Expose editable ALTER column identity actions

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

@@ -9,6 +9,9 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import java.util.Collections;
+import java.util.List;
+
 import java.util.Objects;
 import net.sf.jsqlparser.statement.create.table.ConstraintAttributes;
 import net.sf.jsqlparser.statement.create.table.ConstraintKind;
@@ -30,6 +33,11 @@ public void setAttributes(ConstraintAttributes attributes) {
         this.attributes = Objects.requireNonNull(attributes, "attributes");
     }
 
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return Collections.emptyList();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;

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

@@ -444,6 +444,35 @@ public List<ColumnDefaultAction> getColumnDefaults() {
         return Collections.unmodifiableList(columnSetDefaultList);
     }
 
+    /**
+     * Returns active ALTER COLUMN identity actions without treating them as data-type changes. The
+     * list is an unmodifiable membership snapshot; its entries are the original mutable column
+     * nodes. Request a new list after adding, removing or changing actions. Subclasses that render
+     * a different body override this method to exclude inactive inherited column definitions.
+     */
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        if (hasExplicitConstraintHeader() || isRenameOperation() || hasAlterColumnValueActions()) {
+            return Collections.emptyList();
+        }
+        return getColumnIdentityActionsFromDefinitions();
+    }
+
+    /** Returns identity actions when this body's general column-definition branch is active. */
+    protected List<ColumnIdentityAction> getColumnIdentityActionsFromDefinitions() {
+        if (operation != AlterOperation.ALTER || colDataTypeList == null
+                || columnName != null || commentText != null) {
+            return Collections.emptyList();
+        }
+        List<ColumnIdentityAction> actions = new ArrayList<>();
+        for (ColumnDataType column : colDataTypeList) {
+            if (column.getIdentityAlterations() != null
+                    && !column.getIdentityAlterations().isEmpty()) {
+                actions.add(column);
+            }
+        }
+        return Collections.unmodifiableList(actions);
+    }
+
     public void addColSetVisibility(ColumnSetVisibility columnSetVisibility) {
         if (columnSetVisibilityList == null) {
             columnSetVisibilityList = new ArrayList<>();
@@ -994,10 +1023,7 @@ protected void appendBody(StringBuilder b) {
             b.append(optionalSpecifier);
         } else if (hasExplicitConstraintHeader()) {
             toStringConstraintAlter(b);
-        } else if (operation == AlterOperation.ALTER
-                && (columnDropDefaultList != null && !columnDropDefaultList.isEmpty()
-                        || columnSetDefaultList != null && !columnSetDefaultList.isEmpty()
-                        || columnSetVisibilityList != null && !columnSetVisibilityList.isEmpty())) {
+        } else if (hasAlterColumnValueActions()) {
             toStringAlterColumn(b);
         } else if (isSimpleKeywordOperation()) {
             toStringSimpleKeyword(b);
@@ -1014,6 +1040,13 @@ protected void appendBody(StringBuilder b) {
         }
     }
 
+    private boolean hasAlterColumnValueActions() {
+        return operation == AlterOperation.ALTER
+                && (columnDropDefaultList != null && !columnDropDefaultList.isEmpty()
+                        || columnSetDefaultList != null && !columnSetDefaultList.isEmpty()
+                        || columnSetVisibilityList != null && !columnSetVisibilityList.isEmpty());
+    }
+
     /**
      * Appends the common tail (parameters, index comment) shared by all ALTER expressions.
      */
@@ -1711,7 +1744,8 @@ public void setHasEqualForCollate(boolean hasEqualForCollate) {
         this.hasEqualForCollate = hasEqualForCollate;
     }
 
-    public static final class ColumnDataType extends ColumnDefinition {
+    public static final class ColumnDataType extends ColumnDefinition
+            implements ColumnIdentityAction {
 
         private final boolean withType;
         private boolean useSetData;
@@ -1739,10 +1773,12 @@ public void setUsingExpression(Expression usingExpression) {
             this.usingExpression = usingExpression;
         }
 
+        @Override
         public List<IdentityAlteration> getIdentityAlterations() {
             return identityAlterations;
         }
 
+        @Override
         public void setIdentityAlterations(List<IdentityAlteration> identityAlterations) {
             this.identityAlterations =
                     identityAlterations == null ? null : new ArrayList<>(identityAlterations);

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

@@ -9,6 +9,9 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import java.util.Collections;
+import java.util.List;
+
 import net.sf.jsqlparser.statement.create.table.ConstraintKind;
 
 /**
@@ -17,6 +20,11 @@
  */
 public class AlterExpressionCharset extends AlterExpression {
 
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return Collections.emptyList();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;

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

@@ -9,6 +9,7 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import java.util.List;
 
 import net.sf.jsqlparser.statement.select.PlainSelect;
 import net.sf.jsqlparser.statement.create.table.ConstraintKind;
@@ -18,6 +19,11 @@
  * DROP INDEX/KEY, DROP PRIMARY KEY, DROP UNIQUE, DROP FOREIGN KEY, and DROP PARTITION.
  */
 public class AlterExpressionDrop extends AlterExpression {
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return getColumnIdentityActionsFromDefinitions();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;

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

@@ -9,6 +9,8 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import java.util.Collections;
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Consumer;
@@ -28,6 +30,11 @@ public List<OrderByElement> getOrderByElements() {
         return orderByElements;
     }
 
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return Collections.emptyList();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;

