diff --git a/frontend/src/components/SqlEditor.tsx b/frontend/src/components/SqlEditor.tsx
index 94156ed..1cd1860 100644
--- a/frontend/src/components/SqlEditor.tsx
+++ b/frontend/src/components/SqlEditor.tsx
@@ -1,6 +1,6 @@
 import { useRef, useEffect } from 'react';
 import Editor, { Monaco, loader } from '@monaco-editor/react';
-import { databasesApi } from '@/services/api';
+import { schemaApi, TableInfo, SchemaData } from '@/services/api';
 import * as monacoEditor from 'monaco-editor';
 
 // Configure loader to use local Monaco
@@ -13,64 +13,141 @@ interface SqlEditorProps {
   height?: string;
 }
 
-// Cache for table names with 5-minute expiration
-interface TableCache {
-  tables: string[];
+// Cache for schema with 5-minute expiration
+interface SchemaCache {
+  schema: SchemaData;
   timestamp: number;
 }
 
-const tablesCache = new Map<string, TableCache>();
-const CACHE_DURATION = 5 * 60 * 1000; // 5 minutes in milliseconds
+const schemaCache = new Map<string, SchemaCache>();
+const CACHE_DURATION = 5 * 60 * 1000; // 5 minutes
 
-const getCachedTables = async (databaseId: string): Promise<string[]> => {
-  const cached = tablesCache.get(databaseId);
+const getCachedSchema = async (databaseId: string): Promise<SchemaData | null> => {
+  const cached = schemaCache.get(databaseId);
   const now = Date.now();
 
-  // Return cached data if it exists and is not expired
   if (cached && (now - cached.timestamp) < CACHE_DURATION) {
-    return cached.tables;
+    return cached.schema;
   }
 
-  // Fetch fresh data
   try {
-    const { data } = await databasesApi.getTables(databaseId);
-    tablesCache.set(databaseId, {
-      tables: data.tables,
-      timestamp: now,
-    });
-    return data.tables;
+    const { data } = await schemaApi.getSchema(databaseId);
+    if (data.success && data.data) {
+      schemaCache.set(databaseId, {
+        schema: data.data,
+        timestamp: now,
+      });
+      return data.data;
+    }
+    return null;
   } catch (error) {
-    console.error('Failed to fetch table names:', error);
-    // Return cached data if available, even if expired, as fallback
-    return cached?.tables || [];
+    console.error('Failed to fetch schema:', error);
+    return cached?.schema || null;
   }
 };
 
-// Global flag to ensure we only register the completion provider once
+// Global state for completion provider
 let completionProviderRegistered = false;
-let currentDatabaseId: string | undefined;
+let currentSchema: SchemaData | null = null;
+
+// Parse SQL to find table aliases (e.g., FROM users u, JOIN orders o)
+function parseTableAliases(sql: string): Map<string, string> {
+  const aliases = new Map<string, string>();
+
+  // Match patterns like: FROM table_name alias, FROM table_name AS alias
+  // JOIN table_name alias, JOIN table_name AS alias
+  const patterns = [
+    /(?:FROM|JOIN)\s+(\w+)(?:\s+(?:AS\s+)?(\w+))?/gi,
+    /,\s*(\w+)(?:\s+(?:AS\s+)?(\w+))?/gi,
+  ];
+
+  for (const pattern of patterns) {
+    let match;
+    while ((match = pattern.exec(sql)) !== null) {
+      const tableName = match[1].toLowerCase();
+      const alias = match[2]?.toLowerCase();
+      if (alias && alias !== 'on' && alias !== 'where' && alias !== 'join' && alias !== 'left' && alias !== 'inner' && alias !== 'right') {
+        aliases.set(alias, tableName);
+      }
+      // Also map table name to itself for direct references
+      aliases.set(tableName, tableName);
+    }
+  }
+
+  return aliases;
+}
+
+// Find tables mentioned in the query
+function findTablesInQuery(sql: string, schema: SchemaData): TableInfo[] {
+  const tables: TableInfo[] = [];
+  const sqlLower = sql.toLowerCase();
+
+  for (const table of schema.tables) {
+    if (sqlLower.includes(table.name.toLowerCase())) {
+      tables.push(table);
+    }
+  }
+
+  return tables;
+}
+
+// Get FK suggestions for ON clause
+function getFkSuggestions(
+  tablesInQuery: TableInfo[],
+  schema: SchemaData,
+  monaco: Monaco,
+  range: any
+): any[] {
+  const suggestions: any[] = [];
+
+  for (const table of tablesInQuery) {
+    for (const fk of table.foreign_keys) {
+      // Find the referenced table
+      const refTable = schema.tables.find(t => t.name === fk.references_table);
+      if (refTable && tablesInQuery.some(t => t.name === refTable.name)) {
+        const joinCondition = `${table.name}.${fk.column} = ${refTable.name}.${fk.references_column}`;
+        suggestions.push({
+          label: joinCondition,
+          kind: monaco.languages.CompletionItemKind.Snippet,
+          insertText: joinCondition,
+          detail: `FK: ${table.name} → ${refTable.name}`,
+          documentation: `Foreign key relationship`,
+          range,
+          sortText: '0' + joinCondition, // Sort FK suggestions first
+        });
+      }
+    }
+  }
+
+  return suggestions;
+}
 
