Feat: Support check constraint

dbml-homepage/docs/docs.md

@@ -17,6 +17,8 @@ outlines the full syntax documentations of DBML.
 - [Column Definition](#column-definition)
   - [Column Settings](#column-settings)
   - [Default Value](#default-value)
+- [Constraint Definition](#constraint-definition)
+  - [Constraint Settings](#constraint-settings)
 - [Index Definition](#index-definition)
   - [Index Settings](#index-settings)
 - [Relationships & Foreign Key Definitions](#relationships--foreign-key-definitions)
@@ -177,6 +179,7 @@ The list of column settings you can use:
 - `unique`: mark the column unique
 - `default: some_value`: set a default value of the column, please refer to the 'Default Value' section below
 - `increment`: mark the column as auto-increment
+- ``constraint: `check expression` ``: add a check expression to this column. Multiple constraints can be defined on a column. For constraints involving multiple columns, refer to the 'Constraints' section
 
 **Note:** You can use a workaround for un-supported settings by adding the setting name into the column type name, such as `id "bigint unsigned" [pk]`
 
@@ -202,6 +205,25 @@ Table users {
   rating integer [default: 10]
 }
 ```
+## Constraint Definition
+
+Constraints allow users to specify custom checks on one or many columns. These checks can be used to enforce constraints on the possible values of one or many columns, which are otherwise impossible to express.
+
+```text
+Table users {
+  id integer
+  wealth integer
+  debt integer
+
+  constraints {
+    `debt + wealth >= 0` [name: 'chk_positive_money']
+  }
+}
+```
+
+### Constraint Settings
+
+- `name`: name of constraint
 
 ## Index Definition
 

packages/dbml-cli/__test__/sql2dbml/multiple_schema_mssql/expect-out-files/multiple_schema.out.dbml

@@ -1,34 +1,10 @@
-Enum "users_pjs_enum" {
-  "created2"
-  "running2"
-  "done2"
-  "failure2"
-}
-
-Enum "users_pjs2_enum" {
-  "created2"
-  "running2"
-  "done2"
-  "failure2"
-}
-
-Enum "users_pg_enum" {
-  "male"
-  "female"
-}
-
-Enum "users_pg2_enum" {
-  "male2"
-  "female2"
-}
-
 Table "users" {
   "id" int [pk]
   "name" nvarchar(255)
-  "pjs" users_pjs_enum [not null]
-  "pjs2" users_pjs2_enum [not null]
-  "pg" users_pg_enum [not null]
-  "pg2" users_pg2_enum [not null]
+  "pjs" nvarchar(255) [not null, constraint: `[pjs] IN ('created2', 'running2', 'done2', 'failure2')`]
+  "pjs2" nvarchar(255) [not null, constraint: `[pjs2] IN ('created2', 'running2', 'done2', 'failure2')`]
+  "pg" nvarchar(255) [not null, constraint: `[pg] IN ('male', 'female')`]
+  "pg2" nvarchar(255) [not null, constraint: `[pg2] IN ('male2', 'female2')`]
 }
 
 Table "products" {
@@ -48,37 +24,13 @@ Ref:"ecommerce"."users"."id" < "schemaA"."products"."name"
 
 Ref:"users"."id" < "schemaA"."locations"."name"
 
-Enum "ecommerce"."users_ejs_enum" {
-  "created2"
-  "running2"
-  "done2"
-  "failure2"
-}
-
-Enum "ecommerce"."users_ejs2_enum" {
-  "created2"
-  "running2"
-  "done2"
-  "failure2"
-}
-
-Enum "ecommerce"."users_eg_enum" {
-  "male"
-  "female"
-}
-
-Enum "ecommerce"."users_eg2_enum" {
-  "male2"
-  "female2"
-}
-
 Table "ecommerce"."users" {
   "id" int [pk]
   "name" nvarchar(255)
-  "ejs" ecommerce.users_ejs_enum [not null]
-  "ejs2" ecommerce.users_ejs2_enum [not null]
-  "eg" ecommerce.users_eg_enum [not null]
-  "eg2" ecommerce.users_eg2_enum [not null]
+  "ejs" nvarchar(255) [not null, constraint: `[ejs] IN ('created2', 'running2', 'done2', 'failure2')`]
+  "ejs2" nvarchar(255) [not null, constraint: `[ejs2] IN ('created2', 'running2', 'done2', 'failure2')`]
+  "eg" nvarchar(255) [not null, constraint: `[eg] IN ('male', 'female')`]
+  "eg2" nvarchar(255) [not null, constraint: `[eg2] IN ('male2', 'female2')`]
 
