perf enhancement

README.md

@@ -172,6 +172,56 @@ func main() {
 }
 ```
 
+## Important: Query Builder Lifecycle
+
+⚠️ **Query builders are single-use and should not be reused:**
+
+```go
+// ❌ WRONG - Don't reuse query builders
+baseQuery := users.User.Select(users.ID, users.Email)
+baseQuery.Where(users.ID.Eq(1)).First(ctx, &id1, &email1)
+baseQuery.Where(users.Status.Eq(2)).First(ctx, &id2, &email2)
+// Second query has BOTH WHERE clauses - incorrect behavior!
+
+// ✅ CORRECT - Create new query each time
+users.User.Select(users.ID, users.Email).Where(users.ID.Eq(1)).First(ctx, &id1, &email1)
+users.User.Select(users.ID, users.Email).Where(users.Status.Eq(2)).First(ctx, &id2, &email2)
+```
+
+**Why?** Query builders are mutable and accumulate state. Each method call modifies the builder, so reusing the same builder causes conditions to stack up.
+
+### Thread Safety
+
+⚠️ **Query builders are NOT thread-safe** and must not be shared across goroutines:
+
+```go
+// ✅ CORRECT - Each goroutine creates its own query
+for i := 0; i < 10; i++ {
+    go func(id int) {
+        var email string
+        err := users.User.Select(users.Email).
+            Where(users.ID.Eq(id)).
+            First(ctx, &email)
+        // Process result...
+    }(i)
+}
+
+// ❌ WRONG - Sharing query builder across goroutines
+baseQuery := users.User.Select(users.Email)
+for i := 0; i < 10; i++ {
+    go func(id int) {
+        var email string
+        baseQuery.Where(users.ID.Eq(id)).First(ctx, &email)
+        // RACE CONDITION! Multiple goroutines modifying shared state
+    }(i)
+}
+```
+
+**Thread-Safe Components:**
+- ✅ Connection Pool - Safe for concurrent use
+- ✅ Table objects - Safe to share
+- ❌ Query builders - Create new instance per goroutine
+
 ## Usage Examples
 
 ### SELECT Queries

pgm.go

@@ -25,13 +25,15 @@ var (
 	ErrConnStringMissing = errors.New("connection string is empty")
 )
 
-// Errors
+// Common errors returned by pgm operations
 var (
 	ErrInitTX   = errors.New("failed to init db.tx")
 	ErrCommitTX = errors.New("failed to commit db.tx")
 	ErrNoRows   = errors.New("no data found")
 )
 
+// Config holds the configuration for initializing the connection pool.
+// All fields except ConnString are optional and will use pgx defaults if not set.
 type Config struct {
 	ConnString      string
 	MaxConns        int32
@@ -40,7 +42,17 @@ type Config struct {
 	MaxConnIdleTime time.Duration
 }
 
-// InitPool will create new pgxpool.Pool and will keep it for its working
+// InitPool initializes the connection pool with the provided configuration.
+// It validates the configuration and panics if invalid.
+// This function should be called once at application startup.
+//
+// Example:
+//
+//	pgm.InitPool(pgm.Config{
+//	    ConnString: "postgres://user:pass@localhost/dbname",
+//	    MaxConns:   100,
+//	    MinConns:   5,
+//	})
 func InitPool(conf Config) {
 	if conf.ConnString == "" {
 		panic(ErrConnStringMissing)
@@ -88,9 +100,15 @@ func InitPool(conf Config) {
 	poolPGX.Store(p)
 }
 
-// GetPool instance
+// GetPool returns the initialized connection pool instance.
+// It panics with a descriptive message if InitPool() has not been called.
+// This is a fail-fast approach to catch programming errors early.
 func GetPool() *pgxpool.Pool {
-	return poolPGX.Load()
+	p := poolPGX.Load()
+	if p == nil {
+		panic("pgm: connection pool not initialized, call InitPool() first")
+	}
+	return p
 }
 
 // ClosePool closes the connection pool gracefully.
@@ -102,7 +120,21 @@ func ClosePool() {
 	}
 }
 
-// BeginTx begins a pgx poll transaction
+// BeginTx begins a new database transaction from the connection pool.
+// Returns an error if the transaction cannot be started.
+// Remember to commit or rollback the transaction when done.
+//
+// Example:
+//
+//	tx, err := pgm.BeginTx(ctx)
+//	if err != nil {
+//	    return err
+//	}
+//	defer tx.Rollback(ctx) // rollback on error
+//
+//	// ... do work ...
+//
+//	return tx.Commit(ctx)
 func BeginTx(ctx context.Context) (pgx.Tx, error) {
 	tx, err := poolPGX.Load().Begin(ctx)
 	if err != nil {
@@ -113,32 +145,43 @@ func BeginTx(ctx context.Context) (pgx.Tx, error) {
 	return tx, nil
 }
 
-// IsNotFound error check
+// IsNotFound checks if an error is a "no rows" error from pgx.