 export default function SqlEditor({ value, onChange, databaseId, height }: SqlEditorProps) {
   const editorRef = useRef<any>(null);
   const monacoRef = useRef<Monaco | null>(null);
 
-  // Update current database ID when it changes
+  // Fetch schema when database changes
   useEffect(() => {
-    currentDatabaseId = databaseId;
+    if (databaseId) {
+      getCachedSchema(databaseId).then(schema => {
+        currentSchema = schema;
+      });
+    } else {
+      currentSchema = null;
+    }
   }, [databaseId]);
 
   const handleEditorDidMount = (editor: any, monaco: Monaco) => {
     editorRef.current = editor;
     monacoRef.current = monaco;
 
-    // Register completion provider only once
     if (completionProviderRegistered) {
       return;
     }
     completionProviderRegistered = true;
 
-    // Configure SQL language features
     monaco.languages.registerCompletionItemProvider('sql', {
+      triggerCharacters: ['.', ' '],
       provideCompletionItems: async (model, position) => {
         const word = model.getWordUntilPosition(position);
         const range = {
@@ -80,42 +157,143 @@ export default function SqlEditor({ value, onChange, databaseId, height }: SqlEd
           endColumn: word.endColumn,
         };
 
-        let suggestions: any[] = [
-          // SQL Keywords
-          { label: 'SELECT', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'SELECT ', range },
-          { label: 'FROM', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'FROM ', range },
-          { label: 'WHERE', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'WHERE ', range },
-          { label: 'JOIN', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'JOIN ', range },
-          { label: 'LEFT JOIN', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'LEFT JOIN ', range },
-          { label: 'INNER JOIN', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'INNER JOIN ', range },
-          { label: 'GROUP BY', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'GROUP BY ', range },
-          { label: 'ORDER BY', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'ORDER BY ', range },
-          { label: 'HAVING', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'HAVING ', range },
-          { label: 'LIMIT', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'LIMIT ', range },
-          { label: 'OFFSET', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'OFFSET ', range },
-          { label: 'AND', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'AND ', range },
-          { label: 'OR', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'OR ', range },
-          { label: 'NOT', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'NOT ', range },
-          { label: 'IN', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'IN ', range },
-          { label: 'LIKE', kind: monaco.languages.CompletionItemKind.Keyword, insertText: 'LIKE ', range },
-          { label: 'COUNT', kind: monaco.languages.CompletionItemKind.Function, insertText: 'COUNT()', range },
