fix: treat negative Limit/Page/Offset values as zero

Fixes gogf#4699

## Changes
- `Limit()`: Convert negative values to 0 for both start and limit parameters
- `Page()`: Convert negative limit values to 0 (returns empty result)
- `Offset()`: Convert negative offsets to 0

## Behavior
- `Limit(-1)` → `LIMIT 0` (returns empty result)
- `Page(1, -10)` → `LIMIT 0` (returns empty result)
- `Offset(-5)` → `OFFSET 0` (equivalent to no offset)

This approach maintains API friendliness by avoiding errors while
ensuring SQL validity across all database drivers.

## Tests
- Added `Test_Issue4699` in `gdb_z_unit_issue_test.go` covering:
  - Single/dual parameter Limit with negative values
  - Page with negative limit parameter
  - Offset with negative value
  - Mixed positive/negative parameter combinations

Author: lingcoder

database/gdb/gdb_model_select.go

@@ -615,12 +615,22 @@ func (m *Model) UnionAll(unions ...*Model) *Model {
 // The parameter `limit` can be either one or two number, if passed two number is passed,
 // it then sets "LIMIT limit[0],limit[1]" statement for the model, or else it sets "LIMIT limit[0]"
 // statement.
+// Note: Negative values are treated as zero.
 func (m *Model) Limit(limit ...int) *Model {
 	model := m.getModel()
 	switch len(limit) {
 	case 1:
+		if limit[0] < 0 {
+			limit[0] = 0
+		}
 		model.limit = limit[0]
 	case 2:
+		if limit[0] < 0 {
+			limit[0] = 0
+		}
+		if limit[1] < 0 {
+			limit[1] = 0
+		}
 		model.start = limit[0]
 		model.limit = limit[1]
 	}
@@ -629,8 +639,12 @@ func (m *Model) Limit(limit ...int) *Model {
 
 // Offset sets the "OFFSET" statement for the model.
 // It only makes sense for some databases like SQLServer, PostgreSQL, etc.
+// Note: Negative values are treated as zero.
 func (m *Model) Offset(offset int) *Model {
 	model := m.getModel()
+	if offset < 0 {
+		offset = 0
+	}
 	model.offset = offset
 	return model
 }
@@ -645,11 +659,15 @@ func (m *Model) Distinct() *Model {
 // Page sets the paging number for the model.
 // The parameter `page` is started from 1 for paging.
 // Note that, it differs that the Limit function starts from 0 for "LIMIT" statement.
+// Note: Negative limit values are treated as zero.
 func (m *Model) Page(page, limit int) *Model {
 	model := m.getModel()
 	if page <= 0 {
 		page = 1
 	}
+	if limit < 0 {
+		limit = 0
+	}
 	model.start = (page - 1) * limit
 	model.limit = limit
 	return model

database/gdb/gdb_z_unit_issue_test.go

@@ -0,0 +1,54 @@
+// Copyright GoFrame Author(https://goframe.org). All Rights Reserved.
+//
+// This Source Code Form is subject to the terms of the MIT License.
+// If a copy of the MIT was not distributed with this file,
+// You can obtain one at https://github.com/gogf/gf.
+
+package gdb
+
+import (
+	"testing"
+
+	"github.com/gogf/gf/v2/test/gtest"
+)
+
+// Test_Issue4699 tests negative values for Limit/Page/Offset should be treated as zero.
+// See https://github.com/gogf/gf/issues/4699
+func Test_Issue4699(t *testing.T) {
+	gtest.C(t, func(t *gtest.T) {
+		// Create a base model for testing
+		m := &Model{}
+
+		// Test Limit with single negative parameter
+		m1 := m.Limit(-1)
+		t.AssertEQ(m1.limit, 0)
+
+		// Test Limit with two parameters (start, limit) where both are negative
+		m2 := m.Limit(-10, -5)
+		t.AssertEQ(m2.start, 0)
+		t.AssertEQ(m2.limit, 0)
+
+		// Test Limit with mixed parameters (negative start, positive limit)
+		m3 := m.Limit(-10, 5)
+		t.AssertEQ(m3.start, 0)
+		t.AssertEQ(m3.limit, 5)
+
+		// Test Page with negative limit
+		m4 := m.Page(1, -10)
+		t.AssertEQ(m4.start, 0)
+		t.AssertEQ(m4.limit, 0)
+
+		// Test Page with negative limit on page 2
+		m5 := m.Page(2, -10)
+		t.AssertEQ(m5.start, 0) // (2-1) * 0 = 0
+		t.AssertEQ(m5.limit, 0)
+
+		// Test Offset with negative value
+		m6 := m.Offset(-5)
+		t.AssertEQ(m6.offset, 0)
+
+		// Test Offset with positive value (sanity check)
+		m7 := m.Offset(10)
+		t.AssertEQ(m7.offset, 10)
+	})
+}