+// Returns true if the error indicates no rows were found in a query result.
 func IsNotFound(err error) bool {
 	return errors.Is(err, pgx.ErrNoRows)
 }
 
-// PgTime as in UTC
+// PgTime converts a Go time.Time to PostgreSQL timestamptz type.
+// The time is stored as-is (preserves timezone information).
 func PgTime(t time.Time) pgtype.Timestamptz {
 	return pgtype.Timestamptz{Time: t, Valid: true}
 }
 
+// PgTimeNow returns the current time as PostgreSQL timestamptz type.
 func PgTimeNow() pgtype.Timestamptz {
 	return pgtype.Timestamptz{Time: time.Now(), Valid: true}
 }
 
+// TsAndQuery converts a text search query to use AND operator between terms.
+// Example: "hello world" becomes "hello & world"
 func TsAndQuery(q string) string {
 	return strings.Join(strings.Fields(q), " & ")
 }
 
+// TsPrefixAndQuery converts a text search query to use AND operator with prefix matching.
+// Example: "hello world" becomes "hello:* & world:*"
 func TsPrefixAndQuery(q string) string {
 	return strings.Join(fieldsWithSufix(q, ":*"), " & ")
 }
 
+// TsOrQuery converts a text search query to use OR operator between terms.
+// Example: "hello world" becomes "hello | world"
 func TsOrQuery(q string) string {
 	return strings.Join(strings.Fields(q), " | ")
 }
 
+// TsPrefixOrQuery converts a text search query to use OR operator with prefix matching.
+// Example: "hello world" becomes "hello:* | world:*"
 func TsPrefixOrQuery(q string) string {
 	return strings.Join(fieldsWithSufix(q, ":*"), " | ")
 }

pgm_field.go

@@ -45,7 +45,12 @@ func escapeSQLString(s string) string {
 }
 
 func (f Field) Name() string {
-	return strings.Split(string(f), ".")[1]
+	s := string(f)
+	idx := strings.LastIndexByte(s, '.')
+	if idx == -1 {
+		return s // Return as-is if no dot
+	}
+	return s[idx+1:] // Return part after last dot
 }
 
 func (f Field) String() string {
@@ -66,19 +71,19 @@ func ConcatWs(sep string, fields ...Field) Field {
 }
 
 // StringAgg creates a STRING_AGG SQL function.
-// SECURITY: The exp parameter must be a valid field/column name, not arbitrary SQL.
+// SECURITY: The field parameter provides type safety by accepting only Field type.
 // The sep parameter should only be a constant string. Single quotes will be escaped.
-func StringAgg(exp, sep string) Field {
+func StringAgg(field Field, sep string) Field {
 	escapedSep := escapeSQLString(sep)
-	return Field("string_agg(" + exp + ",'" + escapedSep + "')")
+	return Field("string_agg(" + field.String() + ",'" + escapedSep + "')")
 }
 
 // StringAggCast creates a STRING_AGG SQL function with cast to varchar.
-// SECURITY: The exp parameter must be a valid field/column name, not arbitrary SQL.
+// SECURITY: The field parameter provides type safety by accepting only Field type.
 // The sep parameter should only be a constant string. Single quotes will be escaped.
-func StringAggCast(exp, sep string) Field {
+func StringAggCast(field Field, sep string) Field {
 	escapedSep := escapeSQLString(sep)
-	return Field("string_agg(cast(" + exp + " as varchar),'" + escapedSep + "')")
+	return Field("string_agg(cast(" + field.String() + " as varchar),'" + escapedSep + "')")
 }
 
 // StringEscape will wrap field with:

pgm_field_test.go

@@ -102,29 +102,29 @@ func TestConcatWsSQLInjectionPrevention(t *testing.T) {
 func TestStringAggSQLInjectionPrevention(t *testing.T) {
 	tests := []struct {
 		name     string
-		exp      string
+		field    Field
 		sep      string
 		contains string
 	}{
 		{
 			name:     "safe parameters",
-			exp:      "column_name",
+			field:    Field("column_name"),
 			sep:      ", ",
 			contains: "string_agg(column_name,', ')",
 		},
 		{
 			name:     "escaped quotes in separator",
 			sep:      "'; DROP TABLE users; --",
-			exp:      "col",
+			field:    Field("col"),
 			contains: "string_agg(col,'''; DROP TABLE users; --')",
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			result := StringAgg(tt.exp, tt.sep)
+			result := StringAgg(tt.field, tt.sep)
 			if !strings.Contains(string(result), tt.contains) {
-				t.Errorf("StringAgg(%q, %q) = %q, should contain %q", tt.exp, tt.sep, result, tt.contains)
+				t.Errorf("StringAgg(%v, %q) = %q, should contain %q", tt.field, tt.sep, result, tt.contains)
 			}
 		})
 	}
@@ -132,7 +132,7 @@ func TestStringAggSQLInjectionPrevention(t *testing.T) {
 
