diff --git a/executor/src/lib.rs b/executor/src/lib.rs
index abc11aa..2f655be 100644
--- a/executor/src/lib.rs
+++ b/executor/src/lib.rs
@@ -2816,6 +2816,83 @@ mod tests {
         assert!(!rows.iter().any(|r| *r.fields[0].deref() == Value::Int32(2)));
     }
 
+    #[test]
+    fn test_update_primary_key_column_fails() {
+        let (executor, _temp_dir) = create_test_executor();
+
+        // Create and populate table
+        execute_single(
+            &executor,
+            "CREATE TABLE users (id INT32 PRIMARY_KEY, name STRING, age INT32);",
+        );
+        execute_single(
+            &executor,
+            "INSERT INTO users (id, name, age) VALUES (1, 'Alice', 25);",
+        );
+        execute_single(
+            &executor,
+            "INSERT INTO users (id, name, age) VALUES (2, 'Bob', 30);",
+        );
+
+        // Try to update primary key column
+        let result = execute_single(&executor, "UPDATE users SET id = 999 WHERE id = 1;");
+
+        assert_parse_error_contains(result, "primary key column 'id' cannot be updated");
+
+        // Verify no records were updated
+        let (select_plan, select_ast) =
+            create_single_statement("SELECT id, name, age FROM users;", &executor);
+        let result = executor.execute_statement(&select_plan, &select_ast);
+
+        let (_, rows) = expect_select_successful(result);
+        assert_eq!(rows.len(), 2);
+
+        // Alice should still have id = 1
+        let alice = rows
+            .iter()
+            .find(|r| *r.fields[0].deref() == Value::Int32(1))
+            .unwrap();
+        assert_eq!(*alice.fields[1].deref(), Value::String("Alice".into()));
+        assert_eq!(*alice.fields[2].deref(), Value::Int32(25));
+    }
+
+    #[test]
+    fn test_update_multiple_columns_including_primary_key_fails() {
+        let (executor, _temp_dir) = create_test_executor();
+
+        // Create and populate table
+        execute_single(
+            &executor,
+            "CREATE TABLE users (id INT32 PRIMARY_KEY, name STRING, age INT32);",
+        );
+        execute_single(
+            &executor,
+            "INSERT INTO users (id, name, age) VALUES (1, 'Alice', 25);",
+        );
+
+        // Try to update both primary key and other columns
+        let result = execute_single(
+            &executor,
+            "UPDATE users SET id = 999, name = 'Alicia', age = 26 WHERE id = 1;",
+        );
+
+        assert_parse_error_contains(result, "primary key column 'id' cannot be updated");
+
+        // Verify no records were updated
+        let (select_plan, select_ast) =
+            create_single_statement("SELECT id, name, age FROM users;", &executor);
+        let result = executor.execute_statement(&select_plan, &select_ast);
+
+        let (_, rows) = expect_select_successful(result);
+        assert_eq!(rows.len(), 1);
+
+        // Alice should remain unchanged
+        let alice = &rows[0];
+        assert_eq!(*alice.fields[0].deref(), Value::Int32(1));
+        assert_eq!(*alice.fields[1].deref(), Value::String("Alice".into()));
+        assert_eq!(*alice.fields[2].deref(), Value::Int32(25));
+    }
+
     #[test]
     fn test_drop_table_empty_table() {
         let (executor, _temp_dir) = create_test_executor();
diff --git a/executor/src/statement_executor.rs b/executor/src/statement_executor.rs
index c0bf856..97c60c6 100644
--- a/executor/src/statement_executor.rs
+++ b/executor/src/statement_executor.rs
@@ -519,6 +519,7 @@ impl<'e, 'q> StatementExecutor<'e, 'q> {
                         Ok(cm) => cm,
                         Err(e) => return StatementResult::from(&e),
                     };
+
                 let e = ExpressionExecutor::with_single_record(&record_handle.record, self.ast);
                 match e.execute_expression(*expression) {
                     Ok(value) => {
diff --git a/planner/src/analyzer.rs b/planner/src/analyzer.rs
index 55741a2..613ae07 100644
--- a/planner/src/analyzer.rs
+++ b/planner/src/analyzer.rs
@@ -65,6 +65,8 @@ pub enum AnalyzerError {
     ColumnAlreadyExists { column: String },
     #[error("column '{column}' cannot be dropped")]
     ColumnCannotBeDropped { column: String },
+    #[error("primary key column '{column}' cannot be updated")]
+    PrimaryKeyCannotBeUpdated { column: String },
     #[error("primary key missing in create table statement")]
     PrimaryKeyMissing,
     #[error("unexpected type: expected {expected}, got {got}")]
@@ -366,6 +368,17 @@ impl<'a> Analyzer<'a> {
             .collect::<Result<Vec<_>, AnalyzerError>>()?;
