sql(mysql): the default database is mysql again

As before this branch and as the docs say. `mariadb://` without a database still selects none: its old
default, a database named `mariadb`, exists on no server unless somebody creates it, so the connection
failed with 1049.

docs/runtime/sql.mdx

@@ -422,7 +422,7 @@ Call `.raw()` before the query starts, that is before `await`, `.then()` or `.ex
 
 ### Result metadata
 
-The array that a query resolves to has six more properties. They are not enumerable, so `console.log`, `Object.keys`, `JSON.stringify` and spreading only see the rows.
+The array that a query resolves to has six more properties. `console.log`, `Object.keys` and spreading list `count`, `command`, `lastInsertRowid` and `affectedRows` next to the rows. `columns` and `statement` are not enumerable, and `JSON.stringify` only sees the rows.
 
 | Property          | Meaning                                                        | PostgreSQL                                              | MySQL / MariaDB                                            | SQLite                                                                   |
 | ----------------- | -------------------------------------------------------------- | ------------------------------------------------------- | ---------------------------------------------------------- | ------------------------------------------------------------------------ |
@@ -819,13 +819,13 @@ An `sslmode` in the URL takes priority over both, and a mode in the `tls` or `ss
 
 ### MySQL and MariaDB Environment Variables
 
-| MySQL            | MariaDB            | Default Value | Description                                                |
-| ---------------- | ------------------ | ------------- | ---------------------------------------------------------- |
-| `MYSQL_HOST`     | `MARIADB_HOST`     | `localhost`   | Database host                                              |
-| `MYSQL_PORT`     | `MARIADB_PORT`     | `3306`        | Database port                                              |
-| `MYSQL_USER`     | `MARIADB_USER`     | `root`        | Database user. Bun reads `USER`, then `USERNAME`, after it |
-| `MYSQL_PASSWORD` | `MARIADB_PASSWORD` | (empty)       | Database password                                          |
-| `MYSQL_DATABASE` | `MARIADB_DATABASE` | (none)        | Database name                                              |
+| MySQL            | MariaDB            | Default Value   | Description                                                |
+| ---------------- | ------------------ | --------------- | ---------------------------------------------------------- |
+| `MYSQL_HOST`     | `MARIADB_HOST`     | `localhost`     | Database host                                              |
+| `MYSQL_PORT`     | `MARIADB_PORT`     | `3306`          | Database port                                              |
+| `MYSQL_USER`     | `MARIADB_USER`     | `root`          | Database user. Bun reads `USER`, then `USERNAME`, after it |
+| `MYSQL_PASSWORD` | `MARIADB_PASSWORD` | (empty)         | Database password                                          |
+| `MYSQL_DATABASE` | `MARIADB_DATABASE` | `mysql`, (none) | Database name                                              |
 
 These variables do not select the adapter. Bun reads them for a client that is already MySQL or MariaDB, through its URL or the `adapter` option.
 
@@ -896,7 +896,7 @@ You can configure the connection manually by passing options to the `SQL` constr
 | `port`                    | `5432` or `3306`          | Database port                                                                                                     |
 | `username`                | `postgres` or `root`      | Database user                                                                                                     |
 | `password`                | (empty)                   | A string, or a [function](#dynamic-passwords) that returns one                                                    |
-| `database`                | PostgreSQL: the user name | Database name. MySQL and MariaDB select none by default                                                           |
+| `database`                | PostgreSQL: the user name | Database name. MySQL: `mysql`. MariaDB selects none by default                                                    |
 | `path`                    |                           | Unix socket to use instead of TCP. `socket` is an alias. On PostgreSQL, a directory gets `/.s.PGSQL.<port>` added |
 | `tls`                     | `false`                   | `true`, an [SSL mode](#ssl-modes-overview), TLS options, or a `BunFile` with the CA certificate                   |
 | `max`                     | `10`                      | Maximum number of connections in the [pool](#connection-pooling)                                                  |

