fix: preserve PostgreSQL identity sequence names

src/main/java/net/sf/jsqlparser/schema/Sequence.java

@@ -187,7 +187,7 @@ public Sequence addParameters(Collection<? extends Parameter> parameters) {
      * The available parameters to a sequence
      */
     public enum ParameterType {
-        INCREMENT_BY, INCREMENT, START_WITH, START, RESTART_WITH, MAXVALUE, NOMAXVALUE, MINVALUE, NOMINVALUE, CYCLE, NOCYCLE, CACHE, NOCACHE, ORDER, NOORDER, KEEP, NOKEEP, SESSION, GLOBAL, NO_MINVALUE, NO_MAXVALUE, NO_CYCLE;
+        INCREMENT_BY, INCREMENT, START_WITH, START, RESTART_WITH, MAXVALUE, NOMAXVALUE, MINVALUE, NOMINVALUE, CYCLE, NOCYCLE, CACHE, NOCACHE, ORDER, NOORDER, KEEP, NOKEEP, SESSION, GLOBAL, NO_MINVALUE, NO_MAXVALUE, NO_CYCLE, SEQUENCE_NAME;
 
         public static ParameterType from(String type) {
             return Enum.valueOf(ParameterType.class, type.toUpperCase(Locale.ROOT));
@@ -201,6 +201,7 @@ public static class Parameter implements java.io.Serializable {
 
         private final ParameterType option;
         private Long value;
+        private Sequence sequenceName;
 
         public Parameter(ParameterType option) {
             this.option = option;
@@ -214,6 +215,20 @@ public ParameterType getOption() {
             return option;
         }
 
+        /** The sequence named by an identity declaration's SEQUENCE NAME option. */
+        public Sequence getSequenceName() {
+            return sequenceName;
+        }
+
+        public void setSequenceName(Sequence sequenceName) {
+            this.sequenceName = sequenceName;
+        }
+
+        public Parameter withSequenceName(Sequence sequenceName) {
+            setSequenceName(sequenceName);
+            return this;
+        }
+
         @Override
         public String toString() {
             return formatParameter();
@@ -225,6 +240,8 @@ public void setValue(Long value) {
 
         public String formatParameter() {
             switch (option) {
+                case SEQUENCE_NAME:
+                    return "SEQUENCE NAME " + sequenceName.getFullyQualifiedName();
                 case INCREMENT_BY:
                     return prefix("INCREMENT BY");
                 case INCREMENT:

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

@@ -14217,7 +14217,9 @@ IdentityDefinition IdentityDefinition():
     Token token;
     IdentityDefinition.GenerationMode mode;
     IdentityDefinition identity;
-    List<Sequence.Parameter> parameters;
+    List<Sequence.Parameter> parameters = new ArrayList<Sequence.Parameter>();
+    Sequence.Parameter parameter;
+    Sequence sequenceName;
 }
 {
     token=<S_IDENTIFIER> {
@@ -14226,8 +14228,18 @@ IdentityDefinition IdentityDefinition():
     ( <K_ALWAYS> { mode = IdentityDefinition.GenerationMode.ALWAYS; }
         | <K_BY> <K_DEFAULT> { mode = IdentityDefinition.GenerationMode.BY_DEFAULT; } )
     <K_AS> <K_IDENTITY> { identity = new IdentityDefinition(mode); }
-    [ LOOKAHEAD(2) "(" parameters=SequenceParameters() ")" {
-        requireDdlSyntax(!parameters.isEmpty(), "Expected an identity sequence parameter");
+    [ LOOKAHEAD(1) "("
+        (
+            (
+                LOOKAHEAD(<K_SEQUENCE> <K_NAME>)
+                <K_SEQUENCE> <K_NAME> sequenceName=Sequence()
+                { parameter = new Sequence.Parameter(Sequence.ParameterType.SEQUENCE_NAME)
+                        .withSequenceName(sequenceName); }
+                | parameter=SequenceParameter()
+            )
+            { parameters.add(parameter); }
+        )+
+        ")" {
         identity.setParameters(parameters);
     } ]
     { return identity; }

