Add insert with VALUES and functions call example

examples/insert_values_and_functions.ts

@@ -0,0 +1,95 @@
+import type { ClickHouseSettings } from '@clickhouse/client'
+import { createClient } from '@clickhouse/client' // or '@clickhouse/client-web'
+
+type Data = {
+  id: string
+  timestamp: number
+  email: string
+  name: string | null
+}
+
+/**
+ * An example how to send an INSERT INTO ... VALUES ... query that requires additional functions call.
+ * Inspired by https://github.com/ClickHouse/clickhouse-js/issues/239
+ */
+void (async () => {
+  const tableName = 'insert_values_and_functions'
+  const client = createClient()
+  // Recommended for cluster usage to avoid situations where a query processing error occurred after the response code
+  // and HTTP headers were sent to the client, as it might happen before the changes were applied on the server.
+  // See https://clickhouse.com/docs/en/interfaces/http/#response-buffering
+  const commandSettings: ClickHouseSettings = {
+    wait_end_of_query: 1,
+  }
+
+  // Prepare an example table
+  await client.command({
+    query: `DROP TABLE IF EXISTS ${tableName}`,
+    clickhouse_settings: commandSettings,
+  })
+  await client.command({
+    query: `
+      CREATE TABLE ${tableName} (
+        id String,
+        timestamp DateTime64(3, 'UTC'),
+        email String,
+        name Nullable(String)
+      )
+      ENGINE MergeTree()
+      ORDER BY (id)
+    `,
+    clickhouse_settings: commandSettings,
+  })
+
+  // Here we are assuming that we are getting these rows from somewhere...
+  const rows = getRows(20_000)
+
+  // Generate the query and insert the values
+  const insertQuery = `
+    INSERT INTO ${tableName}
+      (id, timestamp, email, name)
+    VALUES
+      ${rows.map((r) => toInsertValue(r)).join(',')}
+  `
+  await client.command({
+    query: insertQuery,
+    clickhouse_settings: commandSettings,
+  })
+
+  // Get a few back and print those rows to check what was inserted
+  const sampleResultSet = await client.query({
+    query: `SELECT * FROM ${tableName} ORDER BY rand() LIMIT 3`,
+    format: 'JSONEachRow',
+  })
+  console.info(`Sample inserted rows:`)
+  const sampleRows = await sampleResultSet.json<Data[]>()
+  sampleRows.forEach((row) => {
+    console.info(row)
+  })
+
+  // Close it during your application graceful shutdown
+  await client.close()
+})()
+
+function getRows(n: number): Data[] {
+  const now = Date.now() // UNIX timestamp in milliseconds
+  return [...new Array(n)].map((_, i) => ({
+    id: Buffer.from(i.toString(10)).toString('hex'),
+    timestamp: now - i * 1000, // subtract one second for each row
+    email: `email${i}@example.com`,
+    name: i % 2 === 0 ? `Name${i}` : null, // for every second row it is NULL
+  }))
+}
+
+// Generates something like:
+// (unhex('42'), '1623677409123', '[email protected]', 'Name')
+// or
+// (unhex('144'), '1623677409123', '[email protected]', NULL)
+// if name is null.
+function toInsertValue(row: Data): string {
+  const id = `unhex('${row.id}')`
+  const timestamp = `'${row.timestamp}'`
+  const email = `'${row.email}'`
+  const name = row.name === null ? 'NULL' : `'${row.name}'`
+  return `(${id}, ${timestamp}, ${email}, ${name})`
+}