SQL to ERD guide

-- Define custom types
CREATE TYPE status_enum AS ENUM (
  'active', 'inactive', 'suspended'
);

-- Create tables with constraints
CREATE TABLE departments (
  id SERIAL PRIMARY KEY,
  name VARCHAR(100) NOT NULL UNIQUE
);

CREATE TABLE employees (
  id SERIAL PRIMARY KEY,
  name VARCHAR(100) NOT NULL,
  email TEXT UNIQUE NOT NULL,
  status status_enum DEFAULT 'active',
  department_id INTEGER,
  salary NUMERIC(10, 2) DEFAULT 0
);

-- Add constraints via ALTER TABLE
ALTER TABLE employees
  ADD CONSTRAINT fk_dept
  FOREIGN KEY (department_id)
  REFERENCES departments(id);

-- Add sample data after schema DDL
INSERT INTO departments (id, name) VALUES
  (1, 'Engineering'),
  (2, 'Design');

INSERT INTO employees (id, name, email, status, department_id, salary) VALUES
  (1, 'Alice', '[email protected]', 'active', 1, 1500.00),
  (2, 'Bob', '[email protected]', 'inactive', 2, 1200.00);

UPDATE employees
  SET status = 'active'
  WHERE id = 2;

SELECT e.name, d.name AS department, e.salary
FROM employees e
JOIN departments d ON d.id = e.department_id
WHERE e.status = 'active'
ORDER BY e.salary DESC;

-- Schema statements
CREATE TYPE type_name AS ENUM (...);
CREATE TYPE type_name AS (...);
CREATE TABLE table_name (...);
CREATE OR REPLACE TABLE table_name (...);
CREATE VIEW view_name AS SELECT ...;
CREATE OR REPLACE VIEW view_name AS SELECT ...;
CREATE OR ALTER VIEW view_name AS SELECT ...;
ALTER TABLE table_name ADD ...;
ALTER TABLE table_name DROP COLUMN column_name;
ALTER TABLE table_name RENAME COLUMN old_name TO new_name;
CREATE INDEX index_name ON table_name (column_name);
DROP INDEX index_name;
TRUNCATE TABLE table_name;
DROP TABLE [IF EXISTS] table_name;
DROP VIEW [IF EXISTS] view_name;
DROP TYPE [IF EXISTS] type_name;

-- Data statements
INSERT INTO table_name [(col1, col2, ...)] VALUES (...), (...);
UPDATE table_name SET col1 = value WHERE condition;
DELETE FROM table_name WHERE condition;

WITH dept_totals AS (
  SELECT department_id, COUNT(*) AS employee_count, SUM(salary) AS payroll
  FROM employees
  GROUP BY department_id
)
SELECT d.name,
       dt.employee_count,
       dt.payroll
FROM dept_totals dt
JOIN departments d ON d.id = dt.department_id
WHERE dt.employee_count >= 1
ORDER BY dt.payroll DESC
LIMIT 10;

// Every entry the editor receives has this shape:
{
  message:  "Column 'a' missing data type",
  severity: "error" | "warning",
  position: { line: 1, column: 17, index: 16 },
  token?:   { type, value, raw }   // present for parser-side errors
}

// Each log entry is:
{
  type:      "success" | "warning" | "error",
  message:   "Inserted 3 row(s) into \"users\"",
  timestamp: 1734567890123  // ms since epoch, monotonic
}

-- Examples ────────────────────────────────────────────────
-- success
CREATE TABLE users (id INT PRIMARY KEY);
-- → success: Table "users" created with 1 columns

-- warning (no WHERE clause)
UPDATE users SET id = 99;
-- → warning: UPDATE "users": no WHERE clause — all 2 row(s) will be affected
-- → success: Updated 2 row(s) in "users"

-- error (unknown table)
INSERT INTO ghost VALUES (1);
-- → error: INSERT INTO "ghost": table does not exist

error    : INSERT INTO "x": unknown column(s): foo
warning  : INSERT INTO "x" row 3: expected 4 values but got 3
warning  : UPDATE "x": setting NOT NULL column "name" to NULL
warning  : DELETE FROM "x": no WHERE clause — all 1200 row(s) will be removed
error    : DROP: table "ghost" does not exist
warning  : ALTER "x": column "old_col" does not exist
warning  : Relation dropped: foreign key 'posts.user_id' references column
           'users.no_such' which does not exist on table 'users'.
warning  : Relation dropped: foreign key 'events.email' references 'users.email',
           but the target is only partial-unique, not globally unique.