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

@@ -0,0 +1,76 @@
+/*-
+ * #%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.create;
+
+import static org.junit.jupiter.api.Assertions.*;
+import net.sf.jsqlparser.JSQLParserException;
+import net.sf.jsqlparser.parser.AbstractJSqlParser.Dialect;
+import net.sf.jsqlparser.parser.CCJSqlParserUtil;
+import net.sf.jsqlparser.schema.Sequence;
+import net.sf.jsqlparser.statement.Statement;
+import net.sf.jsqlparser.statement.alter.Alter;
+import net.sf.jsqlparser.statement.create.table.CreateTable;
+import net.sf.jsqlparser.statement.create.table.IdentityDefinition;
+import net.sf.jsqlparser.util.deparser.StatementDeParser;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+class IdentitySequenceNameTest {
+    @ParameterizedTest
+    @ValueSource(strings = {"ids", "public.ids", "\"schema.name\".\"seq.name\""})
+    void sharesIdentityOptionsAcrossCreateAndAlter(String name) throws JSQLParserException {
+        String definition = "GENERATED BY DEFAULT AS IDENTITY (START 4 SEQUENCE NAME " + name
+                + " CACHE 2 NO CYCLE)";
+        CreateTable create = (CreateTable) parse("CREATE TABLE t (id INT " + definition + ")");
+        IdentityDefinition identity = create.getColumnDefinitions().get(0).getColumnOptions().get(0)
+                .getIdentityDefinition();
+        Alter alter = (Alter) parse("ALTER TABLE t ALTER COLUMN id ADD " + definition);
+        IdentityDefinition altered = alter.getAlterExpressions().get(0).getColDataTypeList().get(0)
+                .getIdentityAlterations().get(0).getIdentityDefinition();
+        for (IdentityDefinition current : new IdentityDefinition[] {identity, altered}) {
+            assertEquals(4, current.getParameters().size());
+            Sequence.Parameter named = current.getParameters().get(1);
+            assertEquals(Sequence.ParameterType.SEQUENCE_NAME, named.getOption());
+            assertEquals(name, named.getSequenceName().getFullyQualifiedName());
+            assertNull(named.getValue());
+            named.getSequenceName().setName("renamed");
+        }
+        assertTrue(create.toString().contains("renamed"));
+        assertTrue(alter.toString().contains("renamed"));
+        roundTrip(create);
+        roundTrip(alter);
+    }
+
+    @Test
+    void preservesNameOnlyAndDoesNotExtendStandaloneSequenceOptions() throws JSQLParserException {
+        String sql = "CREATE TABLE t (id INT GENERATED ALWAYS AS IDENTITY (SEQUENCE NAME ids))";
+        assertEquals(sql, parse(sql).toString());
+        roundTrip(parse(sql));
+        for (String invalid : new String[] {
+                "CREATE TABLE t (id INT GENERATED ALWAYS AS IDENTITY (SEQUENCE NAME))",
+                "CREATE TABLE t (id INT GENERATED ALWAYS AS IDENTITY ())",
+                "CREATE SEQUENCE ids SEQUENCE NAME other_ids",
+                "ALTER TABLE t ALTER COLUMN id SET SEQUENCE NAME other_ids"}) {
+            assertThrows(JSQLParserException.class, () -> parse(invalid), invalid);
+        }
+    }
+
+    private static Statement parse(String sql) throws JSQLParserException {
+        return CCJSqlParserUtil.parse(sql, p -> p.withDialect(Dialect.POSTGRESQL));
+    }
+
+    private static void roundTrip(Statement statement) throws JSQLParserException {
+        StringBuilder out = new StringBuilder();
+        statement.accept(new StatementDeParser(out));
+        assertEquals(statement.toString(), out.toString());
+        assertEquals(out.toString(), parse(out.toString()).toString());
+    }
+}