Add support for extra ORDER BY fields in RowNumber methods

- Updated RowNumber, RowNumberDesc, RowNumberPartionBy, and RowNumberDescPartionBy to accept variadic extraOrderBy parameters
- Fixed bug in RowNumberDesc that was incorrectly using ASC instead of DESC
- Enhanced rowNumber internal function to build ORDER BY clause with primary field and additional fields
- Backwards compatible - existing code continues to work without extra fields
- Added CLAUDE.md documentation for future Claude Code instances

CLAUDE.md

@@ -0,0 +1,314 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+**pgm** is a lightweight, type-safe PostgreSQL query builder for Go, built on top of jackc/pgx. It generates Go code from SQL schema files, enabling compile-time safety for database queries without the overhead of traditional ORMs.
+
+**Core Philosophy:**
+- Schema defined in SQL (not Go)
+- Minimal code generation (only table/column definitions)
+- Users provide their own models (no forced abstractions)
+- Type-safe query building with fluent API
+- Zero reflection for maximum performance
+
+## Development Commands
+
+### Building
+
+```bash
+# Build CLI with version from git tags
+make build
+
+# Build with specific version
+make build VERSION=v1.2.3
+
+# Install to GOPATH/bin
+make install
+
+# Check current version
+make version
+pgm -version
+```
+
+### Testing
+
+```bash
+# Run all tests in playground
+make test
+
+# Run benchmarks for SELECT queries
+make bench-select
+
+# Run code generator on playground schema
+make run
+```
+
+### Code Generation
+
+```bash
+# Generate Go code from SQL schema
+pgm -o ./db ./schema.sql
+
+# The generator expects a SQL schema file and outputs:
+# - One package per table in the output directory
+# - Each package contains table and column definitions
+# Example output: db/users/users.go, db/posts/posts.go
+```
+
+## Architecture
+
+### Core Components
+
+#### 1. Query Builder System (qry_*.go files)
+
+The query builder uses a **mutable, stateful design** for conditional query building:
+
+- **qry_select.go**: SELECT queries with joins, WHERE, GROUP BY, HAVING, ORDER BY, LIMIT, OFFSET
+- **qry_insert.go**: INSERT queries with RETURNING and UPSERT (ON CONFLICT) support
+- **qry_update.go**: UPDATE queries with conditional WHERE clauses
+- **qry_delete.go**: DELETE queries with WHERE conditions
+
+**Important:** Query builders accumulate state with each method call. They are designed for conditional building within a single query but should NOT be reused across multiple separate queries.
+
+```go
+// ✅ CORRECT - Conditional building
+query := users.User.Select(users.ID, users.Email)
+if nameFilter != "" {
+    query = query.Where(users.Name.Like("%" + nameFilter + "%"))
+}
+err := query.First(ctx, &id, &email)
+
+// ❌ WRONG - Reusing builder across separate queries
+baseQuery := users.User.Select(users.ID)
+baseQuery.Where(users.ID.Eq(1)).First(ctx, &id1)  // Adds ID=1
+baseQuery.Where(users.Status.Eq(2)).First(ctx, &id2)  // Has BOTH conditions!
+```
+
+Query builders are NOT thread-safe. Each goroutine must create its own query instance.
+
+#### 2. Field System (pgm_field.go)
+
+Fields are type-safe column references with:
+- Comparison operators: `Eq()`, `NotEq()`, `Gt()`, `Lt()`, `Gte()`, `Lte()`
+- Pattern matching: `Like()`, `ILike()`, `LikeFold()`, `EqFold()`
+- NULL checks: `IsNull()`, `IsNotNull()`
+- Array operations: `Any()`, `NotAny()`
+- Aggregate functions: `Count()`, `Sum()`, `Avg()`, `Min()`, `Max()`
+- String functions: `Lower()`, `Upper()`, `Trim()`, `StringEscape()`
+- Special functions: `ConcatWs()`, `StringAgg()`, `DateTrunc()`, `RowNumber()`
+
+**Security:** Functions like `ConcatWs()`, `StringAgg()`, and `DateTrunc()` validate inputs and escape SQL strings. They use allowlists for parameters like date truncation levels.
+
+#### 3. Connection Pool (pgm.go)
+
+Global connection pool using pgxpool with atomic pointer for thread safety:
+
+- `InitPool(Config)`: Initialize once at startup (panics if called multiple times or with invalid config)
+- `GetPool()`: Retrieve pool instance (panics if not initialized)
+- `ClosePool()`: Graceful shutdown
+- `BeginTx(ctx)`: Start transactions
+
+The pool is stored in an `atomic.Pointer[pgxpool.Pool]` for lock-free concurrent access.
+
+#### 4. Code Generator (cmd/)
+
+Parses SQL schema files and generates Go code:
+
+- **cmd/main.go**: CLI entry point with version flag support
+- **cmd/parse.go**: Regex-based SQL parser (has known limitations)
+- **cmd/generate.go**: Code generation with go/format for proper formatting
+- **cmd/version.go**: Version string generation from build-time ldflags
+
+**Parser Limitations:**
+- No multi-line comments (`/* */`)
+- Limited support for complex data types (arrays, JSON, JSONB)
+- No advanced PostgreSQL features (PARTITION BY, INHERITS)
+- Some constraints (CHECK, EXCLUDE) not parsed
+
+Generated files include a header comment with version and timestamp:
+```go
+// Code generated by code.patial.tech/go/pgm/cmd v1.2.3 on 2025-11-16 04:05:43 DO NOT EDIT.
+```
+
+#### 5. Table System (pgm_table.go)
+
+Minimal table metadata:
+```go
+type Table struct {
+    Name         string    // Table name
+    FieldCount   int       // Number of columns
+    PK           []string  // Primary key columns