CREATE TYPE type_name AS (
  field1 data_type1,
  field2 data_type2,
  ...
);

CREATE TYPE address_type AS (
  street VARCHAR(100),
  city TEXT,
  postal_code INTEGER
);

CREATE TYPE coordinates AS (
  latitude DECIMAL(10, 8),
  longitude DECIMAL(11, 8)
);

CREATE TYPE enum_name AS ENUM (
  'value1',
  'value2',
  ...
);

CREATE TYPE status_enum AS ENUM (
  'pending',
  'active',
  'completed',
  'cancelled'
);

CREATE TYPE priority_level AS ENUM (
  'low', 'medium', 'high', 'critical'
);

CREATE TYPE s1.status AS ENUM ('draft', 'active');
CREATE TYPE s2.status AS ENUM ('queued', 'done');

CREATE TABLE s1.items (
  id    INT PRIMARY KEY,
  state s1.status
);

CREATE TABLE s2.items (
  id    INT PRIMARY KEY,
  state s2.status
);

CREATE TABLE table_name (
  column_name data_type [constraints],
  ...
  -- table-level constraints (optional)
);

-- Also supports:
CREATE TABLE IF NOT EXISTS table_name ( ... );
CREATE TABLE schema_name.table_name ( ... );

CREATE TABLE users (
  id INTEGER PRIMARY KEY,
  username VARCHAR(50) UNIQUE NOT NULL,
  email TEXT NOT NULL CHECK (email LIKE '%@%'),
  status VARCHAR(20) DEFAULT 'active',
  created_at TIMESTAMP DEFAULT now(),
  department_id INTEGER REFERENCES departments(id)
);

CREATE TABLE products (
  id SERIAL PRIMARY KEY,
  price NUMERIC(10, 2),
  quantity INTEGER,

  -- PostgreSQL / MySQL: parenthesized expression
  total NUMERIC GENERATED ALWAYS AS (price * quantity) STORED,

  -- MySQL VIRTUAL column
  discount NUMERIC GENERATED ALWAYS AS (price * 0.1) VIRTUAL
);

CREATE TABLE tasks (
  id INTEGER PRIMARY KEY,
  status ENUM('todo', 'doing', 'done'),
  priority ENUM('low', 'medium', 'high')
);

-- Syntax:
[CONSTRAINT name] PRIMARY KEY (col1, col2, ...)

[CONSTRAINT name] FOREIGN KEY (col1, col2, ...)
  REFERENCES ref_table(ref_col1, ref_col2, ...)
  [MATCH FULL|PARTIAL|SIMPLE]
  [ON DELETE CASCADE|RESTRICT|SET NULL|SET DEFAULT|NO ACTION]
  [ON UPDATE CASCADE|RESTRICT|SET NULL|SET DEFAULT|NO ACTION]
  [DEFERRABLE|NOT DEFERRABLE] [INITIALLY DEFERRED|IMMEDIATE]

[CONSTRAINT name] UNIQUE (col1, col2, ...)

[CONSTRAINT name] CHECK (expression)

CREATE TABLE order_items (
  order_id INTEGER,
  product_id INTEGER,
  quantity INTEGER CHECK (quantity > 0),
  unit_price NUMERIC(10, 2),

  CONSTRAINT pk_order_items
    PRIMARY KEY (order_id, product_id),
  CONSTRAINT fk_order
    FOREIGN KEY (order_id) REFERENCES orders(id),
  CONSTRAINT fk_product
    FOREIGN KEY (product_id) REFERENCES products(id),
  CONSTRAINT uq_order_product
    UNIQUE (order_id, product_id),
  CONSTRAINT chk_price
    CHECK (unit_price >= 0)
);

