feat: Oracle 驱动完整化——回调体系、版本感知、驱动抽象层与测试套件

- 新增驱动抽象层 driver_adapter（go-ora/godror 双驱动切换）
- 新增 Update/Delete/Query 回调，完善 RETURNING INTO 子句
- 修复 create.go 事务悬挂行 BUG、批量 RowsAffected、主键 WHERE 注入
- 版本感知体系：分页/自增/序列默认值/BOOLEAN/32k VARCHAR2 分级能力判定
- 11g 序列+触发器自增、ON UPDATE 触发器、默认值智能转换
- 升级 go-ora v2.8.19 → v2.9.0
- 单元测试+模块测试+集成测试共 96 个，真实 Oracle 11g 全绿
- 测试 DSN 密码移除，改为 ORACLE_DSN 环境变量注入

clauses/merge_test.go

@@ -0,0 +1,78 @@
+package clauses
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+
+	"gorm.io/gorm/clause"
+)
+
+func TestMergeName(t *testing.T) {
+	var m Merge
+	if got := m.Name(); got != "MERGE" {
+		t.Errorf("Merge.Name() = %q, want %q", got, "MERGE")
+	}
+}
+
+func TestMergeDefaultExcludeName(t *testing.T) {
+	if got := MergeDefaultExcludeName(); got != "exclude" {
+		t.Errorf("MergeDefaultExcludeName() = %q, want %q", got, "exclude")
+	}
+}
+
+func TestMergeBuild(t *testing.T) {
+	merge := Merge{
+		Table: clause.Table{Name: "users"},
+		Using: []clause.Interface{
+			clause.Select{Columns: []clause.Column{{Name: "id"}, {Name: "name"}}},
+			clause.From{Tables: []clause.Table{{Name: "users"}}},
+		},
+		On: []clause.Expression{
+			clause.Eq{Column: clause.Column{Name: "a"}, Value: clause.Column{Name: "b"}},
+		},
+	}
+
+	sql := buildClauseSQL(t, "MERGE", merge)
+
+	for _, want := range []string{
+		"MERGE INTO",                // 前缀 + Insert 构建
+		"USING (",                   // USING 子查询
+		"SELECT id,name FROM users", // USING 子查询内容
+		") exclude ON (",            // exclude 别名 + ON
+		"a = b",                     // ON 条件
+	} {
+		if !strings.Contains(sql, want) {
+			t.Errorf("Merge SQL %q does not contain %q", sql, want)
+		}
+	}
+}
+
+func TestMergeBuildEmpty(t *testing.T) {
+	var merge Merge
+
+	sql := buildClauseSQL(t, "MERGE", merge)
+	if want := "MERGE INTO users USING () exclude ON ()"; sql != want {
+		t.Errorf("empty Merge SQL = %q, want %q", sql, want)
+	}
+}
+
+func TestMergeMergeClause(t *testing.T) {
+	merge := Merge{
+		Table: clause.Table{Name: "users"},
+		On: []clause.Expression{
+			clause.Eq{Column: clause.Column{Name: "a"}, Value: clause.Column{Name: "b"}},
+		},
+	}
+
+	cc := &clause.Clause{}
+	merge.MergeClause(cc)
+
+	if cc.Name != "MERGE" {
+		t.Errorf("MergeClause name = %q, want %q", cc.Name, "MERGE")
+	}
+
+	if got, ok := cc.Expression.(Merge); !ok || !reflect.DeepEqual(got, merge) {
+		t.Errorf("MergeClause expression = %#v, want %#v", cc.Expression, merge)
+	}
+}