fix: omit inactive column defaults from shared access

Signed-off-by: minleejae <mmj9808@gmail.com>
manticore-projects · Oct 11, 2026 · Oct 1, 2026 · Oct 1, 2026 · Oct 1, 2026 · b2614e408d133efeecf50e044b8779d8609f13b5
commit b2614e408d133efeecf50e044b8779d8609f13b5
diff --git a/src/main/java/net/sf/jsqlparser/statement/alter/AlterExpression.java b/src/main/java/net/sf/jsqlparser/statement/alter/AlterExpression.java
@@ -426,6 +426,7 @@ public List<ColumnSetDefault> getColumnSetDefaultList() {
      */
     public List<ColumnDefaultAction> getColumnDefaults() {
         if (operation != AlterOperation.ALTER || columnSetDefaultList == null
+                || constraintType != null && constraintSymbol != null
                 || columnDropDefaultList != null && !columnDropDefaultList.isEmpty()) {
             return Collections.emptyList();
         }

diff --git a/src/main/java/net/sf/jsqlparser/util/deparser/AlterDeParser.java b/src/main/java/net/sf/jsqlparser/util/deparser/AlterDeParser.java
@@ -84,9 +84,7 @@ private void deParseAction(AlterExpression action) {
             deParseTail(action);
             return;
         }
-        if (action.getOperation() == net.sf.jsqlparser.statement.alter.AlterOperation.ALTER
-                && action.getColumnSetDefaultList() != null
-                && !action.getColumnSetDefaultList().isEmpty()) {
+        if (!action.getColumnDefaults().isEmpty()) {
             action.appendColumnActionTo(builder,
                     expression -> expression.accept(expressionVisitor, null));
             return;

diff --git a/src/site/sphinx/usage.rst b/src/site/sphinx/usage.rst
@@ -346,6 +346,37 @@ bare ``RESTART``, which uses the sequence's configured start value. Call
 ``new IdentityAlteration(Kind.RESTART).withRestartWith(20L)``.
 
 
+Column defaults on tables and views
+-----------------------------------
+
+``AlterExpression.getColumnDefaults()`` exposes active ``SET DEFAULT`` actions
+through ``ColumnDefaultAction`` for both tables and views. The returned list is
+read-only, but its entries are the original mutable AST objects:
+
+.. code-block:: java
+
+    for (String objectType : List.of("TABLE", "VIEW")) {
+        Statement statement = CCJSqlParserUtil.parse(
+                "ALTER " + objectType + " t ALTER COLUMN a SET DEFAULT 1",
+                parser -> parser.withDialect(Dialect.POSTGRESQL));
+        List<? extends AlterExpression> actions = statement instanceof Alter
+                ? ((Alter) statement).getAlterExpressions()
+                : ((AlterRelation) statement).getActions();
+        for (AlterExpression action : actions) {
+            for (ColumnDefaultAction column : action.getColumnDefaults()) {
+                column.setDefaultExpression(new LongValue(42));
+            }
+        }
+        System.out.println(statement); // SET DEFAULT 42 for either object type
+    }
+
+``getColumnName()`` and ``setColumnName()`` access the affected column.
+``getDefaultExpression()`` exposes parsed expressions; ``getDefaultValue()``
+returns their SQL text. Existing ``ColumnSetDefault`` constructors still accept
+opaque strings, for which ``getDefaultExpression()`` returns ``null``.
+Replacing an expression also replaces any opaque value. Unrelated actions
+return an empty list.
+
 Structured column attributes
 ============================
 

diff --git a/src/test/java/net/sf/jsqlparser/statement/alter/ColumnDefaultActionTest.java b/src/test/java/net/sf/jsqlparser/statement/alter/ColumnDefaultActionTest.java
@@ -129,6 +129,28 @@ void inactiveRelationPropertiesDoNotAppearAsDefaults() {
         assertTrue(action.getColumnDefaults().isEmpty());
     }
 
+    @Test
+    void constraintAlterationTakesPrecedenceOverPreviouslySetDefaults() throws JSQLParserException {
+        Alter statement =
+                (Alter) CCJSqlParserUtil.parse("ALTER TABLE t ALTER COLUMN a SET DEFAULT 1");
+        AlterExpression action = statement.getAlterExpressions().get(0);
+        ColumnDefaultAction previousDefault = action.getColumnDefaults().get(0);
+        action.setConstraintType("CHECK");
+        action.setConstraintSymbol("c");
+        action.setEnforced(true);
+
+        assertTrue(action.getColumnDefaults().isEmpty());
+        assertEquals("ALTER TABLE t ALTER CHECK c ENFORCED", statement.toString());
+        StringBuilder sql = new StringBuilder();
+        statement.accept(new StatementDeParser(sql), null);
+        assertEquals(statement.toString(), sql.toString());
+        assertEquals(statement.toString(), CCJSqlParserUtil.parse(sql.toString()).toString());
+
+        action.setConstraintSymbol(null);
+        assertSame(previousDefault, action.getColumnDefaults().get(0));
+        roundTrip(statement);
+    }
+
     @Test
     void opaqueLegacyConstructorIsNotParsedOrPassedToAnExpressionVisitor() {
         ColumnSetDefault legacy = new ColumnSetDefault("a", "vendor_specific(?)::opaque");