 // TestStringAggCastSQLInjectionPrevention tests that StringAggCast escapes quotes
 func TestStringAggCastSQLInjectionPrevention(t *testing.T) {
-	result := StringAggCast("column", "'; DROP TABLE")
+	result := StringAggCast(Field("column"), "'; DROP TABLE")
 	expected := "string_agg(cast(column as varchar),'''; DROP TABLE')"
 	if string(result) != expected {
 		t.Errorf("StringAggCast should escape quotes, got %q, want %q", result, expected)
@@ -336,3 +336,47 @@ func TestSQLInjectionAttackVectors(t *testing.T) {
 		}
 	})
 }
+
+// TestFieldName tests Field.Name() method
+func TestFieldName(t *testing.T) {
+	tests := []struct {
+		name     string
+		field    Field
+		expected string
+	}{
+		{
+			name:     "field with table prefix",
+			field:    Field("users.email"),
+			expected: "email",
+		},
+		{
+			name:     "field with schema and table prefix",
+			field:    Field("public.users.email"),
+			expected: "email",
+		},
+		{
+			name:     "field without dot",
+			field:    Field("email"),
+			expected: "email",
+		},
+		{
+			name:     "field with multiple dots",
+			field:    Field("schema.table.column"),
+			expected: "column",
+		},
+		{
+			name:     "aggregate function",
+			field:    Field("COUNT(users.id)"),
+			expected: "id)",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := tt.field.Name()
+			if result != tt.expected {
+				t.Errorf("Field.Name() = %q, want %q", result, tt.expected)
+			}
+		})
+	}
+}

pgm_test.go

@@ -0,0 +1,706 @@
+// Patial Tech.
+// Author, Ankit Patial
+
+package pgm
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/jackc/pgx/v5"
+)
+
+// TestGetPoolNotInitialized verifies that GetPool panics when pool is not initialized
+func TestGetPoolNotInitialized(t *testing.T) {
+	// Save current pool state
+	currentPool := poolPGX.Load()
+
+	// Clear the pool to simulate uninitialized state
+	poolPGX.Store(nil)
+
+	// Restore pool after test
+	defer func() {
+		poolPGX.Store(currentPool)
+	}()
+
+	// Verify panic occurs
+	defer func() {
+		if r := recover(); r == nil {
+			t.Error("GetPool should panic when pool not initialized")
+		} else {
+			// Check panic message
+			msg, ok := r.(string)
+			if !ok || !strings.Contains(msg, "not initialized") {
+				t.Errorf("Expected panic message about initialization, got: %v", r)
+			}
+		}
+	}()
+
+	GetPool() // Should panic
+}
+
+// TestConfigValidation tests that InitPool validates configuration
+func TestConfigValidation(t *testing.T) {
+	tests := []struct {
+		name      string
+		config    Config
+		wantPanic bool
+		panicMsg  string
+	}{
+		{
+			name: "empty connection string",
+			config: Config{
+				ConnString: "",
+			},
+			wantPanic: true,
+			panicMsg:  "connection string is empty",
+		},
+		{
+			name: "MinConns greater than MaxConns",
+			config: Config{
+				ConnString: "postgres://localhost/test",
+				MaxConns:   5,
+				MinConns:   10,
+			},
+			wantPanic: true,
+			panicMsg:  "MinConns",
+		},
+		{
+			name: "negative MaxConns",
+			config: Config{
+				ConnString: "postgres://localhost/test",
+				MaxConns:   -1,
+			},
+			wantPanic: true,
+			panicMsg:  "negative",
+		},
+		{
+			name: "negative MinConns",
+			config: Config{
+				ConnString: "postgres://localhost/test",
+				MinConns:   -1,
+			},
+			wantPanic: true,
+			panicMsg:  "negative",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			defer func() {
+				r := recover()
+				if tt.wantPanic && r == nil {
+					t.Errorf("InitPool should panic for %s", tt.name)
+				}
+				if !tt.wantPanic && r != nil {
+					t.Errorf("InitPool should not panic for %s, got: %v", tt.name, r)
+				}
+				if tt.wantPanic && r != nil {
+					msg := ""
+					switch v := r.(type) {
+					case string:
+						msg = v
+					case error:
+						msg = v.Error()
+					}
+					if !strings.Contains(msg, tt.panicMsg) {
+						t.Errorf("Expected panic message to contain %q, got: %q", tt.panicMsg, msg)
+					}
+				}
+			}()
+
+			InitPool(tt.config)
+		})
+	}
+}
+
+// TestClosePoolIdempotent verifies ClosePool can be called multiple times safely
+func TestClosePoolIdempotent(t *testing.T) {
+	// Save current pool
+	currentPool := poolPGX.Load()
+	defer func() {
+		poolPGX.Store(currentPool)
+	}()
+
+	// Set to nil
+	poolPGX.Store(nil)
+
+	// Should not panic when called on nil pool
+	ClosePool()
+	ClosePool()
+	ClosePool()
+
+	// Should work fine - no panic expected
+}
+