CREATE TABLE feature_flags (
  id        BIGSERIAL PRIMARY KEY,
  org_id    BIGINT NOT NULL,
  key       VARCHAR(128) NOT NULL,   -- 'key' as column name → OK
  index     INT,                     -- 'index' as column name → OK
  value     TEXT,                    -- 'value' as column name → OK
  enabled   BOOLEAN NOT NULL DEFAULT FALSE,
  UNIQUE (org_id, key)
);

-- The MySQL "KEY ... (cols)" index form is still recognized correctly
CREATE TABLE posts (
  id   INT PRIMARY KEY,
  body TEXT,
  KEY idx_body (body),                 -- treated as index, adds IDX badge
  FULLTEXT KEY ft_body (body)          -- treated as fulltext index badge
);

-- Rowid alias; auto assigns a value when omitted
CREATE TABLE users (
  id INTEGER PRIMARY KEY,
  email TEXT NOT NULL UNIQUE
);

-- AUTOINCREMENT prevents rowid reuse after DELETE
CREATE TABLE events (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  name TEXT NOT NULL
);

-- Invalid for SQLite AUTOINCREMENT:
-- 1. BIGINT PRIMARY KEY AUTOINCREMENT
-- 2. INT PRIMARY KEY AUTOINCREMENT
-- 3. AUTOINCREMENT on a composite primary key

-- Classic SERIAL family
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  big_id BIGSERIAL,
  small_id SMALLSERIAL
);

-- Modern SQL-standard identity columns
CREATE TABLE events (
  id BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  name TEXT
);

CREATE TABLE invoices (
  id BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY
);

CREATE TABLE users (
  id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
  email VARCHAR(255) NOT NULL UNIQUE
) ENGINE=InnoDB;

-- IDENTITY(seed, increment)
CREATE TABLE [dbo].[Customers] (
  [CustomerID] BIGINT IDENTITY(1,1) NOT NULL CONSTRAINT pk_customer PRIMARY KEY,
  [Email] NVARCHAR(255) NOT NULL
);

-- Bare IDENTITY (defaults to (1,1))
CREATE TABLE [dbo].[Orders] (
  [OrderID] INT IDENTITY NOT NULL PRIMARY KEY
);

CREATE TABLE products (
  id SERIAL PRIMARY KEY,
  price NUMERIC(10,2),
  qty INTEGER,
  total NUMERIC GENERATED ALWAYS AS (price * qty) STORED,
  discount NUMERIC GENERATED ALWAYS AS (price * 0.1) VIRTUAL
);

-- Complex expressions, including CASE
CREATE TABLE orders (
  id BIGSERIAL PRIMARY KEY,
  qty INT,
  flag INT GENERATED ALWAYS AS (CASE WHEN qty > 100 THEN 1 ELSE 0 END) STORED
);

CREATE TABLE [dbo].[Customers] (
  [CustomerID] BIGINT IDENTITY(1,1) NOT NULL CONSTRAINT pk_c PRIMARY KEY,
  [FirstName] NVARCHAR(50) NOT NULL,
  [LastName]  NVARCHAR(50) NOT NULL,

  -- Parenthesized form
  [FullName] AS ([FirstName] + ' ' + [LastName]) PERSISTED,

  -- Bare form (no parens) — also accepted
  [Initials] AS LEFT([FirstName], 1) + LEFT([LastName], 1)
);

CREATE TABLE [dbo].[Loans] (
  [LoanID] BIGINT IDENTITY(1,1) NOT NULL PRIMARY KEY,
  [StartDate] DATE NOT NULL,
  [TermMonths] INT NOT NULL,

  -- Function call in a bare AS expression
  [MaturityDate] AS DATEADD(MONTH, [TermMonths], [StartDate]) PERSISTED,

  -- CASE expression in a bare AS
  [SignedAmount] AS CASE WHEN [TermMonths] > 12 THEN 1 ELSE 0 END
);

ALTER TABLE table_name
  ADD [CONSTRAINT name] FOREIGN KEY (cols...)
    REFERENCES ref_table[(ref_cols...)]
    [ON DELETE action] [ON UPDATE action]
    [DEFERRABLE|NOT DEFERRABLE] [INITIALLY DEFERRED|IMMEDIATE];

ALTER TABLE orders
  ADD CONSTRAINT fk_orders_customer
  FOREIGN KEY (customer_id)
  REFERENCES customers(id)
  ON DELETE CASCADE;