-          { label: 'SUM', kind: monaco.languages.CompletionItemKind.Function, insertText: 'SUM()', range },
-          { label: 'AVG', kind: monaco.languages.CompletionItemKind.Function, insertText: 'AVG()', range },
-          { label: 'MAX', kind: monaco.languages.CompletionItemKind.Function, insertText: 'MAX()', range },
-          { label: 'MIN', kind: monaco.languages.CompletionItemKind.Function, insertText: 'MIN()', range },
+        const textUntilPosition = model.getValueInRange({
+          startLineNumber: 1,
+          startColumn: 1,
+          endLineNumber: position.lineNumber,
+          endColumn: position.column,
+        });
+
+        const lineContent = model.getLineContent(position.lineNumber);
+        const textBeforeCursor = lineContent.substring(0, position.column - 1);
+
+        let suggestions: any[] = [];
+
+        // Check if we're after a dot (table.column completion)
+        const dotMatch = textBeforeCursor.match(/(\w+)\.\s*$/);
+        if (dotMatch && currentSchema) {
+          const prefix = dotMatch[1].toLowerCase();
+          const aliases = parseTableAliases(textUntilPosition);
+          const tableName = aliases.get(prefix) || prefix;
+
+          const table = currentSchema.tables.find(t => t.name.toLowerCase() === tableName);
+          if (table) {
+            // Return only columns for this table
+            return {
+              suggestions: table.columns.map(col => ({
+                label: col.name,
+                kind: monaco.languages.CompletionItemKind.Field,
+                insertText: col.name,
+                detail: `${col.type}${col.is_primary ? ' (PK)' : ''}${!col.nullable ? ' NOT NULL' : ''}`,
+                documentation: col.comment || undefined,
+                range,
+                sortText: col.is_primary ? '0' + col.name : '1' + col.name,
+              })),
+            };
+          }
+        }
+
+        // Check if we're after ON keyword (FK suggestions)
+        const onMatch = textBeforeCursor.match(/\bON\s+$/i);
+        if (onMatch && currentSchema) {
+          const tablesInQuery = findTablesInQuery(textUntilPosition, currentSchema);
+          const fkSuggestions = getFkSuggestions(tablesInQuery, currentSchema, monaco, range);
+          if (fkSuggestions.length > 0) {
+            return { suggestions: fkSuggestions };
+          }
+        }
+
+        // SQL Keywords
+        const keywords = [
+          'SELECT', 'FROM', 'WHERE', 'JOIN', 'LEFT JOIN', 'RIGHT JOIN', 'INNER JOIN',
+          'FULL OUTER JOIN', 'CROSS JOIN', 'ON', 'AND', 'OR', 'NOT', 'IN', 'LIKE',
+          'BETWEEN', 'IS NULL', 'IS NOT NULL', 'GROUP BY', 'ORDER BY', 'HAVING',
+          'LIMIT', 'OFFSET', 'UNION', 'UNION ALL', 'EXCEPT', 'INTERSECT',
+          'INSERT INTO', 'VALUES', 'UPDATE', 'SET', 'DELETE FROM',
+          'CREATE TABLE', 'ALTER TABLE', 'DROP TABLE', 'TRUNCATE',
+          'DISTINCT', 'AS', 'ASC', 'DESC', 'NULLS FIRST', 'NULLS LAST',
+          'CASE', 'WHEN', 'THEN', 'ELSE', 'END', 'COALESCE', 'NULLIF',
+          'EXISTS', 'NOT EXISTS', 'ANY', 'ALL',
         ];
 