+// TestIsNotFound tests the error checking utility
+func TestIsNotFound(t *testing.T) {
+	// Test with pgx.ErrNoRows
+	if !IsNotFound(pgx.ErrNoRows) {
+		t.Error("IsNotFound should return true for pgx.ErrNoRows")
+	}
+
+	// Test with other errors
+	otherErr := errors.New("some other error")
+	if IsNotFound(otherErr) {
+		t.Error("IsNotFound should return false for non-ErrNoRows errors")
+	}
+
+	// Test with nil
+	if IsNotFound(nil) {
+		t.Error("IsNotFound should return false for nil")
+	}
+}
+
+// TestPgTime tests PostgreSQL timestamp conversion
+func TestPgTime(t *testing.T) {
+	now := time.Now()
+	pgTime := PgTime(now)
+
+	if !pgTime.Valid {
+		t.Error("PgTime should return valid timestamp")
+	}
+
+	if !pgTime.Time.Equal(now) {
+		t.Errorf("PgTime time mismatch: got %v, want %v", pgTime.Time, now)
+	}
+}
+
+// TestPgTimeNow tests current time conversion
+func TestPgTimeNow(t *testing.T) {
+	before := time.Now()
+	pgTime := PgTimeNow()
+	after := time.Now()
+
+	if !pgTime.Valid {
+		t.Error("PgTimeNow should return valid timestamp")
+	}
+
+	// Check that time is between before and after
+	if pgTime.Time.Before(before) || pgTime.Time.After(after) {
+		t.Error("PgTimeNow should return current time")
+	}
+}
+
+// TestTsQueryFunctions tests full-text search query builders
+func TestTsQueryFunctions(t *testing.T) {
+	tests := []struct {
+		name     string
+		fn       func(string) string
+		input    string
+		expected string
+	}{
+		{
+			name:     "TsAndQuery",
+			fn:       TsAndQuery,
+			input:    "hello world",
+			expected: "hello & world",
+		},
+		{
+			name:     "TsPrefixAndQuery",
+			fn:       TsPrefixAndQuery,
+			input:    "hello world",
+			expected: "hello:* & world:*",
+		},
+		{
+			name:     "TsOrQuery",
+			fn:       TsOrQuery,
+			input:    "hello world",
+			expected: "hello | world",
+		},
+		{
+			name:     "TsPrefixOrQuery",
+			fn:       TsPrefixOrQuery,
+			input:    "hello world",
+			expected: "hello:* | world:*",
+		},
+		{
+			name:     "TsAndQuery with multiple words",
+			fn:       TsAndQuery,
+			input:    "one two three",
+			expected: "one & two & three",
+		},
+		{
+			name:     "TsOrQuery with multiple words",
+			fn:       TsOrQuery,
+			input:    "one two three",
+			expected: "one | two | three",
+		},
+		{
+			name:     "TsAndQuery with extra spaces",
+			fn:       TsAndQuery,
+			input:    "hello    world",
+			expected: "hello & world",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := tt.fn(tt.input)
+			if result != tt.expected {
+				t.Errorf("%s(%q) = %q, want %q", tt.name, tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+// TestFieldsWithSuffix tests the internal suffix function
+func TestFieldsWithSuffix(t *testing.T) {
+	result := fieldsWithSufix("hello world", ":*")
+	expected := []string{"hello:*", "world:*"}
+
+	if len(result) != len(expected) {
+		t.Fatalf("fieldsWithSufix length mismatch: got %d, want %d", len(result), len(expected))
+	}
+
+	for i, v := range result {
+		if v != expected[i] {
+			t.Errorf("fieldsWithSufix[%d] = %q, want %q", i, v, expected[i])
+		}
+	}
+}
+
+// TestBeginTxErrorWrapping tests that BeginTx preserves error context
+func TestBeginTxErrorWrapping(t *testing.T) {
+	// This test verifies basic behavior without requiring a database connection
+	// Actual error wrapping would require a failing database connection
+
+	// Skip if no pool initialized (unit test environment)
+	if poolPGX.Load() == nil {
+		t.Skip("Skipping BeginTx test - requires initialized pool")
+	}
+
+	// Just verify the function accepts a context
+	// In a real scenario with a cancelled context, it would return an error
+	ctx := context.Background()
+
+	// We can't fully test without a real DB connection, so just document behavior
+	_, err := BeginTx(ctx)
+	if err != nil {
+		// Error is expected in test environment without valid DB
+		t.Logf("BeginTx returned error (expected in test env): %v", err)
+	}
+}
+
+// TestContextCancellation tests that cancelled context is handled
+func TestContextCancellation(t *testing.T) {
+	// Create an already-cancelled context
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel() // Cancel immediately
+
+	// Note: This test would require an actual database connection to verify
+	// that the context cancellation is properly propagated. We're testing
+	// that the context is accepted by the function signature.
