diff --git a/src/index.ts b/src/index.ts
index 7f3149f..74b961d 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -5,6 +5,36 @@ import readline from 'node:readline'
 import oracledb from 'oracledb'
 import { findUpSync } from 'find-up'
 
+interface OraTable {
+  OWNER: string
+  TABLE_NAME: string
+}
+
+interface OraColumn {
+  OWNER: string
+  TABLE_NAME: string
+  COLUMN_NAME: string
+  DATA_TYPE: string
+  DATA_LENGTH: number | null
+  NULLABLE: 'Y' | 'N'
+}
+
+interface Schema {
+  tables: Table[]
+}
+
+interface Table {
+  owner: string
+  name: string
+  columns: Column[]
+}
+
+interface Column {
+  name: string
+  datatype: string
+  nullable: boolean
+}
+
 function getStringParts(str: string, offset: number) {
   const init = str.slice(0, offset)
 
@@ -43,10 +73,96 @@ async function main() {
     prompt: `${user}@${connectString}> `,
     removeHistoryDuplicates: true,
     history,
+    completer(linePartial: string) {
+      const words = [...rl.line.matchAll(/[a-zA-Z0-9_.$]+/g).map((g) => g[0])]
+      words.push(...words.map((w) => w.toUpperCase()))
+      const wset = new Set(words)
+
+      const completions = ['DUAL']
+      const tables = schema.tables.filter((tab) => {
+        if (tab.owner) {
+          const fullName = `${tab.owner}.${tab.name}`
+          completions.push(fullName)
+          if (wset.has(fullName)) {
+            return true
+          }
+        }
+
+        if (['', 'SYS', 'WMSYS'].includes(tab.owner)) {
+          completions.push(tab.name)
+          return wset.has(tab.name)
+        }
+      })
+
+      for (const tab of tables) {
+        for (const col of tab.columns) {
+          completions.push(col.name)
+        }
+      }
+
+      completions.sort()
+
+      const suffix = linePartial.match(/[a-zA-Z0-9_$]*.$/)?.[0] ?? ''
+      const upper = suffix.toUpperCase()
+      const prefix = linePartial.substring(0, linePartial.length - suffix.length)
+
+      return [
+        completions
+          .filter((comp) => comp.startsWith(suffix) || comp.startsWith(upper))
+          .map((comp) => prefix + comp),
+        linePartial,
+      ]
+    },
   })
 
   const connection = await oracledb.getConnection({ user, password, connectString })
 
+  function execute<R>(query: string, args: any[] = [], maxRows?: number) {
+    return connection.execute<R>(query, args, {
+      dbObjectAsPojo: true,
+      prefetchRows: 1024,
+      fetchArraySize: 1024,
+      maxRows,
+      outFormat: oracledb.OUT_FORMAT_OBJECT,
+      resultSet: false,
+    })
+  }
+
+  const schema: Schema = { tables: [] }
+
+  async function refresh() {
+    const tables = await execute<OraTable>(
+      `
+        select owner, table_name from all_tables
+        union all select owner, view_name table_name from all_views
+        union all select '' owner, table_name from user_tables
+        union all select '' owner, view_name table_name from user_views
+      `,
+    )
+
+    const columns = await execute<OraColumn>(
+      'select owner, table_name, column_name, data_type, data_length, nullable from all_tab_cols',
+    )
+
+    schema.tables.length = 0
+
+    for (const table of tables.rows ?? []) {
+      schema.tables.push({
+        owner: table.OWNER ?? '',
+        name: table.TABLE_NAME,
+        columns: (columns.rows ?? [])
+          .filter((col) => col.OWNER === table.OWNER && col.TABLE_NAME === table.TABLE_NAME)
+          .map((col) => ({
+            name: col.COLUMN_NAME,
+            datatype:
+              col.DATA_LENGTH === null ? col.DATA_TYPE : `${col.DATA_TYPE}(${col.DATA_LENGTH})`,
+            nullable: col.NULLABLE === 'Y',
+          })),
+      })
+    }
+  }
+
+  await refresh()
   rl.prompt()
 
   let displayMode: 'table' | 'list' = 'table'
@@ -66,18 +182,7 @@ async function main() {
       process.exit(0)
     } else if (query) {
       try {
-        const result = await connection.execute(
-          query,
-          {},
-          {
-            dbObjectAsPojo: true,
-            prefetchRows: 1024,
-            fetchArraySize: 1024,
-            maxRows: 1024,
-            outFormat: oracledb.OUT_FORMAT_OBJECT,
-            resultSet: false,
-          },
-        )
+        const result = await execute(query, [], 1024)
         if (result.rows && result.rows.length > 0) {
           if (displayMode === 'table') {
             console.table(result.rows)