feat(duckdb): support column rename

Closes #9506

crates/dbx-sql-schema/src/table_structure_sql/column_alter.rs

@@ -1020,6 +1020,20 @@ pub(super) fn build_sqlite_existing_column_sql(
     statements
 }
 
+pub(super) fn build_duckdb_existing_column_sql(table: &str, column: &EditableStructureColumn) -> Vec<String> {
+    let Some(original) = &column.original else {
+        return Vec::new();
+    };
+    if column.name == original.name {
+        return Vec::new();
+    }
+    vec![format!(
+        "ALTER TABLE {table} RENAME COLUMN {} TO {};",
+        quote_ident(StructureDialect::DuckDb, &original.name),
+        quote_ident(StructureDialect::DuckDb, &column.name)
+    )]
+}
+
 pub(super) fn build_questdb_existing_column_sql(table: &str, column: &EditableStructureColumn) -> Vec<String> {
     let Some(original) = &column.original else {
         return Vec::new();

crates/dbx-sql-schema/src/table_structure_sql/columns.rs

@@ -1,10 +1,11 @@
 use super::column_alter::{
     build_clickhouse_existing_column_sql, build_dameng_existing_column_sql, build_doris_existing_column_sql,
-    build_h2_existing_column_sql, build_informix_existing_column_sql, build_iris_existing_column_sql,
-    build_mysql_existing_column_clause, build_oracle_like_existing_column_sql, build_oscar_existing_column_sql,
-    build_postgres_existing_column_sql, build_questdb_existing_column_sql, build_sqlite_existing_column_sql,
-    build_sqlserver_existing_column_sql, build_xugu_existing_column_sql, dameng_drops_identity,
-    has_column_extra_change, has_existing_column_attribute_change, validate_dameng_existing_identity_change,
+    build_duckdb_existing_column_sql, build_h2_existing_column_sql, build_informix_existing_column_sql,
+    build_iris_existing_column_sql, build_mysql_existing_column_clause, build_oracle_like_existing_column_sql,
+    build_oscar_existing_column_sql, build_postgres_existing_column_sql, build_questdb_existing_column_sql,
+    build_sqlite_existing_column_sql, build_sqlserver_existing_column_sql, build_xugu_existing_column_sql,
+    dameng_drops_identity, has_column_extra_change, has_existing_column_attribute_change,
+    validate_dameng_existing_identity_change,
 };
 use super::column_format::{
     column_definition, has_dameng_identity, is_dameng_identity_compatible_type, is_mysql_character_data_type,
@@ -291,6 +292,7 @@ pub(super) fn build_column_sql(options: &TableStructureSqlOptions, warnings: &mu
                 warnings,
             )),
             StructureDialect::Sqlite => statements.extend(build_sqlite_existing_column_sql(&table, column, warnings)),
+            StructureDialect::DuckDb => statements.extend(build_duckdb_existing_column_sql(&table, column)),
             StructureDialect::Questdb => statements.extend(build_questdb_existing_column_sql(&table, column)),
             _ => warnings.push(format!("Editing existing columns is not supported for {database_label} yet.")),
         }

crates/dbx-sql-schema/src/table_structure_sql/tests.rs

@@ -4123,6 +4123,81 @@ fn builds_duckdb_create_table_statements() {
     );
 }
 
+#[cfg(feature = "duckdb-sidecar")]
+fn existing_duckdb_column(name: &str) -> EditableStructureColumn {
+    let mut existing = column(name);
+    existing.original = Some(ColumnInfo {
+        name: name.to_string(),
+        data_type: existing.data_type.clone(),
+        is_nullable: existing.is_nullable,
+        column_default: None,
+        ..Default::default()
+    });
+    existing
+}
+
+#[cfg(feature = "duckdb-sidecar")]
+#[test]
+fn duckdb_column_rename_generates_quoted_sql() {
+    let mut renamed = existing_duckdb_column("old_name");
+    renamed.name = "new_name".to_string();
+
+    let result =
+        build_table_structure_change_sql(structure_change_options(DatabaseType::DuckDb, None, "events", vec![renamed]));
+
+    assert!(result.warnings.is_empty(), "{:?}", result.warnings);
+    assert_eq!(result.statements, vec![r#"ALTER TABLE "events" RENAME COLUMN "old_name" TO "new_name";"#]);
+}
+
+#[cfg(feature = "duckdb-sidecar")]
+#[test]
+fn duckdb_column_rename_quotes_special_identifiers() {
+    let mut renamed = existing_duckdb_column("old \"code\"");
+    renamed.name = "select value".to_string();
+
+    let result = build_table_structure_change_sql(structure_change_options(
+        DatabaseType::DuckDb,
+        None,
+        "event log",
+        vec![renamed],
+    ));
+
+    assert!(result.warnings.is_empty(), "{:?}", result.warnings);
+    assert_eq!(result.statements, vec![r#"ALTER TABLE "event log" RENAME COLUMN "old ""code""" TO "select value";"#]);
+}
+
+#[cfg(feature = "duckdb-sidecar")]
+#[test]
+fn duckdb_column_rename_ignores_unchanged_columns() {
+    let unchanged = existing_duckdb_column("event_id");
+
+    let result = build_table_structure_change_sql(structure_change_options(
+        DatabaseType::DuckDb,
+        None,
+        "events",
+        vec![unchanged],
+    ));
+
+    assert!(result.statements.is_empty());
+    assert!(result.warnings.is_empty());
+}
+
+#[cfg(feature = "duckdb-sidecar")]
+#[test]
+fn duckdb_column_rename_with_unsupported_attribute_change_fails_closed() {
+    let mut changed = existing_duckdb_column("event_id");
+    changed.name = "renamed_id".to_string();
+    changed.data_type = "BIGINT".to_string();
+    changed.is_nullable = false;
+    changed.default_value = "42".to_string();
+
+    let result =
+        build_table_structure_change_sql(structure_change_options(DatabaseType::DuckDb, None, "events", vec![changed]));
+
+    assert!(result.statements.is_empty());
+    assert_eq!(result.warnings, vec!["Editing existing columns is not supported for duckdb yet."]);
+}
+
 #[test]
 fn builds_clickhouse_nullable_comment_and_reorder_statements() {
     let mut source = column("source");