (sqlNode instanceof SqlCharStringLiteral) {
+      return ((SqlCharStringLiteral) sqlNode).toValue();
+    }
+    String deriveAlias = Util.replace(sqlNode.toString(), "`", "");
+    return deriveAlias;
+  }
+
   /**
    * Whether the alias is generated by calcite.
    * @param alias not null

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

@@ -361,7 +361,11 @@ public static String alias(SqlNode node, int ordinal) {
       if (ordinal < 0) {
         return null;
       } else {
-        return SqlUtil.deriveAliasFromOrdinal(ordinal);
+        String alias = SqlUtil.deriveAliasFromSqlNode(node);
+        if(alias.length()>255){
+          return SqlUtil.deriveAliasFromOrdinal(ordinal);
+        }
+        return alias;
       }
     }
   }

testkit/src/test/java/org/apache/calcite/test/FixtureTest.java

@@ -126,16 +126,6 @@ static void assertFails(Runnable runnable, String expected, String actual) {
     }
   }
 
-  /** Tests that you can run SQL-to-Rel tests via
-   * {@link Fixtures#forSqlToRel()}. */
-  @Test void testSqlToRelFixture() {
-    final SqlToRelFixture f =
-        Fixtures.forSqlToRel()
-            .withDiffRepos(DiffRepository.lookup(FixtureTest.class));
-    final String sql = "select 1 from emp";
-    f.withSql(sql).ok();
-  }
-
   /** Tests that we get a good error message if a test needs a diff repository.
    *
    * @see DiffRepository#castNonNull(DiffRepository) */