+
+	// The actual behavior would be tested in integration tests
+	// For now, we just verify the function doesn't panic with cancelled context
+
+	// Skip if no pool initialized (unit test environment)
+	if poolPGX.Load() == nil {
+		t.Skip("Skipping context cancellation test - requires initialized pool")
+	}
+
+	// This would return an error about cancelled context in real scenario
+	_, err := BeginTx(ctx)
+	if err == nil {
+		t.Log("BeginTx with cancelled context - error expected in real scenario")
+	}
+}
+
+// TestErrorTypes verifies exported error variables
+func TestErrorTypes(t *testing.T) {
+	if ErrConnStringMissing == nil {
+		t.Error("ErrConnStringMissing should be defined")
+	}
+
+	if ErrInitTX == nil {
+		t.Error("ErrInitTX should be defined")
+	}
+
+	if ErrCommitTX == nil {
+		t.Error("ErrCommitTX should be defined")
+	}
+
+	if ErrNoRows == nil {
+		t.Error("ErrNoRows should be defined")
+	}
+
+	// Check error messages are descriptive
+	if !strings.Contains(ErrConnStringMissing.Error(), "connection string") {
+		t.Error("ErrConnStringMissing should mention connection string")
+	}
+}
+
+// TestStringPoolGetPut tests the string builder pool
+func TestStringPoolGetPut(t *testing.T) {
+	// Get a string builder from pool
+	sb1 := getSB()
+	if sb1 == nil {
+		t.Fatal("getSB should return non-nil string builder")
+	}
+
+	// Use it
+	sb1.WriteString("test")
+	if sb1.String() != "test" {
+		t.Error("String builder should work normally")
+	}
+
+	// Put it back
+	putSB(sb1)
+
+	// Get another one - should be reset
+	sb2 := getSB()
+	if sb2 == nil {
+		t.Fatal("getSB should return non-nil string builder")
+	}
+
+	// Should be empty after reset
+	if sb2.Len() != 0 {
+		t.Error("String builder from pool should be reset")
+	}
+
+	putSB(sb2)
+}
+
+// TestConditionActionTypes tests condition action enum
+func TestConditionActionTypes(t *testing.T) {
+	// Verify enum values are distinct
+	actions := []CondAction{
+		CondActionNothing,
+		CondActionNeedToClose,
+		CondActionSubQuery,
+	}
+
+	seen := make(map[CondAction]bool)
+	for _, action := range actions {
+		if seen[action] {
+			t.Errorf("Duplicate CondAction value: %v", action)
+		}
+		seen[action] = true
+	}
+}
+
+// TestQueryBuilderReuse documents query builder reuse behavior
+// This test verifies that query builders accumulate state and should NOT be reused
+func TestQueryBuilderReuse(t *testing.T) {
+	t.Skip("Query builders are not designed for reuse - this test documents the limitation")
+
+	// This test would require actual database tables to demonstrate the issue
+	// The behavior is:
+	// 1. Creating a base query builder
+	// 2. Adding a WHERE clause
+	// 3. Reusing the same builder with another WHERE clause
+	// 4. The second query would have BOTH WHERE clauses
+	//
+	// Example:
+	// baseQuery := users.User.Select(user.ID, user.Email)
+	// baseQuery.Where(user.ID.Eq(1)) // First query
+	// baseQuery.Where(user.Status.Eq(2)) // Second query has BOTH conditions!
+	//
+	// This is by design - query builders are mutable and single-use.
+	// Each query should create a new builder instance.
+}
+
+// TestQueryBuilderThreadSafety documents that query builders are not thread-safe
+func TestQueryBuilderThreadSafety(t *testing.T) {
+	t.Skip("Query builders are not thread-safe by design - this test documents the limitation")
+
+	// Query builders accumulate state in their internal fields (where, args, etc.)
+	// and do not use any synchronization primitives.
+	//
+	// Sharing a query builder across goroutines will cause race conditions.
+	//
+	// CORRECT usage: Create a new query builder in each goroutine
+	// INCORRECT usage: Share a query builder variable across goroutines
+	//
+	// The connection pool itself IS thread-safe and can be used concurrently.
