sqlc/docs/tutorials/getting-started-postgresql.md

Getting started with PostgreSQL

This tutorial assumes that the latest version of sqlc is installed and ready to use.

Create a new directory called sqlc-tutorial and open it up.

Initialize a new Go module named tutorial.sql.dev/app

go mod init tutorial.sqlc.dev/app

sqlc looks for either a sqlc.yaml or sqlc.json file in the current directory. In our new directory, create a file named sqlc.yaml with the following contents:

version: 1
packages:
  - path: "tutorial"
    name: "tutorial"
    engine: "postgresql"
    schema: "schema.sql"
    queries: "query.sql"

sqlc needs to know your database schema and queries. In the same directory, create a file named schema.sql with the following contents:

CREATE TABLE authors (
  id   BIGSERIAL PRIMARY KEY,
  name text      NOT NULL,
  bio  text
);

Next, create a query.sql file with the following four queries:

-- name: GetAuthor :one
SELECT * FROM authors
WHERE id = $1 LIMIT 1;

-- name: ListAuthors :many
SELECT * FROM authors
ORDER BY name;

-- name: CreateAuthor :one
INSERT INTO authors (
  name, bio
) VALUES (
  $1, $2
)
RETURNING *;

-- name: DeleteAuthor :exec
DELETE FROM authors
WHERE id = $1;

You are now ready to generate code. Run the generate command. You shouldn't see any errors or output.

sqlc generate

You should now have a tutorial package containing three files.

├── go.mod
├── query.sql
├── schema.sql
├── sqlc.yaml
└── tutorial
    ├── db.go
    ├── models.go
    └── query.sql.go

You can use your newly generated queries in app.go.

package main

import (
	"context"
	"database/sql"
	"log"
	"reflect"

	"tutorial.sqlc.dev/app/tutorial"

	_ "github.com/lib/pq"
)

func run() error {
	ctx := context.Background()

	db, err := sql.Open("postgres", "user=pqgotest dbname=pqgotest sslmode=verify-full")
	if err != nil {
		return err
	}

	queries := tutorial.New(db)

	// list all authors
	authors, err := queries.ListAuthors(ctx)
	if err != nil {
		return err
	}
	log.Println(authors)

	// create an author
	insertedAuthor, err := queries.CreateAuthor(ctx, tutorial.CreateAuthorParams{
		Name: "Brian Kernighan",
		Bio:  sql.NullString{String: "Co-author of The C Programming Language and The Go Programming Language", Valid: true},
	})
	if err != nil {
		return err
	}
	log.Println(insertedAuthor)

	// get the author we just inserted
	fetchedAuthor, err := queries.GetAuthor(ctx, insertedAuthor.ID)
	if err != nil {
		return err
	}

	// prints true
	log.Println(reflect.DeepEqual(insertedAuthor, fetchedAuthor))
	return nil
}

func main() {
	if err := run(); err != nil {
		log.Fatal(err)
	}
}

Before the code will compile, you'll need to add the Go PostgreSQL driver.

go get github.com/lib/pq
go build ./...

To make that possible, sqlc generates readable, idiomatic Go code that you otherwise would have had to write yourself. Take a look in tutorial/query.sql.go.