ALTER TABLE table_name
  ADD [CONSTRAINT name] PRIMARY KEY (cols...);

ALTER TABLE products
  ADD CONSTRAINT pk_products
  PRIMARY KEY (product_id);

ALTER TABLE table_name
  ADD [CONSTRAINT name] UNIQUE (cols...);

ALTER TABLE users
  ADD CONSTRAINT uq_users_email
  UNIQUE (email);

ALTER TABLE table_name
  ADD [CONSTRAINT name] CHECK (expression);

ALTER TABLE employees
  ADD CONSTRAINT chk_salary
  CHECK (salary >= 0);

CREATE TYPE app.ticket_status AS ENUM ('new', 'open', 'closed');

CREATE TABLE app.accounts (
  tenant_id  INT NOT NULL,
  account_no TEXT NOT NULL,
  status     app.ticket_status NOT NULL DEFAULT 'new',
  PRIMARY KEY (tenant_id, account_no)
);

CREATE TABLE app.contacts (
  tenant_id   INT NOT NULL,
  account_no  TEXT NOT NULL,
  owner_email TEXT,
  CONSTRAINT fk_contacts_account
    FOREIGN KEY (tenant_id, account_no)
    REFERENCES app.accounts
    ON DELETE CASCADE
    DEFERRABLE INITIALLY DEFERRED
);

ALTER TABLE app.contacts ADD COLUMN audit_state TEXT;
ALTER TABLE app.contacts ALTER COLUMN owner_email TYPE VARCHAR(320);
ALTER TABLE app.contacts ALTER COLUMN owner_email SET NOT NULL;
ALTER TABLE app.contacts RENAME COLUMN owner_email TO contact_email;
ALTER TABLE app.contacts DROP COLUMN audit_state;

CREATE UNIQUE INDEX ux_contacts_email
  ON app.contacts (contact_email);

CREATE TABLE `customers` (
  `id` BIGINT AUTO_INCREMENT PRIMARY KEY,
  `email` VARCHAR(320) NOT NULL,
  UNIQUE INDEX `ux_customers_email` (`email`)
) ENGINE=InnoDB;

CREATE TABLE `orders` (
  `id` BIGINT AUTO_INCREMENT PRIMARY KEY,
  `customer_email` VARCHAR(320),
  `status` ENUM('new','paid') NOT NULL DEFAULT 'new',
  `old_note` VARCHAR(50),
  CONSTRAINT `fk_orders_customer`
    FOREIGN KEY (`customer_email`)
    REFERENCES `customers`(`email`)
    ON DELETE SET NULL
) ENGINE=InnoDB;

ALTER TABLE `orders`
  CHANGE COLUMN `old_note` `note` VARCHAR(255) NOT NULL;
ALTER TABLE `orders`
  MODIFY COLUMN `status` ENUM('new','paid') NOT NULL DEFAULT 'paid';

CREATE TABLE [dbo].[Customers] (
  [CustomerID] INT IDENTITY(1,1) NOT NULL,
  [Email] NVARCHAR(320) NOT NULL,
  CONSTRAINT [PK_Customers] PRIMARY KEY CLUSTERED ([CustomerID]),
  CONSTRAINT [UQ_Customers_Email] UNIQUE NONCLUSTERED ([Email])
);

CREATE TABLE [dbo].[Orders] (
  [OrderID] INT IDENTITY(1,1) NOT NULL,
  [CustomerEmail] NVARCHAR(320),
  [LegacyNote] NVARCHAR(50),
  CONSTRAINT [PK_Orders] PRIMARY KEY NONCLUSTERED ([OrderID]),
  CONSTRAINT [FK_Orders_Customers]
    FOREIGN KEY ([CustomerEmail])
    REFERENCES [dbo].[Customers]([Email])
    ON DELETE SET NULL
);

ALTER TABLE [dbo].[Orders]
  ALTER COLUMN [LegacyNote] NVARCHAR(255) NOT NULL;
ALTER TABLE [dbo].[Orders]
  ADD [CreatedAt] DATETIME2 NOT NULL DEFAULT '2026-01-01';

