How to seed data with Knex — Basic

SQL / Knex Migrations / seeds

Populate tables with initial or test data using Knex seed scripts.

Learn: Seeds load repeatable test or demo data after migrations. Keep seeds idempotent where possible (delete then insert, or use upsert patterns) so `knex seed:run` is safe locally.

Supplementary examples

Seed function

exports.seed = async function (knex) {
  await knex("users").del();
  await knex("users").insert([
    { username: "demo" },
    { username: "tester" },
  ]);
};

Course example

exports.seed = function (knex) {
// Deletes ALL existing entries
return knex("table_name")
.del()
.then(function () {
// Inserts seed entries
return knex("table_name").insert([
{ id: 1, colName: "rowValue1" },
{ id: 2, colName: "rowValue2" },
{ id: 3, colName: "rowValue3" },
]);
});
};

Additional references & examples

Knex.js documentation
Query builder, migrations, seeds, and connection configuration.
Knex seeds
Populate tables with initial or test data.