Indexes & Constraints

Constraints

SQL constraints are the rules enforced on data columns on table.
These are used to prevent invalid data from being entered into the database.
This ensures the accuracy and reliability of the data in the database.

Default

The DEFAULT clause specifies a default value to use for the column if no value is explicitly provided by the user when doing an INSERT. If there is no explicit DEFAULT clause attached to a column definition, then the default value of the column is NULL.

An explicit DEFAULT clause may specify that the default value is NULL, a string constant, a blob constant, a signed-number, or any constant expression enclosed in parentheses.

import { sql } from "drizzle-orm";
import { integer, uuid, pgTable } from "drizzle-orm/pg-core";
 
const table = pgTable('table', {
  integer1: integer('integer1').default(42),
  integer2: integer('integer2').default(sql`'42'::integer`),
  uuid1: uuid('uuid1').defaultRandom(),
  uuid2: uuid('uuid2').default(sql`get_random_uuid()`),
});

CREATE TABLE IF NOT EXISTS "table" (
  "integer1" integer DEFAULT 42,
  "integer2" integer DEFAULT '42'::integer,
  "uuid1" uuid DEFAULT gen_random_uuid(),
  "uuid2" uuid DEFAULT gen_random_uuid()
);

Not null

By default, a column can hold NULL values.
The NOT NULL constraint enforces a column to NOT accept NULL values.
This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field.

import { integer, sqliteTable } from "drizzle-orm/pg-core";
 
const table = pgTable('table', {
  integer: integer('integer').notNull(),
});

CREATE TABLE IF NOT EXISTS "table" (
  "integer" integer NOT NULL,
);

Unique

The UNIQUE constraint ensures that all values in a column are different.
Both the UNIQUE and PRIMARY KEY constraints provide a guarantee for uniqueness for a column or set of columns.
A PRIMARY KEY constraint automatically has a UNIQUE constraint.
However, you can have many UNIQUE constraints per table, but only one PRIMARY KEY constraint per table.

NOT YET IMPLEMENTED IN DRIZZLE ORM

Check

The CHECK constraint is used to limit the value range that can be placed in a column.
If you define a CHECK constraint on a column it will allow only certain values for this column.
If you define a CHECK constraint on a table it can limit the values in certain columns based on values in other columns in the row.

NOT YET IMPLEMENTED IN DRIZZLE ORM

Primary Key

The PRIMARY KEY constraint uniquely identifies each record in a table.
Primary keys must contain UNIQUE values, and cannot contain NULL values.
A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).

import { serial, text, pgTable } from "drizzle-orm/pg-core";
 
const user = pgTable('user', {
  id: serial('id').primaryKey(),
});
 
const table = pgTable('table', {
  id: text('cuid').primaryKey(),
});

CREATE TABLE IF NOT EXISTS "user" (
  "id" serial PRIMARY KEY,
);
 
CREATE TABLE IF NOT EXISTS "table" (
  "cuid" text PRIMARY KEY,
);

Composite Primary Key

Just like PRIMARY KEY, composite primary key uniquely each record in a table using multiple fields
Drizzle ORM provides a standalone primaryKey operator for that

import { serial, text, integer, primaryKey, pgTable } from "drizzle-orm/pg-core";
 
export const user = pgTable("user", {
  id: serial("id").primaryKey(),
  name: text("name"),
});
 
export const book = pgTable("book", {
  id: serial("id").primaryKey(),
  name: text("name"),
});
 
export const booksToAuthors = pgTable("books_to_authors", {
  authorId: integer("author_id"),
  bookId: integer("book_id"),
}, (table) => {
  return {
    pk: primaryKey(table.bookId, table.authorId),
  };
});

...
 
CREATE TABLE IF NOT EXISTS "books_to_authors" (
  "author_id" integer,
  "book_id" integer,
  PRIMARY KEY("book_id","author_id")
);

Foreign key

The FOREIGN KEY constraint is used to prevent actions that would destroy links between tables. A FOREIGN KEY is a field (or collection of fields) in one table, that refers to the PRIMARY KEY in another table. The table with the foreign key is called the child table, and the table with the primary key is called the referenced or parent table.

Drizzle ORM provides several ways to declare foreign keys
You can declare them in a column declaration statement

import { serial, text, integer, pgTable } from "drizzle-orm/pg-core";
 
export const user = pgTable("user", {
  id: serial("id"),
  name: text("name"),
});
 
export const book = pgTable("book", {
  id: serial("id"),
  name: text("name"),
  authorId: integer("author_id").references(() => user.id)
});

If you want to do a self reference, due to a TypeScript limitations you will have to either explicitly set return type for reference callback or user a standalone foreignKey operator

import { serial, text, integer, foreignKey, pgTable, AnyPgColumn } from "drizzle-orm/pg-core";
 
export const user = pgTable("user", {
  id: serial("id"),
  name: text("name"),
  parentId: integer("parent_id").references((): AnyPgColumn => user.id)
});
 
// or
export const user = pgTable("user", {
  id: serial("id"),
  name: text("name"),
  parentId: integer("parent_id"),
}, (table) => {
  return {
    parentReference: foreignKey({
      columns: [table.parentId],
      foreignColumns: [table.id],
    }),
  };
});

To declare multicolumn foreign keys you can use a dedicated foreignKey operator

import { serial, text, foreignKey, pgTable, AnyPgColumn } from "drizzle-orm/pg-core";
 
export const user = pgTable("user", {
  firstName: text("firstName"),
  lastName: text("lastName"),
}, (table) => {
  return {
    pk: primaryKey(table.firstName, table.lastName),
  };
});
 
export const profile = pgTable("profile", {
  id: serial("id").primaryKey(),
  userFirstName: text("user_first_name"),
  userLastName: text("user_last_name"),
}, (table) => {
  return {
    userReference: foreignKey({
      columns: [table.userFirstName, table.userLastName],
      foreignColumns: [user.firstName, user.lastName]
    })
  }
})

Indexes

Drizzle ORM provides API for both index and unique index declaration

import { serial, text, index, uniqueIndex, pgTable } from "drizzle-orm/pg-core";
 
export const user = pgTable("user", {
  id: serial("id").primaryKey(),
  name: text("name"),
  email: text("email"),
}, (table) => {
  return {
    nameIdx: index("name_idx").on(table.name),
    emailIdx: uniqueIndex("email_idx").on(table.email),
  };
});

CREATE TABLE "user" (
  ...
);
 
CREATE INDEX "name_idx" ON "user" ("name");
CREATE UNIQUE INDEX "email_idx" ON "user" ("email");

// Index declaration reference
index('name')
  .on(table.column1, table.column2, ...) or .onOnly(table.column1, table.column2, ...)
  .concurrently()
  .using(sql``) // sql expression
  .asc() or .desc()
  .nullsFirst() or .nullsLast()
  .where(sql``) // sql expression