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

@@ -9,6 +9,7 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+
 import java.util.AbstractList;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -264,6 +265,11 @@ public void setCoalescePartitionCount(Integer coalescePartitionCount) {
         }
     }
 
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return Collections.emptyList();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;

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

@@ -9,6 +9,9 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import java.util.Collections;
+import java.util.List;
+
 import net.sf.jsqlparser.statement.create.table.IndexOption;
 import net.sf.jsqlparser.statement.create.table.KeyElement;
 import java.util.Iterator;
@@ -31,6 +34,11 @@ public AlterExpressionPrimaryKey() {
         setConstraint(new KeyConstraint().withType("PRIMARY KEY"));
     }
 
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return Collections.emptyList();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;

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

@@ -9,6 +9,9 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import java.util.Collections;
+import java.util.List;
+
 import net.sf.jsqlparser.statement.create.table.ConstraintKind;
 
 /**
@@ -42,6 +45,11 @@ public void setTargetName(String name) {
         setColumnName(name);
     }
 
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return Collections.emptyList();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;

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

@@ -9,6 +9,9 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import java.util.Collections;
+import java.util.List;
+
 import net.sf.jsqlparser.statement.create.table.TableOption;
 import net.sf.jsqlparser.statement.create.table.ConstraintKind;
 
@@ -33,6 +36,11 @@ public void setStructuredTableOption(TableOption option) {
         super.setUseEqual(false);
     }
 
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return Collections.emptyList();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;

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

@@ -9,6 +9,8 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import java.util.Collections;
+
 import java.util.List;
 import java.util.function.Consumer;
 import net.sf.jsqlparser.expression.Expression;
@@ -40,6 +42,11 @@ public StringBuilder appendTo(StringBuilder builder, Consumer<Expression> expres
         return builder;
     }
 
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return Collections.emptyList();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;

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

@@ -0,0 +1,28 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2026 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.statement.alter;
+
+import java.util.List;
+
+/**
+ * An ALTER COLUMN target and its ordered identity alterations. Obtain active column actions through
+ * {@link AlterExpression#getColumnIdentityActions()}; edits update the existing statement model.
+ */
+public interface ColumnIdentityAction {
+    String getColumnName();
+
+    void setColumnName(String columnName);
+
+    /** Returns the mutable, ordered alterations, or null when this column has none. */
+    List<IdentityAlteration> getIdentityAlterations();
+
+    /** Replaces the alterations; null restores the column's ordinary definition rendering. */
+    void setIdentityAlterations(List<IdentityAlteration> identityAlterations);
+}

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

@@ -45,20 +45,60 @@ public void setIdentityDefinition(IdentityDefinition identityDefinition) {
         this.identityDefinition = identityDefinition;
     }
 
+    /**
+     * Returns ADD's definition mode or SET GENERATED's mode. An ADD without a definition returns
+     * null; no definition is created by reading it.
+     */
     public IdentityDefinition.GenerationMode getGenerationMode() {
-        return generationMode;
+        return kind == Kind.ADD
+                ? identityDefinition == null ? null : identityDefinition.getGenerationMode()
+                : generationMode;
     }
 
+    /**
+     * Updates ADD's existing definition or SET GENERATED's mode. A non-null ADD mode creates a
+     * definition when absent; a null mode never creates one. Other kinds retain the value as
+     * inactive metadata and do not render it.
+     */
     public void setGenerationMode(IdentityDefinition.GenerationMode generationMode) {
-        this.generationMode = generationMode;
+        if (kind == Kind.ADD) {
+            if (identityDefinition != null) {
+                identityDefinition.setGenerationMode(generationMode);
+            } else if (generationMode != null) {
+                identityDefinition = new IdentityDefinition(generationMode);
+            }
+        } else {
+            this.generationMode = generationMode;
+        }
     }
 
+    /**
+     * Returns ADD's definition parameters or SET_PARAMETER's parameters. The returned list belongs
+     * to the active payload and can be edited directly; an omitted list is null.
+     */
     public List<Sequence.Parameter> getParameters() {
-        return parameters;
+        return kind == Kind.ADD
+                ? identityDefinition == null ? null : identityDefinition.getParameters()
+                : parameters;
     }
 
+    /**
+     * Updates ADD's definition parameters or SET_PARAMETER's parameters. A non-null ADD list
+     * creates a BY DEFAULT definition when absent; a null list never creates one. Other kinds
+     * retain the value as inactive metadata and do not render it.
+     */
     public void setParameters(List<Sequence.Parameter> parameters) {
-        this.parameters = parameters == null ? null : new ArrayList<>(parameters);
+        if (kind == Kind.ADD) {
+            if (identityDefinition == null && parameters != null) {
+                identityDefinition =
+                        new IdentityDefinition(IdentityDefinition.GenerationMode.BY_DEFAULT);
+            }
+            if (identityDefinition != null) {
+                identityDefinition.setParameters(parameters);
+            }
+        } else {
+            this.parameters = parameters == null ? null : new ArrayList<>(parameters);
+        }
     }
 
     /** Returns the restart value, or null for a bare RESTART using the sequence start value. */

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

@@ -9,6 +9,7 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+
 import java.util.Collections;
 import java.util.List;
 import java.util.function.Consumer;
@@ -240,6 +241,11 @@ public void setResetOptions(List<String> resetOptions) {
         this.resetOptions = resetOptions;
     }
 
+    @Override
+    public List<ColumnIdentityAction> getColumnIdentityActions() {
+        return Collections.emptyList();
+    }
+
     @Override
     public boolean hasActiveTableDefinition() {
         return false;