FlowToolkit
Dev

Database Seeder

Generate realistic SQL INSERT statements for development and testing.

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About this tool

Define your table schema — columns, types, lengths, nullability — and generate bulk INSERT statements for MySQL, PostgreSQL, SQLite, and SQL Server. Optionally include a DROP TABLE and CREATE TABLE prefix. Choose between multi-row INSERT syntax or individual statements. All data generation runs locally, no upload required.

Why seed a database?

Every developer needs test data — for a local development environment, a staging server, a demo instance, or a CI pipeline. Hand-typing SQL INSERT statements is tedious and unrealistic. Real-world data has patterns: names, dates, diverse values, occasional nulls. A seeder produces data that looks and behaves like production data without the risk of using actual production records.

The Database Seeder generates SQL directly, so the output works in any SQL client, migration script, or Docker entrypoint. Combine it with your existing schema — just define the columns you need and let the tool produce the INSERT statements.

How it works

Define your table name and add columns one by one. For each column, pick a type (VARCHAR, INT, DECIMAL, BOOLEAN, DATE, etc.), set a name, and configure type-specific options like character length or decimal precision. Toggle nullability — nullable columns randomly produce NULL values to mimic real-world sparse data.

When you click Generate, the tool produces a complete SQL script: optionally a DROP TABLE IF EXISTS, optionally a CREATE TABLE statement, and then the INSERT statements. Multi-row INSERT batches all rows into a single statement for MySQL, PostgreSQL, and SQLite; individual INSERTs are used for SQL Server.

Use cases

  • Filling a local development database with realistic data for frontend and API testing.
  • Generating seed SQL files for Docker Compose or CI/CD pipeline setup scripts.
  • Creating demo datasets for product walkthroughs, training environments, or conference booths.
  • Populating test fixtures for integration tests with controlled, reproducible data.
  • Generating bulk INSERT scripts for load testing and performance benchmarking.

Dialect differences

Identifier quoting follows each dialect: backticks for MySQL, double quotes for PostgreSQL, square brackets for SQL Server. SQLite accepts bare identifiers. Multi-row INSERT (VALUES (...), (...), ...) is supported by MySQL, PostgreSQL, and SQLite; SQL Server requires individual INSERT statements and the tool switches automatically.

Type syntax is adjusted per dialect where relevant. The generated SQL is intended as a starting point — review the output and adjust column types to match your exact schema.

Frequently asked questions

What databases are supported?

MySQL, PostgreSQL, SQLite, and SQL Server. The tool adapts identifier quoting and INSERT syntax to each dialect.

What column types can I generate?

VARCHAR (with custom length), INT, BIGINT, DECIMAL (with precision and scale), FLOAT, BOOLEAN, DATE, DATETIME, TEXT, EMAIL (generates realistic email addresses), and UUID.

Can I include CREATE TABLE?

Yes. Toggle "CREATE TABLE" on to include the full CREATE statement before the INSERTs. You can also enable "DROP TABLE IF EXISTS" to start fresh.

What is multi-row INSERT syntax?

Instead of one INSERT per row, multi-row mode generates a single INSERT with multiple value tuples — faster for bulk imports. SQL Server does not support this syntax, so multi-row is disabled for that dialect.

Can I mark columns as nullable?

Yes. Each column has a NULL toggle. Nullable columns occasionally generate NULL values; non-nullable columns always get a value.

Is my schema sent anywhere?

No. Everything runs entirely in your browser. No schema, data, or SQL is uploaded.

How many rows can I generate?

Up to 10,000 rows in a single generation. For larger datasets, generate multiple batches.

Can I generate UUIDs as primary keys?

Yes. Choose the UUID column type to generate random UUID v4 values, ideal for primary key seeding.