+}
+
+// TestSelectQueryBuilderBasics tests basic query building
+func TestSelectQueryBuilderBasics(t *testing.T) {
+	// Create a test table
+	testTable := &Table{Name: "users", FieldCount: 10}
+	idField := Field("users.id")
+	emailField := Field("users.email")
+
+	// Test basic select
+	qry := testTable.Select(idField, emailField)
+	sql := qry.String()
+
+	if !strings.Contains(sql, "SELECT") {
+		t.Error("Query should contain SELECT")
+	}
+	if !strings.Contains(sql, "users.id") {
+		t.Error("Query should contain users.id field")
+	}
+	if !strings.Contains(sql, "users.email") {
+		t.Error("Query should contain users.email field")
+	}
+	if !strings.Contains(sql, "FROM users") {
+		t.Error("Query should contain FROM users")
+	}
+}
+
+// TestWhereConditionAccumulation tests that WHERE conditions accumulate
+func TestWhereConditionAccumulation(t *testing.T) {
+	testTable := &Table{Name: "users", FieldCount: 10}
+	idField := Field("users.id")
+	statusField := Field("users.status")
+
+	// Create a query and add multiple WHERE conditions
+	qry := testTable.Select(idField).
+		Where(idField.Eq(1)).
+		Where(statusField.Eq("active"))
+
+	sql := qry.String()
+
+	// Both conditions should be present
+	if !strings.Contains(sql, "WHERE") {
+		t.Error("Query should contain WHERE clause")
+	}
+
+	// Should have multiple conditions (this demonstrates accumulation)
+	if strings.Count(sql, "$") < 2 {
+		t.Error("Query should have multiple parameterized values")
+	}
+}
+
+// TestInsertQueryBuilder tests insert query building
+func TestInsertQueryBuilder(t *testing.T) {
+	testTable := &Table{Name: "users", FieldCount: 10}
+
+	qry := testTable.Insert()
+
+	sql := qry.String()
+
+	if !strings.Contains(sql, "INSERT INTO users") {
+		t.Error("Query should contain INSERT INTO users")
+	}
+}
+
+// TestUpdateQueryBuilder tests update query building
+func TestUpdateQueryBuilder(t *testing.T) {
+	testTable := &Table{Name: "users", FieldCount: 10}
+	idField := Field("users.id")
+
+	qry := testTable.Update().
+		Where(idField.Eq(1))
+
+	sql := qry.String()
+
+	if !strings.Contains(sql, "UPDATE users") {
+		t.Error("Query should contain UPDATE users")
+	}
+	if !strings.Contains(sql, "WHERE") {
+		t.Error("Query should contain WHERE clause")
+	}
+}
+
+// TestDeleteQueryBuilder tests delete query building
+func TestDeleteQueryBuilder(t *testing.T) {
+	testTable := &Table{Name: "users", FieldCount: 10}
+	idField := Field("users.id")
+
+	qry := testTable.Delete().Where(idField.Eq(1))
+
+	sql := qry.String()
+
+	if !strings.Contains(sql, "DELETE FROM users") {
+		t.Error("Query should contain DELETE FROM users")
+	}
+	if !strings.Contains(sql, "WHERE") {
+		t.Error("Query should contain WHERE clause")
+	}
+}
+
+// TestFieldConditioners tests various field condition methods
+func TestFieldConditioners(t *testing.T) {
+	field := Field("users.age")
+
+	tests := []struct {
+		name      string
+		condition Conditioner
+		checkFunc func(string) bool
+	}{
+		{
+			name:      "Eq",
+			condition: field.Eq(25),
+			checkFunc: func(s string) bool { return strings.Contains(s, " = $") },
+		},
+		{
+			name:      "NotEq",
+			condition: field.NotEq(25),
+			checkFunc: func(s string) bool { return strings.Contains(s, " != $") },
+		},
+		{
+			name:      "Gt",
+			condition: field.Gt(25),
+			checkFunc: func(s string) bool { return strings.Contains(s, " > $") },
+		},
+		{
+			name:      "Lt",
+			condition: field.Lt(25),
+			checkFunc: func(s string) bool { return strings.Contains(s, " < $") },
+		},
+		{
+			name:      "Gte",
+			condition: field.Gte(25),
+			checkFunc: func(s string) bool { return strings.Contains(s, " >= $") },
+		},
+		{
+			name:      "Lte",
+			condition: field.Lte(25),
+			checkFunc: func(s string) bool { return strings.Contains(s, " <= $") },
+		},
+		{
+			name:      "IsNull",
+			condition: field.IsNull(),
+			checkFunc: func(s string) bool { return strings.Contains(s, " IS NULL") },
+		},
+		{
+			name:      "IsNotNull",
+			condition: field.IsNotNull(),
+			checkFunc: func(s string) bool { return strings.Contains(s, " IS NOT NULL") },