+    DerivedTable Query     // For subqueries/CTEs
+}
+```
+
+Provides factory methods: `Select()`, `Insert()`, `Update()`, `Delete()`
+
+### String Builder Pool
+
+Uses `sync.Pool` for efficient string building (qry.go):
+```go
+var sbPool = sync.Pool{
+    New: func() any { return new(strings.Builder) }
+}
+```
+
+All query builders use `getSB()` / `putSB()` to reduce allocations.
+
+### Error Handling
+
+Custom errors in pgm.go:
+- `ErrConnStringMissing`: Connection string validation
+- `ErrInitTX`: Transaction initialization failure  
+- `ErrCommitTX`: Transaction commit failure
+- `ErrNoRows`: Wrapper for pgx.ErrNoRows
+
+Use `pgm.IsNotFound(err)` to check for no rows errors.
+
+### Generated Code Structure
+
+For a schema with `users` and `posts` tables:
+```
+db/
+├── schema.go              # Table definitions and DerivedTable helper
+├── user/
+│   └── users.go           # User table columns as constants
+├── post/
+│   └── posts.go           # Post table columns as constants
+└── ...
+```
+
+Each table file exports constants like:
+```go
+const (
+    All   pgm.Field = "users.*"
+    ID    pgm.Field = "users.id"
+    Email pgm.Field = "users.email"
+    // ... all columns
+)
+```
+
+### Naming Conventions
+
+- **Table pluralization**: `pluralToSingular()` in cmd/generate.go handles irregular plurals (people→person, children→child) and common patterns (-ies→-y, -ves→-fe, -es→-e, -s→"")
+- **Field naming**: Snake_case columns converted to PascalCase (first_name → FirstName)
+- **ID suffix**: Fields ending in `_id` become `ID` not `Id` (user_id → UserID)
+
+## Key Implementation Details
+
+### Query Building Strategy
+
+1. **Pre-allocation**: Queries estimate final string length via `averageLen()` methods to reduce allocations
+2. **Conditional accumulation**: All clauses stored in slices, built on demand
+3. **Parameterized queries**: Uses PostgreSQL numbered parameters (`$1`, `$2`, etc.)
+4. **Builder methods return interfaces**: Enforces correct method call sequences at compile time
+
+Example type progression:
+```go
+SelectClause → WhereClause → AfterWhere → OrderByClause → Query → First/All
+```
+
+### Transaction Handling
+
+Pattern used throughout:
+```go
+tx, err := pgm.BeginTx(ctx)
+if err != nil { return err }
+defer tx.Rollback(ctx)  // Safe to call after commit
+
+// ... operations using ExecTx, FirstTx, AllTx methods ...
+
+return tx.Commit(ctx)
+```
+
+All query execution methods have `Tx` variants that accept `pgx.Tx`.
+
+### Full-Text Search Helpers
+
+Helper functions for PostgreSQL tsvector queries:
+- `TsAndQuery()`: AND operator between terms
+- `TsPrefixAndQuery()`: AND with prefix matching `:*`
+- `TsOrQuery()`: OR operator
+- `TsPrefixOrQuery()`: OR with prefix matching
+
+Used with tsvector columns via `Field.TsQuery()`.
+
+## Testing
+
+Tests are in the `playground/` directory:
+- **playground/schema.sql**: Test database schema
+- **playground/db/**: Generated code from schema
+- **playground/*_test.go**: Integration tests for SELECT, INSERT, UPDATE, DELETE
+- **playground/local_select_test.go**: Additional SELECT test cases
+
+Tests require a running PostgreSQL instance. The playground uses the generated code to verify the query builder works correctly.
+
+## Version Management
+
+Version is injected at build time via ldflags:
+```bash
+go build -ldflags "-X main.version=v1.2.3" ./cmd
+```
+
+The Makefile automatically extracts version from git tags:
+```makefile
+VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
+```
+
+This version appears in:
+- CLI `pgm -version` output
+- Generated file headers
+- Version string formatting in cmd/version.go
+
+## Common Patterns
+
+### Connection Pool Initialization
+Always initialize once at startup and defer cleanup:
+```go
+func main() {
+    pgm.InitPool(pgm.Config{
+        ConnString: os.Getenv("DATABASE_URL"),
+        MaxConns:   25,
+        MinConns:   5,
+    })
+    defer pgm.ClosePool()
+    // ...
+}
+```
+
+### Safe Query Execution
+Check for no rows using the helper:
+```go
+err := users.User.Select(users.Email).Where(users.ID.Eq(id)).First(ctx, &email)
+if pgm.IsNotFound(err) {
+    // Handle not found case
+}
+if err != nil {
+    // Handle other errors
+}
+```
+
+### Validation Requirements
+- UPDATE requires at least one `Set()` call
+- INSERT requires at least one `Set()` call  
+- DELETE without `Where()` deletes ALL rows (dangerous!)
+
+All execution methods validate these requirements and return descriptive errors.
+
+## Performance Considerations
+
+- **sync.Pool**: Reuses string builders across queries
+- **Pre-allocation**: Queries pre-calculate buffer sizes
+- **Zero reflection**: Direct field access, no runtime type inspection
+- **pgxpool**: Leverages jackc/pgx's efficient connection pooling
+- **Direct scanning**: Users scan into their own types, no intermediate mapping
+
+## Security Notes
+
+- All queries use parameterized statements (PostgreSQL numbered parameters)
+- Field validation in functions like `DateTrunc()` uses allowlists
+- SQL string escaping in `escapeSQLString()` for literal values
+- Identifier validation via regex in `validateSQLIdentifier()`
+- Connection pool configuration validates against negative values and invalid ranges

