Can my DB?

CREATE TABLE IF NOT EXISTS users (
  id SERIAL PRIMARY KEY,
  email TEXT NOT NULL
);

DROP TABLE IF EXISTS users;

• Broad coverage: CREATE IF NOT EXISTS on tables, indexes, schemas, sequences; DROP IF EXISTS on most object types.
• ALTER TABLE ADD COLUMN IF NOT EXISTS since 9.6.
• CREATE TABLE IF NOT EXISTS only checks the name — it does not reconcile column definitions against the existing table.

CREATE TABLE IF NOT EXISTS users (
  id INT AUTO_INCREMENT PRIMARY KEY,
  email VARCHAR(255) NOT NULL
);

DROP TABLE IF EXISTS users;

• Available on CREATE / DROP for TABLE, DATABASE, INDEX, VIEW, and DROP PROCEDURE.
• CREATE TABLE IF NOT EXISTS emits a warning (not an error) when the table already exists.

CREATE TABLE IF NOT EXISTS users (
  id INT AUTO_INCREMENT PRIMARY KEY,
  email VARCHAR(255) NOT NULL
);

DROP TABLE IF EXISTS users;

• Same IF EXISTS / IF NOT EXISTS coverage as MySQL, plus CREATE OR REPLACE on tables, views, triggers, and procedures for idempotent DDL.

CREATE TABLE IF NOT EXISTS users (
  id NUMBER GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  email VARCHAR2(255) NOT NULL
);

DROP TABLE IF EXISTS users;

• Added in 23c on CREATE TABLE, DROP TABLE, and several other DDL statements.
• Pre-23c, use PL/SQL with ORA-00942 / ORA-00955 exception handling, or pre-check USER_TABLES.

IF OBJECT_ID('dbo.users', 'U') IS NULL
BEGIN
  CREATE TABLE dbo.users (
    id INT IDENTITY PRIMARY KEY,
    email NVARCHAR(255) NOT NULL
  );
END;

DROP TABLE IF EXISTS dbo.users;

• DROP ... IF EXISTS on tables, indexes, and procedures arrived in 2016.
• No CREATE TABLE IF NOT EXISTS. The T-SQL idiom for conditional CREATE is IF OBJECT_ID(name, 'U') IS NULL BEGIN CREATE TABLE ... END.

CREATE TABLE IF NOT EXISTS users (
  id INTEGER PRIMARY KEY,
  email TEXT NOT NULL
);

DROP TABLE IF EXISTS users;

• Long-standing. Available on CREATE / DROP for tables, indexes, views, and triggers.

CREATE TABLE IF NOT EXISTS users (
  id INT IDENTITY PRIMARY KEY,
  email VARCHAR(255) NOT NULL
);

DROP TABLE IF EXISTS users;

• Same syntax as PostgreSQL across CREATE / DROP for tables, views, and related objects.

CREATE TABLE IF NOT EXISTS users (
  id INT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  email VARCHAR(255) NOT NULL
);

DROP TABLE IF EXISTS users;

• CREATE TABLE IF NOT EXISTS arrived in 11.1; DROP TABLE IF EXISTS in recent versions.
• Pre-11.1, check SYSCAT.TABLES before running DDL.

CREATE TABLE IF NOT EXISTS users (
  id INT AUTOINCREMENT PRIMARY KEY,
  email VARCHAR(255) NOT NULL
);

DROP TABLE IF EXISTS users;

• Available on CREATE, DROP, and ALTER across every object type (TABLE, VIEW, SCHEMA, DATABASE, WAREHOUSE, ...).

CREATE TABLE IF NOT EXISTS users (
  id INT64,
  email STRING NOT NULL
);

DROP TABLE IF EXISTS users;

• Available on CREATE / DROP for tables, views, and related objects.