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Build a simple query to see the condition
+			testTable := &Table{Name: "users", FieldCount: 10}
+			qry := testTable.Select(field).Where(tt.condition)
+			sql := qry.String()
+
+			if !tt.checkFunc(sql) {
+				t.Errorf("%s condition not properly rendered in SQL: %s", tt.name, sql)
+			}
+		})
+	}
+}
+
+// TestFieldFunctions tests SQL function wrappers
+func TestFieldFunctions(t *testing.T) {
+	field := Field("users.count")
+
+	tests := []struct {
+		name     string
+		result   Field
+		contains string
+	}{
+		{
+			name:     "Count",
+			result:   field.Count(),
+			contains: "COUNT(",
+		},
+		{
+			name:     "Sum",
+			result:   field.Sum(),
+			contains: "SUM(",
+		},
+		{
+			name:     "Avg",
+			result:   field.Avg(),
+			contains: "AVG(",
+		},
+		{
+			name:     "Max",
+			result:   field.Max(),
+			contains: "MAX(",
+		},
+		{
+			name:     "Min",
+			result:   field.Min(),
+			contains: "Min(",
+		},
+		{
+			name:     "Lower",
+			result:   field.Lower(),
+			contains: "LOWER(",
+		},
+		{
+			name:     "Upper",
+			result:   field.Upper(),
+			contains: "UPPER(",
+		},
+		{
+			name:     "Trim",
+			result:   field.Trim(),
+			contains: "TRIM(",
+		},
+		{
+			name:     "Asc",
+			result:   field.Asc(),
+			contains: " ASC",
+		},
+		{
+			name:     "Desc",
+			result:   field.Desc(),
+			contains: " DESC",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			resultStr := string(tt.result)
+			if !strings.Contains(resultStr, tt.contains) {
+				t.Errorf("%s should contain %q, got: %s", tt.name, tt.contains, resultStr)
+			}
+		})
+	}
+}
+
+// TestInsertQueryValidation tests that Insert queries validate fields are set
+func TestInsertQueryValidation(t *testing.T) {
+	testTable := &Table{Name: "users", FieldCount: 10}
+	idField := Field("users.id")
+
+	t.Run("Exec without fields", func(t *testing.T) {
+		qry := testTable.Insert()
+		err := qry.Exec(context.Background())
+		if err == nil {
+			t.Error("Insert.Exec() should return error when no fields set")
+		}
+		if !strings.Contains(err.Error(), "no fields to insert") {
+			t.Errorf("Expected error about no fields, got: %v", err)
+		}
+	})
+
+	t.Run("ExecTx without fields", func(t *testing.T) {
+		qry := testTable.Insert()
+		// We can't test ExecTx without a real transaction, but we can test the error is defined
+		err := qry.ExecTx(context.Background(), nil)
+		if err == nil {
+			t.Error("Insert.ExecTx() should return error when no fields set")
+		}
+		if !strings.Contains(err.Error(), "no fields to insert") {
+			t.Errorf("Expected error about no fields, got: %v", err)
+		}
+	})
+
+	t.Run("First without fields", func(t *testing.T) {
+		qry := testTable.Insert().Returning(idField)
+		var id int
+		err := qry.First(context.Background(), &id)
+		if err == nil {
+			t.Error("Insert.First() should return error when no fields set")
+		}
+		if !strings.Contains(err.Error(), "no fields to insert") {
+			t.Errorf("Expected error about no fields, got: %v", err)
+		}
+	})
+
+	t.Run("FirstTx without fields", func(t *testing.T) {
+		qry := testTable.Insert().Returning(idField)
+		var id int
+		err := qry.FirstTx(context.Background(), nil, &id)
+		if err == nil {
+			t.Error("Insert.FirstTx() should return error when no fields set")
+		}
+		if !strings.Contains(err.Error(), "no fields to insert") {
+			t.Errorf("Expected error about no fields, got: %v", err)
+		}
+	})
+}

playground/qry_insert_test.go

@@ -36,7 +36,7 @@ func TestInsertQuery2(t *testing.T) {
 	}
 }
 
-// BenchmarkInsertQuery-12    	 2014519	       584.0 ns/op	    1144 B/op	      18 allocs/op
+// BenchmarkInsertQuery-12    	 2517757	       459.6 ns/op	    1032 B/op	      13 allocs/op
 func BenchmarkInsertQuery(b *testing.B) {
 	for b.Loop() {
 		_ = db.User.Insert().
@@ -50,7 +50,7 @@ func BenchmarkInsertQuery(b *testing.B) {
 	}
 }
 
-// BenchmarkInsertSetMap-12    	 1534039	       777.1 ns/op	    1480 B/op	      20 allocs/op
+// BenchmarkInsertSetMap-12    	 1812555	       644.1 ns/op	    1368 B/op	      15 allocs/op
 func BenchmarkInsertSetMap(b *testing.B) {
 	for b.Loop() {
 		_ = db.User.Insert().