   Indexes {
     (name, ejs) [name: "idx_1"]

packages/dbml-core/__tests__/importer/mssql_importer/input/constraints.in.sql

@@ -0,0 +1,259 @@
+-- Comprehensive test for CHECK constraints in MSSQL
+-- Tests various edge cases including brackets, quotes, complex expressions
+
+-- Test 1: Column-level constraints with simple conditions
+CREATE TABLE products (
+  id INT PRIMARY KEY,
+  price DECIMAL(10,2) CHECK (price > 0),
+  quantity INT CHECK (quantity >= 0),
+  discount DECIMAL(5,2) CHECK (discount >= 0 AND discount <= 100)
+);
+
+-- Test 2: Table-level named constraints
+CREATE TABLE employees (
+  emp_id INT PRIMARY KEY,
+  age INT,
+  salary DECIMAL(10,2),
+  CONSTRAINT chk_age CHECK (age >= 18 AND age <= 65),
+  CONSTRAINT chk_salary CHECK (salary > 0)
+);
+
+-- Test 3: Constraints with bracket-quoted identifiers (MSSQL style)
+CREATE TABLE [special_table] (
+  [id] INT PRIMARY KEY,
+  [price] DECIMAL CHECK ([price] > 0),
+  [status] VARCHAR(20) CHECK ([status] IN ('active', 'inactive'))
+);
+
+-- Test 4: Constraints with complex expressions
+CREATE TABLE [transactions] (
+  txn_id INT PRIMARY KEY,
+  amount DECIMAL(10,2),
+  fee DECIMAL(10,2),
+  total DECIMAL(10,2),
+  CHECK (total = amount + fee),
+  CHECK (amount > 0 OR fee > 0)
+);
+
+-- Test 5: Constraints with string comparisons and LIKE
+CREATE TABLE contacts (
+  contact_id INT PRIMARY KEY,
+  email VARCHAR(100) CHECK (email LIKE '%@%'),
+  phone VARCHAR(20) CHECK (phone LIKE '[0-9][0-9][0-9]-[0-9][0-9][0-9]-[0-9][0-9][0-9][0-9]')
+);
+
+-- Test 6: Constraints with IN operator and multiple values
+CREATE TABLE orders (
+  order_id INT PRIMARY KEY,
+  status VARCHAR(20) CHECK (status IN ('pending', 'processing', 'shipped', 'delivered', 'cancelled')),
+  priority INT CHECK (priority IN (1, 2, 3, 4, 5))
+);
+
+-- Test 7: Constraints with NOT IN
+CREATE TABLE users (
+  user_id INT PRIMARY KEY,
+  role VARCHAR(20) CHECK (role NOT IN ('banned', 'deleted', 'suspended'))
+);
+
+-- Test 8: Constraints with nested parentheses
+CREATE TABLE ranges (
+  range_id INT PRIMARY KEY,
+  min_val INT,
+  max_val INT,
+  CHECK ((min_val >= 0) AND (max_val <= 100) AND (min_val < max_val))
+);
+
+-- Test 9: Constraints with CASE expressions
+CREATE TABLE inventory (
+  item_id INT PRIMARY KEY,
+  stock INT,
+  status VARCHAR(20),
+  CHECK (
+    CASE
+      WHEN status = 'active' THEN stock
+      WHEN status = 'discontinued' THEN 0
+      ELSE 1
+    END >= 0
+  )
+);
+
+-- Test 10: Multiple constraints on same table (mixed column and table level)
+CREATE TABLE accounts (
+  account_id INT PRIMARY KEY,
+  balance DECIMAL(15,2) CHECK (balance >= 0),
+  overdraft_limit DECIMAL(15,2) CHECK (overdraft_limit >= 0),
+  CONSTRAINT chk_balance_overdraft CHECK (balance + overdraft_limit >= 0)
+);
+
+-- Test 11: ALTER TABLE ADD CONSTRAINT (named)
+CREATE TABLE shipments (
+  shipment_id INT PRIMARY KEY,
+  weight DECIMAL(10,2),
+  cost DECIMAL(10,2)
+);
+
+ALTER TABLE shipments ADD CONSTRAINT chk_weight CHECK (weight > 0);
+ALTER TABLE shipments ADD CONSTRAINT chk_cost CHECK (cost >= 0);
+
+-- Test 12: ALTER TABLE ADD CONSTRAINT (unnamed - MSSQL auto-generates name)
+CREATE TABLE payments (
+  payment_id INT PRIMARY KEY,
+  amount DECIMAL(10,2)
+);
+
+ALTER TABLE payments ADD CHECK (amount > 0);
+
+-- Test 13: Constraints with mathematical expressions
+CREATE TABLE pricing (
+  price_id INT PRIMARY KEY,
+  base_price DECIMAL(10,2),
+  discount_pct DECIMAL(5,2),
+  final_price DECIMAL(10,2),
+  CHECK (final_price = base_price * (1 - discount_pct / 100))
+);
+
+-- Test 14: Constraints with COALESCE and NULL handling
+CREATE TABLE settings (
+  setting_id INT PRIMARY KEY,
+  value VARCHAR(100),