         let (resolved_columns, resolved_values): (Vec<_>, Vec<_>) =
             resolved_column_setters.into_iter().unzip();
+
+        // Check if any column being updated is the primary key
+        for &column in &resolved_columns {
+            let column_name = self.get_column_name(column)?;
+            if column_name == primary_key {
+                return Err(AnalyzerError::PrimaryKeyCannotBeUpdated {
+                    column: column_name,
+                });
+            }
+        }
+
         let resolved_where_clause = update
             .where_clause
             .map(|node_id| self.resolve_expression(node_id))
@@ -3163,6 +3176,112 @@ mod tests {
         }
     }
 
+    #[test]
+    fn analyze_update_primary_key_errors() {
+        let catalog = catalog_with_users();
+        let mut ast = Ast::default();
+
+        // table identifier
+        let table_ident = ast.add_node(Expression::Identifier(IdentifierNode {
+            value: "users".into(),
+        }));
+        let table_name = ast.add_node(Expression::TableIdentifier(TableIdentifierNode {
+            identifier: table_ident,
+            alias: None,
+        }));
+
+        // column (id - primary key)
+        let id_ident = ast.add_node(Expression::Identifier(IdentifierNode {
+            value: "id".into(),
+        }));
+        let col_id = ast.add_node(Expression::ColumnIdentifier(ColumnIdentifierNode {
+            identifier: id_ident,
+            table_alias: None,
+        }));
+
+        // value
+        let val_new = ast.add_node(Expression::Literal(LiteralNode {
+            value: Literal::Int(999),
+        }));
+
+        let update = UpdateStatement {
+            table_name,
+            column_setters: vec![(col_id, val_new)],
+            where_clause: None,
+        };
+        ast.add_statement(Statement::Update(update));
+
+        let analyzer = Analyzer::new(&ast, catalog);
+        let errs = analyzer.analyze().unwrap_err();
+        assert_eq!(errs.len(), 1);
+        let err = &errs[0];
+        match err {
+            AnalyzerError::PrimaryKeyCannotBeUpdated { column } => {
+                assert_eq!(column, "id");
+            }
+            other => panic!("expected PrimaryKeyCannotBeUpdated, got: {:?}", other),
+        }
+    }
+
+    #[test]
+    fn analyze_update_multiple_columns_including_primary_key_errors() {
+        let catalog = catalog_with_users();
+        let mut ast = Ast::default();
+
+        // table identifier
+        let table_ident = ast.add_node(Expression::Identifier(IdentifierNode {
+            value: "users".into(),
+        }));
+        let table_name = ast.add_node(Expression::TableIdentifier(TableIdentifierNode {
+            identifier: table_ident,
+            alias: None,
+        }));
+
+        // column name (non-primary key)
+        let name_ident = ast.add_node(Expression::Identifier(IdentifierNode {
+            value: "name".into(),
+        }));
+        let col_name = ast.add_node(Expression::ColumnIdentifier(ColumnIdentifierNode {
+            identifier: name_ident,
+            table_alias: None,
+        }));
+
+        // column id (primary key)
+        let id_ident = ast.add_node(Expression::Identifier(IdentifierNode {
+            value: "id".into(),
+        }));
+        let col_id = ast.add_node(Expression::ColumnIdentifier(ColumnIdentifierNode {
+            identifier: id_ident,
+            table_alias: None,
+        }));
+
+        // values
+        let val_name = ast.add_node(Expression::Literal(LiteralNode {
+            value: Literal::String("John".into()),
+        }));
+        let val_id = ast.add_node(Expression::Literal(LiteralNode {
+            value: Literal::Int(999),
+        }));
+
+        let update = UpdateStatement {
+            table_name,
+            column_setters: vec![(col_name, val_name), (col_id, val_id)],
+            where_clause: None,
+        };
+        ast.add_statement(Statement::Update(update));
+
+        let analyzer = Analyzer::new(&ast, catalog);
+        let errs = analyzer.analyze().unwrap_err();
+        assert_eq!(errs.len(), 1);
+        let err = &errs[0];
+        match err {
+            AnalyzerError::PrimaryKeyCannotBeUpdated { column } => {
+                assert_eq!(column, "id");
+            }
+            other => panic!("expected PrimaryKeyCannotBeUpdated, got: {:?}", other),
+        }
+    }
+
     #[test]
     fn analyze_delete_with_where_clause() {
         let catalog = catalog_with_users();