-        // Fetch table names from database if databaseId is provided (with caching)
-        if (currentDatabaseId) {
-          const tables = await getCachedTables(currentDatabaseId);
-          const tableSuggestions = tables.map(table => ({
-            label: table,
-            kind: monaco.languages.CompletionItemKind.Class,
-            insertText: table,
-            detail: 'Table',
-            range,
-          }));
-          suggestions = [...suggestions, ...tableSuggestions];
+        suggestions = keywords.map(kw => ({
+          label: kw,
+          kind: monaco.languages.CompletionItemKind.Keyword,
+          insertText: kw + ' ',
+          range,
+          sortText: '2' + kw,
+        }));
+
+        // SQL Functions
+        const functions = [
+          { name: 'COUNT', snippet: 'COUNT($0)' },
+          { name: 'SUM', snippet: 'SUM($0)' },
+          { name: 'AVG', snippet: 'AVG($0)' },
+          { name: 'MAX', snippet: 'MAX($0)' },
+          { name: 'MIN', snippet: 'MIN($0)' },
+          { name: 'COALESCE', snippet: 'COALESCE($1, $0)' },
+          { name: 'NULLIF', snippet: 'NULLIF($1, $0)' },
+          { name: 'CAST', snippet: 'CAST($1 AS $0)' },
+          { name: 'CONCAT', snippet: 'CONCAT($0)' },
+          { name: 'SUBSTRING', snippet: 'SUBSTRING($1 FROM $2 FOR $0)' },
+          { name: 'TRIM', snippet: 'TRIM($0)' },
+          { name: 'UPPER', snippet: 'UPPER($0)' },
+          { name: 'LOWER', snippet: 'LOWER($0)' },
+          { name: 'LENGTH', snippet: 'LENGTH($0)' },
+          { name: 'NOW', snippet: 'NOW()' },
+          { name: 'CURRENT_DATE', snippet: 'CURRENT_DATE' },
+          { name: 'CURRENT_TIMESTAMP', snippet: 'CURRENT_TIMESTAMP' },
+          { name: 'DATE_TRUNC', snippet: "DATE_TRUNC('$1', $0)" },
+          { name: 'EXTRACT', snippet: 'EXTRACT($1 FROM $0)' },
+          { name: 'TO_CHAR', snippet: "TO_CHAR($1, '$0')" },
+          { name: 'TO_DATE', snippet: "TO_DATE($1, '$0')" },
+          { name: 'ARRAY_AGG', snippet: 'ARRAY_AGG($0)' },
+          { name: 'STRING_AGG', snippet: "STRING_AGG($1, '$0')" },
+          { name: 'JSON_AGG', snippet: 'JSON_AGG($0)' },
+          { name: 'ROW_NUMBER', snippet: 'ROW_NUMBER() OVER ($0)' },
+          { name: 'RANK', snippet: 'RANK() OVER ($0)' },
+          { name: 'DENSE_RANK', snippet: 'DENSE_RANK() OVER ($0)' },
+          { name: 'LAG', snippet: 'LAG($1) OVER ($0)' },
+          { name: 'LEAD', snippet: 'LEAD($1) OVER ($0)' },
+        ];
+
+        suggestions.push(...functions.map(fn => ({
+          label: fn.name,
+          kind: monaco.languages.CompletionItemKind.Function,
+          insertText: fn.snippet,
+          insertTextRules: monaco.languages.CompletionItemInsertTextRule.InsertAsSnippet,
+          detail: 'Function',
+          range,
+          sortText: '3' + fn.name,
+        })));
+
+        // Add tables and columns from schema
+        if (currentSchema) {
+          // Tables
+          for (const table of currentSchema.tables) {
+            suggestions.push({
+              label: table.name,
+              kind: monaco.languages.CompletionItemKind.Class,
+              insertText: table.name,
+              detail: `Table (${table.columns.length} columns)`,
+              documentation: table.comment || undefined,
+              range,
+              sortText: '1' + table.name,
+            });
+
+            // All columns (with table prefix for context)
+            for (const col of table.columns) {
+              suggestions.push({
+                label: `${table.name}.${col.name}`,
+                kind: monaco.languages.CompletionItemKind.Field,
+                insertText: `${table.name}.${col.name}`,
+                detail: col.type,
+                documentation: col.comment || undefined,
+                range,
+                sortText: '4' + table.name + col.name,
+              });
+            }
+          }
         }
 
         return { suggestions };