pgm_field.go

@@ -152,24 +152,24 @@ func (f Field) Desc() Field {
 	return Field(f.String() + " DESC")
 }
 
-func (f Field) RowNumber(as string) Field {
-	return rowNumber(&f, nil, true, as)
+func (f Field) RowNumber(as string, extraOrderBy ...Field) Field {
+	return rowNumber(&f, nil, true, as, extraOrderBy...)
 }
 
-func (f Field) RowNumberDesc(as string) Field {
-	return rowNumber(&f, nil, true, as)
+func (f Field) RowNumberDesc(as string, extraOrderBy ...Field) Field {
+	return rowNumber(&f, nil, false, as, extraOrderBy...)
 }
 
 // RowNumberPartionBy in ascending order
-func (f Field) RowNumberPartionBy(partition Field, as string) Field {
-	return rowNumber(&f, &partition, true, as)
+func (f Field) RowNumberPartionBy(partition Field, as string, extraOrderBy ...Field) Field {
+	return rowNumber(&f, &partition, true, as, extraOrderBy...)
 }
 
-func (f Field) RowNumberDescPartionBy(partition Field, as string) Field {
-	return rowNumber(&f, &partition, false, as)
+func (f Field) RowNumberDescPartionBy(partition Field, as string, extraOrderBy ...Field) Field {
+	return rowNumber(&f, &partition, false, as, extraOrderBy...)
 }
 
-func rowNumber(f, partition *Field, isAsc bool, as string) Field {
+func rowNumber(f, partition *Field, isAsc bool, as string, extraOrderBy ...Field) Field {
 	// Validate as parameter is a valid SQL identifier
 	if as != "" {
 		if err := validateSQLIdentifier(as); err != nil {
@@ -188,11 +188,27 @@ func rowNumber(f, partition *Field, isAsc bool, as string) Field {
 	}
 
 	col := f.String()
-	if partition != nil {
-		return Field("ROW_NUMBER() OVER (PARTITION BY " + partition.String() + " ORDER BY " + col + orderBy + ") AS " + as)
+
+	// Build ORDER BY clause with primary field and extra fields
+	sb := getSB()
+	defer putSB(sb)
+
+	sb.WriteString(col)
+	sb.WriteString(orderBy)
+
+	// Add extra ORDER BY fields
+	for _, extra := range extraOrderBy {
+		sb.WriteString(", ")
+		sb.WriteString(extra.String())
 	}
 
-	return Field("ROW_NUMBER() OVER (ORDER BY " + col + orderBy + ") AS " + as)
+	orderByClause := sb.String()
+
+	if partition != nil {
+		return Field("ROW_NUMBER() OVER (PARTITION BY " + partition.String() + " ORDER BY " + orderByClause + ") AS " + as)
+	}
+
+	return Field("ROW_NUMBER() OVER (ORDER BY " + orderByClause + ") AS " + as)
 }
 
 func (f Field) IsNull() Conditioner {