test: add generated-column fixtures and fix AT_SetExpression/AT_DropExpression deparsing

__fixtures__/generated/generated.json

@@ -21372,6 +21372,14 @@
   "misc/indexes-11.sql": "DROP INDEX CONCURRENTLY IF EXISTS my_index CASCADE",
   "misc/indexes-12.sql": "CREATE UNIQUE INDEX new_unique_idx ON new_example(a, b) INCLUDE (c)",
   "misc/indexes-13.sql": "CREATE INDEX CONCURRENTLY idx_with_operator ON boom.merkle_tree USING GIN ( name gin_trgm_ops ( param1 = 32, param2 = true) )",
+  "misc/generated-columns-1.sql": "CREATE TABLE generated_misc_test (\n  a INT,\n  b INT,\n  c INT GENERATED ALWAYS AS (a + b) STORED\n)",
+  "misc/generated-columns-2.sql": "CREATE TABLE generated_func_test (\n  name TEXT,\n  name_upper TEXT GENERATED ALWAYS AS (upper(name)) STORED\n)",
+  "misc/generated-columns-3.sql": "CREATE TABLE generated_numeric_test (\n  quantity INT,\n  unit_price NUMERIC(10, 2),\n  total_price NUMERIC(10, 2) GENERATED ALWAYS AS (quantity * unit_price) STORED NOT NULL UNIQUE\n)",
+  "misc/generated-columns-4.sql": "CREATE TABLE generated_case_test (\n  flag BOOLEAN,\n  result INT GENERATED ALWAYS AS (CASE WHEN flag THEN 1 ELSE 0 END) STORED\n)",
+  "misc/generated-columns-5.sql": "ALTER TABLE generated_misc_test\nADD COLUMN d INT GENERATED ALWAYS AS (a + b + c) STORED",
+  "misc/generated-columns-6.sql": "ALTER TABLE generated_misc_test\nALTER COLUMN c SET EXPRESSION AS (a - b)",
+  "misc/generated-columns-7.sql": "ALTER TABLE generated_misc_test\nALTER COLUMN c DROP EXPRESSION",
+  "misc/generated-columns-8.sql": "ALTER TABLE generated_misc_test\nALTER COLUMN c DROP EXPRESSION IF EXISTS",
   "misc/extract-1.sql": "SELECT EXTRACT(EPOCH FROM now())",
   "misc/extract-2.sql": "SELECT EXTRACT(EPOCH FROM DATE '1970-01-01')",
   "misc/extract-3.sql": "SELECT EXTRACT(EPOCH FROM TIMESTAMP '1970-01-01')",

__fixtures__/kitchen-sink/misc/generated-columns.sql

@@ -0,0 +1,41 @@
+-- 1. CREATE TABLE with a generated column (arithmetic expression)
+CREATE TABLE generated_misc_test (
+  a INT,
+  b INT,
+  c INT GENERATED ALWAYS AS (a + b) STORED
+);
+
+-- 2. Generated column with a function call
+CREATE TABLE generated_func_test (
+  name TEXT,
+  name_upper TEXT GENERATED ALWAYS AS (upper(name)) STORED
+);
+
+-- 3. Generated column with type modifier and NOT NULL/UNIQUE
+CREATE TABLE generated_numeric_test (
+  quantity INT,
+  unit_price NUMERIC(10, 2),
+  total_price NUMERIC(10, 2) GENERATED ALWAYS AS (quantity * unit_price) STORED NOT NULL UNIQUE
+);
+
+-- 4. Generated column with a CASE expression
+CREATE TABLE generated_case_test (
+  flag BOOLEAN,
+  result INT GENERATED ALWAYS AS (CASE WHEN flag THEN 1 ELSE 0 END) STORED
+);
+
+-- 5. ALTER TABLE ADD COLUMN generated
+ALTER TABLE generated_misc_test
+ADD COLUMN d INT GENERATED ALWAYS AS (a + b + c) STORED;
+
+-- 6. ALTER TABLE SET EXPRESSION (new expression for an existing generated column)
+ALTER TABLE generated_misc_test
+ALTER COLUMN c SET EXPRESSION AS (a - b);
+
+-- 7. ALTER TABLE DROP EXPRESSION
+ALTER TABLE generated_misc_test
+ALTER COLUMN c DROP EXPRESSION;
+
+-- 8. ALTER TABLE DROP EXPRESSION IF EXISTS
+ALTER TABLE generated_misc_test
+ALTER COLUMN c DROP EXPRESSION IF EXISTS;

packages/deparser/__tests__/kitchen-sink/misc-generated-columns.test.ts

@@ -0,0 +1,16 @@
+
+import { FixtureTestUtils } from '../../test-utils';
+const fixtures = new FixtureTestUtils();
+
+it('misc-generated-columns', async () => {
+  await fixtures.runFixtureTests([
+  "misc/generated-columns-1.sql",
+  "misc/generated-columns-2.sql",
+  "misc/generated-columns-3.sql",
+  "misc/generated-columns-4.sql",
+  "misc/generated-columns-5.sql",
+  "misc/generated-columns-6.sql",
+  "misc/generated-columns-7.sql",
+  "misc/generated-columns-8.sql"
+]);
+});

packages/deparser/src/deparser.ts

@@ -5339,7 +5339,8 @@ export class Deparser implements DeparserVisitor {
           }
           output.push('SET EXPRESSION');
           if (node.def) {
-            output.push(this.visit(node.def, context));
+            output.push('AS');
+            output.push(context.parens(this.visit(node.def, context)));
           }
           break;
         case 'AT_DropExpression':
@@ -5348,6 +5349,9 @@ export class Deparser implements DeparserVisitor {
             output.push(QuoteUtils.quoteIdentifier(node.name));
           }
           output.push('DROP EXPRESSION');
+          if (node.missing_ok) {
+            output.push('IF EXISTS');
+          }
           break;
         case 'AT_CheckNotNull':
           output.push('ALTER COLUMN');