CREATE [UNIQUE] INDEX [IF NOT EXISTS] [name]
  ON [schema.]table (col1 [ASC|DESC] [NULLS FIRST|LAST], col2, ...)
  [INCLUDE (cols)]      -- PG / MSSQL: covering columns (no badge added)
  [WHERE predicate]     -- PG / MSSQL: partial / filtered index
  [USING method]        -- PG: btree, hash, gin, gist, brin
  [WITH (options)];     -- storage parameters

CREATE INDEX idx_orders_customer ON orders (customer_id);

CREATE INDEX idx_orders_customer_status
  ON orders (customer_id, status);

CREATE UNIQUE INDEX uq_shipments_tracking
  ON shipments (tracking_number);

CREATE UNIQUE INDEX ux_users_active_email
  ON users (email)
  WHERE deleted_at IS NULL;

CREATE TABLE posts (
  id INT PRIMARY KEY,
  slug VARCHAR(160) NOT NULL,
  body TEXT,
  UNIQUE INDEX ux_posts_slug (slug),
  KEY idx_posts_body (body),
  FULLTEXT KEY ft_body (body)
);

CREATE NONCLUSTERED INDEX idx_active_orders
  ON orders (customer_id)
  INCLUDE (total)
  WHERE status = 'active';

-- SQLite uses type affinities: INTEGER, TEXT, REAL, NUMERIC, BLOB
CREATE TABLE users (
  id       INTEGER PRIMARY KEY,         -- implicit rowid alias
  email    TEXT UNIQUE NOT NULL,
  name     TEXT NOT NULL,
  balance  REAL DEFAULT 0.0,
  metadata BLOB,
  created  TEXT DEFAULT (datetime('now'))
);

-- AUTOINCREMENT prevents rowid reuse after DELETE
CREATE TABLE events (
  id   INTEGER PRIMARY KEY AUTOINCREMENT,
  name TEXT NOT NULL,
  ts   TEXT DEFAULT CURRENT_TIMESTAMP
);

-- WITHOUT ROWID — clustered on the declared PRIMARY KEY
CREATE TABLE kv_store (
  key   TEXT PRIMARY KEY,
  value TEXT
) WITHOUT ROWID;

-- STRICT mode — enforces declared column types
CREATE TABLE audit_log (
  id      INTEGER PRIMARY KEY,
  action  TEXT NOT NULL,
  payload TEXT
) STRICT;

-- STRICT + WITHOUT ROWID combined
CREATE TABLE config (
  key   TEXT PRIMARY KEY,
  value TEXT NOT NULL
) STRICT, WITHOUT ROWID;

-- Foreign keys with ON DELETE / ON UPDATE actions
CREATE TABLE orders (
  id          INTEGER PRIMARY KEY,
  customer_id INTEGER NOT NULL
    REFERENCES users(id) ON DELETE CASCADE ON UPDATE SET NULL,
  total       REAL DEFAULT 0 CHECK (total >= 0)
);

-- IF NOT EXISTS works as expected
CREATE TABLE IF NOT EXISTS sessions (
  token   TEXT PRIMARY KEY,
  user_id INTEGER REFERENCES users(id),
  expires TEXT
);

CREATE TABLE authors (
  id    INTEGER PRIMARY KEY,
  email TEXT NOT NULL UNIQUE
) STRICT;

CREATE TABLE posts (
  author_id INTEGER NOT NULL
    REFERENCES authors(id) ON DELETE CASCADE ON UPDATE RESTRICT,
  post_id   TEXT NOT NULL,
  body      TEXT,
  PRIMARY KEY (author_id, post_id)
) STRICT, WITHOUT ROWID;

ALTER TABLE posts ADD COLUMN summary TEXT;
ALTER TABLE posts RENAME COLUMN summary TO excerpt;
ALTER TABLE authors RENAME TO writers;

-- Composite type + ENUM + array column types
CREATE TYPE address AS (street TEXT, city VARCHAR(100), zip VARCHAR(20));
CREATE TYPE org_plan AS ENUM ('free','starter','pro','enterprise');

CREATE TABLE organizations (
  id            BIGSERIAL PRIMARY KEY,
  -- Or: id BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY
  name          VARCHAR(255) NOT NULL,
  plan          org_plan NOT NULL DEFAULT 'free',