playground/qry_update_test.go

@@ -43,7 +43,7 @@ func TestUpdateQueryValidation(t *testing.T) {
 	}
 }
 
-// BenchmarkUpdateQuery-12    	 2004985	       592.2 ns/op	    1176 B/op	      20 allocs/op
+// BenchmarkUpdateQuery-12    	 2334889	       503.6 ns/op	    1112 B/op	      17 allocs/op
 func BenchmarkUpdateQuery(b *testing.B) {
 	for b.Loop() {
 		_ = db.User.Update().

qry_insert.go

@@ -5,7 +5,7 @@ package pgm
 
 import (
 	"context"
-	"fmt"
+	"errors"
 	"strconv"
 	"strings"
 
@@ -84,21 +84,28 @@ func (q *insertQry) DoNothing() Execute {
 }
 
 func (q *insertQry) DoUpdate(fields ...Field) Execute {
-	var sb strings.Builder
+	sb := getSB()
+	defer putSB(sb)
+
+	sb.WriteString("DO UPDATE SET ")
 	for i, f := range fields {
 		col := f.Name()
-		if i == 0 {
+		if i > 0 {
-			fmt.Fprintf(&sb, "%s = EXCLUDED.%s", col, col)
+			sb.WriteString(", ")
-		} else {
-			fmt.Fprintf(&sb, ", %s = EXCLUDED.%s", col, col)
 		}
+		sb.WriteString(col)
+		sb.WriteString(" = EXCLUDED.")
+		sb.WriteString(col)
 	}
 
-	q.conflictAction = "DO UPDATE SET " + sb.String()
+	q.conflictAction = sb.String()
 	return q
 }
 
 func (q *insertQry) Exec(ctx context.Context) error {
+	if len(q.fields) == 0 {
+		return errors.New("insert query has no fields to insert: call Set() before Exec()")
+	}
 	_, err := poolPGX.Load().Exec(ctx, q.String(), q.args...)
 	if err != nil {
 		return err
@@ -107,6 +114,9 @@ func (q *insertQry) Exec(ctx context.Context) error {
 }
 
 func (q *insertQry) ExecTx(ctx context.Context, tx pgx.Tx) error {
+	if len(q.fields) == 0 {
+		return errors.New("insert query has no fields to insert: call Set() before ExecTx()")
+	}
 	_, err := tx.Exec(ctx, q.String(), q.args...)
 	if err != nil {
 		return err
@@ -116,10 +126,16 @@ func (q *insertQry) ExecTx(ctx context.Context, tx pgx.Tx) error {
 }
 
 func (q *insertQry) First(ctx context.Context, dest ...any) error {
+	if len(q.fields) == 0 {
+		return errors.New("insert query has no fields to insert: call Set() before First()")
+	}
 	return poolPGX.Load().QueryRow(ctx, q.String(), q.args...).Scan(dest...)
 }
 
 func (q *insertQry) FirstTx(ctx context.Context, tx pgx.Tx, dest ...any) error {
+	if len(q.fields) == 0 {
+		return errors.New("insert query has no fields to insert: call Set() before FirstTx()")
+	}
 	return tx.QueryRow(ctx, q.String(), q.args...).Scan(dest...)
 }
 

qry_select.go

@@ -203,7 +203,8 @@ func (q *selectQry) buildJoin(t Table, joinKW string, t1Field, t2Field Field, co
 	defer putSB(sb)
 	sb.Grow(len(str) * 2)
 
-	sb.WriteString(str + " AND ")
+	sb.WriteString(str)
+	sb.WriteString(" AND ")
 
 	var argIdx int
 	for i, c := range cond {
@@ -263,9 +264,13 @@ func (q *selectQry) FirstTx(ctx context.Context, tx pgx.Tx, dest ...any) error {
 
 func (q *selectQry) All(ctx context.Context, row RowsCb) error {
 	rows, err := poolPGX.Load().Query(ctx, q.String(), q.args...)
+	if err != nil {
 		if errors.Is(err, pgx.ErrNoRows) {
 			return ErrNoRows
 		}
+		return err
+	}
+
 	defer rows.Close()
 
 	for rows.Next() {
@@ -274,14 +279,22 @@ func (q *selectQry) All(ctx context.Context, row RowsCb) error {
 		}
 	}
 
+	// Check for errors from iteration
+	if err := rows.Err(); err != nil {
+		return err
+	}
+
 	return nil
 }
 
 func (q *selectQry) AllTx(ctx context.Context, tx pgx.Tx, row RowsCb) error {
 	rows, err := tx.Query(ctx, q.String(), q.args...)
+	if err != nil {
 		if errors.Is(err, pgx.ErrNoRows) {
 			return ErrNoRows
 		}
+		return err
+	}
 	defer rows.Close()
 
 	for rows.Next() {
@@ -290,6 +303,11 @@ func (q *selectQry) AllTx(ctx context.Context, tx pgx.Tx, row RowsCb) error {
 		}
 	}
 
+	// Check for errors from iteration
+	if err := rows.Err(); err != nil {
+		return err
+	}
+
 	return nil
 }