packages/bun-types/sql.d.ts

@@ -498,7 +498,7 @@ declare module "bun" {
       /**
        * Name of the database to connect to. `PGDATABASE`, `MYSQL_DATABASE` and
        * `MARIADB_DATABASE` take priority over the database in a URL.
-       * @default The username value for PostgreSQL. MySQL and MariaDB select no database
+       * @default The username value for PostgreSQL, `"mysql"` for MySQL. MariaDB selects no database
        */
       database?: string | undefined;
 

src/js/internal/sql/options.ts

@@ -684,7 +684,7 @@ function parseOptions(
     envOf(prefix, "DATABASE") ||
     query.database ||
     (!isUnixUrl && decodeIfValid(urlPathname.slice(1))) ||
-    (isPostgres ? username : "");
+    (isPostgres ? username : adapter === "mysql" ? "mysql" : "");
 
   let path =
     options.path ||

test/js/sql/adapter-env-var-precedence.test.ts

@@ -255,9 +255,12 @@ describe("SQL adapter environment variable precedence", () => {
     expect(options.options.username).toBe("mysql-user");
   });
 
-  test.each(["mysql", "mariadb"] as const)("%s selects no database by default", adapter => {
-    expect(new SQL({ adapter, hostname: "localhost" }).options.database).toBe("");
-    expect(new SQL(`${adapter}://root@localhost/`).options.database).toBe("");
+  test.each([
+    ["mysql", "mysql"],
+    ["mariadb", ""],
+  ] as const)("%s: the default database is %p", (adapter, database) => {
+    expect(new SQL({ adapter, hostname: "localhost" }).options.database).toBe(database);
+    expect(new SQL(`${adapter}://root@localhost/`).options.database).toBe(database);
   });
 
   test("should default to username as database name for PostgreSQL adapter", () => {
@@ -1241,7 +1244,7 @@ describe("SQL adapter environment variable precedence", () => {
         "{ adapter: 'mysql' }: a PostgreSQL DATABASE_URL counts as not set",
         { DATABASE_URL: pg },
         [{ adapter: "mysql" }],
-        { adapter: "mysql", hostname: "localhost", port: 3306, username: "root", password: "", database: "" },
+        { adapter: "mysql", hostname: "localhost", port: 3306, username: "root", password: "", database: "mysql" },
       ],
       [
         "{ adapter: 'postgres' }: a MySQL TLS_DATABASE_URL counts as not set, except for the TLS in its name",
@@ -1284,7 +1287,7 @@ describe("SQL adapter environment variable precedence", () => {
     // `adapter` passes over the URL of another adapter's server. The server is not dialed and gets no credentials,
     // but the connection is as well protected as that URL asks for.
     const localPostgres = { adapter: "postgres", hostname: "localhost", port: 5432, password: "" };
-    const localMySQL = { adapter: "mysql", hostname: "localhost", port: 3306, password: "", database: "" };
+    const localMySQL = { adapter: "mysql", hostname: "localhost", port: 3306, password: "", database: "mysql" };
     const postgres = [{ adapter: "postgres" }] as Row[2];
     const mysql = [{ adapter: "mysql" }] as Row[2];
     test.each<Row>([
@@ -1409,7 +1412,7 @@ describe("SQL adapter environment variable precedence", () => {
         defaultPort,
         defaultUser,
         "",
-        adapter === "postgres" ? defaultUser : "",
+        adapter === "postgres" ? defaultUser : adapter === "mysql" ? "mysql" : "",
       ]);
 
       setEnv(prefix, "e");

test/js/sql/sql-mysql.test.ts

@@ -612,11 +612,14 @@ console.log(JSON.stringify({ outcome, closed }));`,
         Bun.inspect(result);
       });
 
-      test.each(["mysql", "mariadb"])("%s:// without a database name selects no database", async scheme => {
+      test.each([
+        ["mysql", "mysql"],
+        ["mariadb", null],
+      ])("%s:// without a database name selects %p", async (scheme, selected) => {
         const url = `${scheme}://root:${password}@${container.host}:${container.port}`;
         for (const suffix of ["", "/"]) {
           await using db = new SQL({ ...getOptions(), url: url + suffix });
-          expect(await db`select database() as db`).toEqual([{ db: null }]);
+          expect(await db`select database() as db`).toEqual([{ db: selected }]);
         }
       });