Add database SQL export action

tests/databaseExport.test.ts

@@ -0,0 +1,96 @@
+import { strict as assert } from "node:assert";
+import test from "node:test";
+import {
+  DATABASE_EXPORT_INSERT_BATCH_SIZE,
+  DATABASE_EXPORT_ROW_LIMIT,
+  buildExportPageSql,
+  buildDatabaseSqlExport,
+  buildInsertStatements,
+  formatSqlLiteral,
+} from "../src/lib/databaseExport.ts";
+
+test("formats SQL literals for exported INSERT statements", () => {
+  assert.equal(formatSqlLiteral(null), "NULL");
+  assert.equal(formatSqlLiteral(42), "42");
+  assert.equal(formatSqlLiteral(true), "TRUE");
+  assert.equal(formatSqlLiteral("O'Hara"), "'O''Hara'");
+});
+
+test("builds batched INSERT statements for one exported table", () => {
+  const statements = buildInsertStatements({
+    qualifiedTableName: "`users`",
+    columns: ["id", "name"],
+    rows: [
+      [1, "Ada"],
+      [2, "O'Hara"],
+      [3, "Linus"],
+    ],
+    quoteIdentifier: (name) => `\`${name}\``,
+    batchSize: 2,
+  });
+
+  assert.deepEqual(statements, [
+    "INSERT INTO `users` (`id`, `name`) VALUES (1, 'Ada'), (2, 'O''Hara');",
+    "INSERT INTO `users` (`id`, `name`) VALUES (3, 'Linus');",
+  ]);
+});
+
+test("builds capped export page queries", () => {
+  assert.equal(
+    buildExportPageSql({
+      databaseType: "mysql",
+      tableName: "users",
+      limit: 500,
+      offset: 1000,
+    }),
+    "SELECT * FROM `users` LIMIT 500 OFFSET 1000;",
+  );
+
+  assert.equal(
+    buildExportPageSql({
+      databaseType: "sqlserver",
+      schema: "dbo",
+      tableName: "accounts",
+      limit: DATABASE_EXPORT_ROW_LIMIT,
+    }),
+    `SELECT TOP ${DATABASE_EXPORT_ROW_LIMIT} * FROM "dbo"."accounts"`,
+  );
+});
+
+test("builds a database SQL export with DDL before data", () => {
+  const sql = buildDatabaseSqlExport({
+    databaseName: "app",
+    exportedAt: new Date("2026-05-02T00:00:00.000Z"),
+    rowLimitPerTable: DATABASE_EXPORT_ROW_LIMIT,
+    tables: [
+      {
+        displayName: "users",
+        qualifiedTableName: "`users`",
+        ddl: "CREATE TABLE `users` (`id` int);",
+        columns: ["id"],
+        rows: [[1]],
+        truncated: true,
+      },
+    ],
+    quoteIdentifier: (name) => `\`${name}\``,
+    insertBatchSize: DATABASE_EXPORT_INSERT_BATCH_SIZE,
+  });
+
+  assert.equal(
+    sql,
+    [
+      "-- DBX database export",
+      "-- Database: app",
+      "-- Exported at: 2026-05-02T00:00:00.000Z",
+      `-- Row limit per table: ${DATABASE_EXPORT_ROW_LIMIT}`,
+      "",
+      "-- Structure for users",
+      "CREATE TABLE `users` (`id` int);",
+      "",
+      "-- Data for users",
+      `-- Exported rows: 1 (truncated at ${DATABASE_EXPORT_ROW_LIMIT})`,
+      "INSERT INTO `users` (`id`) VALUES (1);",
+      "",
+    ].join("\n"),
+  );
+});