# Getting Started

This page takes you from installation to a first query with the smallest working `@pardnchiu/mysql-pool` setup.

## Prerequisites

| Item | Version |
|---|---|
| Node.js | 20 or higher (`engines.node` in `package.json`) |
| MySQL | 8.0 or higher; only `total()` needs the `COUNT(*) OVER()` window function, so 5.7 works without it |
| mysql2 | ^3.14.1, installed with the package |

## Installation

```bash
npm install @pardnchiu/mysql-pool
```

## Configure the Connection

The quickest route is environment variables. When only one side is set, the other side creates no pool; see [Read-Write Pools](/read-write-pools).

```bash
export DB_READ_HOST=127.0.0.1
export DB_READ_USER=reader
export DB_READ_PASSWORD=secret
export DB_READ_DATABASE=app

export DB_WRITE_HOST=127.0.0.1
export DB_WRITE_USER=writer
export DB_WRITE_PASSWORD=secret
export DB_WRITE_DATABASE=app
```

You can also pass a config object to `init()`; see [Configuration](/configuration) for every field.

## First Query

```typescript
import MySQLPool from "@pardnchiu/mysql-pool";

async function main() {
  try {
    // Create both pools and check out one connection from each
    await MySQLPool.init();

    // Uses the read pool by default
    const users = await MySQLPool
      .table("users")
      .select("id", "name")
      .where("status", "active")
      .limit(10)
      .get();

    console.log(users);
  } catch (err) {
    console.error("query failed:", err);
  } finally {
    await MySQLPool.close();
  }
}

main();
```

When `init()` cannot reach the database it prints `MySQL initialization failed:` through `console.error` and rethrows the original error (`src/MySQLPool.ts:93`).

## First Write

```typescript
const id = await MySQLPool
  .table("users")
  .insert({ name: "John Doe", email: "john@example.com" });

await MySQLPool
  .table("users")
  .where("id", id)
  .update({ updated_at: "NOW()" });
```

`insert()`, `update()`, and `upsert()` always use the write pool regardless of the second argument to `table()`.

## Next Steps

- [Builder State](/builder-state): why every chain starts with `table()`
- [Select and Where](/select-and-where): every form of `where()`