  -- PostgreSQL-specific types
  billing_addr  address,                          -- composite type
  data          JSONB DEFAULT '{}',               -- JSON binary
  tags          TEXT[],                           -- 1-D array
  matrix        INT[5],                           -- sized array
  uuid          UUID DEFAULT gen_random_uuid(),
  ip            INET,
  ts            TIMESTAMPTZ DEFAULT NOW(),

  -- Dollar-quoted defaults
  description   TEXT DEFAULT $Hello World$,

  -- Type casting in defaults
  seq_id        INTEGER DEFAULT nextval('org_seq'::regclass)
);

-- Schema-qualified table & type references both work
CREATE TABLE public.users (
  id INTEGER PRIMARY KEY,
  status public.org_plan          -- schema-qualified user-defined type
);

-- Empty body INHERITS (PG-only)
CREATE TABLE child () INHERITS (parent);

-- Backtick-quoted identifiers + ENGINE / CHARSET / COLLATE
CREATE TABLE `users` (
  `id` BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
  `name` VARCHAR(100) NOT NULL,

  -- Inline ENUM and SET (auto-registered as named types)
  `status` ENUM('active', 'inactive', 'suspended') NOT NULL DEFAULT 'active',
  `flags`  SET('verified','staff','beta','muted'),

  -- UNSIGNED / SIGNED modifiers + TINYINT(1)
  `age`     TINYINT UNSIGNED,
  `is_pro`  TINYINT(1) UNSIGNED DEFAULT 0,

  -- COMMENT on columns
  `email` VARCHAR(255) COMMENT 'User email address',

  -- Timestamps with ON UPDATE CURRENT_TIMESTAMP
  `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,

  -- MySQL-specific types
  `bio`         MEDIUMTEXT,
  `avatar`      LONGBLOB,
  `birth_year` YEAR(4),
  `location`    POINT,

  -- Inline indexes become ERD badges when they map to columns
  INDEX idx_name (`name`),
  FULLTEXT KEY ft_bio (`bio`),
  UNIQUE INDEX ux_name (`name`),
  UNIQUE KEY uk_email (`email`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- Bracket-quoted identifiers + IDENTITY + computed columns
CREATE TABLE [dbo].[Users] (
  [UserID]      BIGINT IDENTITY(1,1) NOT NULL CONSTRAINT pk_users PRIMARY KEY CLUSTERED,
  [FirstName]   NVARCHAR(50) NOT NULL,
  [LastName]    NVARCHAR(50) NOT NULL,

  -- Computed column (parenthesized form)
  [FullName]    AS ([FirstName] + ' ' + [LastName]) PERSISTED,

  -- Computed column (bare AS form — also supported)
  [Initials]    AS LEFT([FirstName],1) + LEFT([LastName],1),

  -- MSSQL-specific types
  [IsActive]    BIT DEFAULT 1,
  [CreatedAt]   DATETIME2 DEFAULT GETDATE(),
  [UniqueToken] UNIQUEIDENTIFIER DEFAULT NEWID(),
  [SeqToken]    UNIQUEIDENTIFIER DEFAULT NEWSEQUENTIALID() ROWGUIDCOL,
  [Photo]       VARBINARY(MAX),
  [Notes]       NVARCHAR(MAX),
  [Config]      XML,
  [Location]    GEOGRAPHY,
  [TreePath]    HIERARCHYID
) ON [PRIMARY];
GO

-- ALTER TABLE with WITH CHECK and CONSTRAINT WITH (...)
ALTER TABLE [Users] WITH CHECK
  ADD CONSTRAINT [chk_active] CHECK ([IsActive] IN (0,1));
GO

-- Multi-statement batches separated by GO are honored
CREATE TABLE [dbo].[Orders] (
  [OrderID] INT IDENTITY NOT NULL PRIMARY KEY  -- bare IDENTITY → (1,1)
);
GO

-- PostgreSQL / Standard SQL: double quotes
CREATE TABLE "My Table" (
  "Column Name" INTEGER
);

-- MySQL: backtick quotes
CREATE TABLE `my_table` (
  `column_name` INT
);

-- MSSQL / SQL Server: square brackets
CREATE TABLE [my_table] (
  [column_name] INT
);