+  default_value VARCHAR(100),
+  CHECK (COALESCE(value, default_value) IS NOT NULL)
+);
+
+-- Test 15: Constraints with date/time operations
+CREATE TABLE bookings (
+  booking_id INT PRIMARY KEY,
+  check_in DATE,
+  check_out DATE,
+  CHECK (check_out > check_in),
+  CHECK (check_in >= GETDATE())
+);
+
+-- Test 16: Constraints with string functions
+CREATE TABLE documents (
+  doc_id INT PRIMARY KEY,
+  title VARCHAR(200),
+  content VARCHAR(MAX),
+  CHECK (LEN(title) > 0),
+  CHECK (LEN(content) >= 10)
+);
+
+-- Test 17: Multiple CHECK constraints with OR conditions
+CREATE TABLE events (
+  event_id INT PRIMARY KEY,
+  status VARCHAR(20),
+  cancelled BIT,
+  CHECK (status = 'active' OR status = 'completed' OR cancelled = 1)
+);
+
+-- Test 18: Constraints with BETWEEN
+CREATE TABLE grades (
+  grade_id INT PRIMARY KEY,
+  score INT,
+  CHECK (score BETWEEN 0 AND 100)
+);
+
+-- Test 19: Named constraints with brackets in names
+CREATE TABLE products_special (
+  product_id INT PRIMARY KEY,
+  code VARCHAR(50),
+  CONSTRAINT [chk_code_format] CHECK (code LIKE '[A-Z][A-Z][A-Z]-[0-9][0-9][0-9][0-9]')
+);
+
+-- Test 20: Constraint with bit column
+CREATE TABLE features (
+  feature_id INT PRIMARY KEY,
+  is_enabled BIT,
+  is_premium BIT,
+  CHECK (is_enabled = 1 OR is_premium = 0)
+);
+
+-- Test 21: Constraints with ISNULL (MSSQL specific)
+CREATE TABLE configs (
+  config_id INT PRIMARY KEY,
+  value1 INT,
+  value2 INT,
+  CHECK (ISNULL(value1, 0) + ISNULL(value2, 0) > 0)
+);
+
+-- Test 22: Multiple ALTER TABLE statements on same table
+CREATE TABLE audit_log (
+  log_id INT PRIMARY KEY,
+  severity INT,
+  message VARCHAR(MAX)
+);
+
+ALTER TABLE audit_log ADD CONSTRAINT chk_severity_range CHECK (severity BETWEEN 1 AND 5);
+ALTER TABLE audit_log ADD CONSTRAINT chk_message_length CHECK (LEN(message) > 0);
+ALTER TABLE audit_log ADD CHECK (severity > 0);
+
+-- Test 23: Constraints with comparison operators
+CREATE TABLE limits (
+  limit_id INT PRIMARY KEY,
+  min_value INT,
+  max_value INT,
+  CHECK (max_value > min_value),
+  CHECK (min_value >= 0),
+  CHECK (max_value <= 1000)
+);
+
+-- Test 24: Constraints with != and <> operators
+CREATE TABLE statuses (
+  status_id INT PRIMARY KEY,
+  current_status VARCHAR(20),
+  previous_status VARCHAR(20),
+  CHECK (current_status != previous_status),
+  CHECK (current_status <> '')
+);
+
+-- Test 25: Table with brackets in names and constraint expressions
+CREATE TABLE [order_items] (
+  [order_item_id] INT PRIMARY KEY,
+  [order_id] INT,
+  [quantity] INT,
+  [unit_price] DECIMAL(10,2),
+  CHECK ([quantity] > 0),
+  CONSTRAINT [chk_price_positive] CHECK ([unit_price] > 0)
+);
+
+-- Test 26: Constraint with modulo operator
+CREATE TABLE sequences (
+  seq_id INT PRIMARY KEY,
+  value INT,
+  CHECK (value % 2 = 0)
+);
+
+-- Test 27: Constraint with ABS function
+CREATE TABLE temperatures (
+  temp_id INT PRIMARY KEY,
+  celsius DECIMAL(5,2),
+  CHECK (ABS(celsius) < 100)
+);
+
+-- Test 28: Constraint with CHARINDEX
+CREATE TABLE emails (
+  email_id INT PRIMARY KEY,
+  email_address VARCHAR(100),
+  CHECK (CHARINDEX('@', email_address) > 0)
+);
+
+-- Test 29: Constraint with UPPER/LOWER
+CREATE TABLE codes (
+  code_id INT PRIMARY KEY,
+  code VARCHAR(50),
+  CHECK (code = UPPER(code))
+);
+
+-- Test 30: Complex multi-column constraint
+CREATE TABLE order_discounts (
+  discount_id INT PRIMARY KEY,
+  order_total DECIMAL(10,2),
+  discount_pct DECIMAL(5,2),
+  discount_amt DECIMAL(10,2),
+  final_total DECIMAL(10,2),
+  CONSTRAINT chk_discount_calculation CHECK (
+    (discount_amt = order_total * discount_pct / 100) AND
+    (final_total = order_total - discount_amt) AND
+    (final_total >= 0)
+  )
+);