fix: follow active rename precedence in constraint inspection

Signed-off-by: minleejae <mmj9808@gmail.com>

Author: minleejae

src/main/java/net/sf/jsqlparser/statement/alter/AlterExpression.java

@@ -600,6 +600,10 @@ public Index.Kind getConstraintKind() {
         if (operation == null) {
             return Index.Kind.OTHER;
         }
+        if (isRenameOperation() && !(constraintType != null && constraintSymbol != null
+                && (operation == AlterOperation.ADD || operation == AlterOperation.ALTER))) {
+            return Index.Kind.OTHER;
+        }
         switch (operation) {
             case DROP_PRIMARY_KEY:
             case ALTER_PRIMARY_KEY:

src/main/java/net/sf/jsqlparser/statement/alter/AlterExpressionDrop.java

@@ -25,10 +25,13 @@ public Index.Kind getConstraintKind() {
         }
         switch (getOperation()) {
             case DROP_PRIMARY_KEY:
+                return Index.Kind.PRIMARY_KEY;
             case DROP_UNIQUE:
+                return Index.Kind.UNIQUE;
             case DROP_FOREIGN_KEY:
+                return Index.Kind.FOREIGN_KEY;
             case DROP_CHECK:
-                return super.getConstraintKind();
+                return Index.Kind.CHECK;
             default:
                 return Index.Kind.OTHER;
         }

src/test/java/net/sf/jsqlparser/statement/create/ConstraintInspectionTest.java

@@ -272,6 +272,33 @@ void dropColumnActionDoesNotBecomeAPrimaryKeyDeclarationFromStaleFields() throws
         assertEquals(before, action.toString());
     }
 
+    @ParameterizedTest
+    @ValueSource(strings = {"DROP PRIMARY KEY", "DROP FOREIGN KEY fk", "DROP CHECK ck"})
+    void distinguishesBaseRenamePrecedenceFromSpecializedDropRendering(String sql)
+            throws Exception {
+        AlterExpression drop = action("ALTER TABLE t " + sql, Dialect.MYSQL);
+        Kind expected = drop.getConstraintKind();
+        String before = drop.toString();
+        Index oldName = new Index().withName("old_name");
+        Index newName = new Index().withName("new_name");
+        drop.setOldIndex(oldName);
+        drop.setIndex(newName);
+        assertEquals(expected, drop.getConstraintKind());
+        assertEquals(before, drop.toString());
+
+        AlterExpression base = new AlterExpression().withOperation(drop.getOperation());
+        base.setOldIndex(oldName);
+        base.setIndex(newName);
+        assertTrue(base.toString().startsWith("RENAME"));
+        assertEquals(Kind.OTHER, base.getConstraintKind());
+
+        base.setOperation(AlterOperation.ALTER);
+        base.setConstraintType("CHECK");
+        base.setConstraintSymbol("ck");
+        assertTrue(base.toString().startsWith("ALTER CHECK ck"));
+        assertEquals(Kind.CHECK, base.getConstraintKind());
+    }
+
     @Test
     void supportsLegacyOnlyKeysWithoutMistakingDropColumnsForPrimaryKeys() {
         AlterExpression legacy = new AlterExpression().withOperation(AlterOperation.ADD)