feat!: remove automatic PRIMARY KEY AUTO_INCREMENT on first column

The first column no longer implicitly receives PRIMARY KEY AUTO_INCREMENT.
Define primary keys explicitly via table_constraints<T> or column attributes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Pierre-Luc Gagné

CHANGELOG.md

@@ -8,6 +8,10 @@ Versioning follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+### Removed
+
+- `table_inline_primary_key<T>` trait and automatic `PRIMARY KEY AUTO_INCREMENT` on the first column — define primary keys explicitly via `table_constraints<T>` or column attributes (`column_attr::auto_increment`)
+
 ---
 
 ## [4.4.1] – 2026-03-29

examples/tables_with_constraints.cpp

@@ -1,10 +1,9 @@
 // tables_with_constraints.cpp — DSMySQL table constraints example.
 //
 // Demonstrates how to:
-//  1. Define table-level PRIMARY KEY, secondary indexes, and other constraints
+//  1. Define table-level constraints and secondary indexes
 //  2. Customize CREATE TABLE output with table_constraints<T> trait
-//  3. Disable inline implicit primary key with table_inline_primary_key<T>
-//  4. Use table_constraint helpers: primary_key, key, unique_key, check, etc.
+//  3. Use table_constraint helpers: primary_key, key, unique_key, check, etc.
 //
 // Build with:
 //   cmake --preset release && cmake --build build -j$(nproc)
@@ -45,23 +44,14 @@ struct order_detail {
 };
 
 // ===================================================================
-// Customize symbol table: define table-level PRIMARY KEY and secondary
-// indexes using the table_constraints<T> trait.
+// Customize symbol table: define secondary indexes using the
+// table_constraints<T> trait.
 // ===================================================================
 
-template <>
-struct ds_mysql::table_inline_primary_key<symbol> {
-    // Disable the default inline PRIMARY KEY AUTO_INCREMENT on first column
-    static constexpr bool value = false;
-};
-
 template <>
 struct ds_mysql::table_constraints<symbol> {
     static std::vector<std::string> get() {
         return {
-            // Define table-level PRIMARY KEY(id)
-            ds_mysql::table_constraint::primary_key<symbol::id>(),
-
             // Define secondary index on exchange_id
             ds_mysql::table_constraint::key<symbol::exchange_id>(ds_mysql::index_id<"index_exchange_id">{}),
 
@@ -75,18 +65,10 @@ struct ds_mysql::table_constraints<symbol> {
 // Customize order_detail table: define UNIQUE constraint and CHECK constraint
 // ===================================================================
 
-template <>
-struct ds_mysql::table_inline_primary_key<order_detail> {
-    static constexpr bool value = false;
-};
-
 template <>
 struct ds_mysql::table_constraints<order_detail> {
     static std::vector<std::string> get() {
         return {
-            // Define table-level PRIMARY KEY(id)
-            ds_mysql::table_constraint::primary_key<order_detail::id>(),
-
             // Define unique constraint on (order_id, line_number)
             ds_mysql::table_constraint::unique_key<order_detail::order_id, order_detail::line_number>(
                 ds_mysql::index_id<"uq_order_line">{}),

lib/include/ds_mysql/schema_generator.hpp

@@ -469,9 +469,6 @@ template <typename T, std::size_t I>
     if constexpr (!is_optional_v<field_type>) {
         col += " NOT NULL";
     }
-    if constexpr (I == 0) {
-        col += " PRIMARY KEY AUTO_INCREMENT";
-    }
     return col;
 }
 

lib/include/ds_mysql/sql_ddl.hpp

@@ -75,21 +75,11 @@ enum class Encryption {
 // ===================================================================
 // CREATE TABLE constraint customization
 //
-// table_inline_primary_key<T>
-//   - true  (default): first column is emitted as `PRIMARY KEY AUTO_INCREMENT`
-//   - false          : first column is emitted as `AUTO_INCREMENT` only,
-//                      allowing table_constraints<T> to define table-level PK
-//
 // table_constraints<T>
 //   - return additional table-level constraints/index definitions appended
 //     inside CREATE TABLE (...)
 // ===================================================================
 
-template <typename T>
-struct table_inline_primary_key {
-    static constexpr bool value = true;
-};
-
 template <typename T>
 struct table_constraints {
     [[nodiscard]] static std::vector<std::string> get() {
@@ -1034,12 +1024,6 @@ template <typename T, std::size_t I>
     if constexpr (!is_field_nullable_v<field_type>) {
         col += " NOT NULL";
     }
-    if constexpr (I == 0) {
-        if constexpr (table_inline_primary_key<T>::value) {
-            col += " PRIMARY KEY AUTO_INCREMENT";
-        }
-        // When inline PK is disabled, typed column attributes should handle AUTO_INCREMENT
-    }
     if constexpr (requires { field_type::ddl_auto_increment; } && field_type::ddl_auto_increment) {
         col += " AUTO_INCREMENT";
     }