if idx > 0 {
				builder.WriteByte(',')
			}

			builder.WriteQuoted(column.Column)
			if column.Desc {
				builder.WriteString(" DESC")
			}
		}
	}
}

// MergeClause merge order by clauses
func (orderBy OrderBy) MergeClause(clause *Clause) {
	if v, ok := clause.Expression.(OrderBy); ok {
		for i := len(orderBy.Columns) - 1; i >= 0; i-- {
			if orderBy.Columns[i].Reorder {

			clause.Limit{Limit: &limit10, Offset: 20},
			clause.OrderBy{Columns: []clause.OrderByColumn{{Column: clause.PrimaryColumn, Desc: true}}},
		}

		for _, clause := range clauses {
			stmt.AddClause(clause)
		}

		stmt.Build("SELECT", "FROM", "WHERE", "GROUP BY", "LIMIT", "ORDER BY")
		_ = stmt.SQL.String()
	}

	PercentOff       float32          `gorm:"column:percent_off"`
}

type CouponProduct struct {
	CouponId  int    `gorm:"primarykey;size:255"`
	ProductId string `gorm:"primarykey;size:255"`
	Desc      string
}

type Order struct {
	gorm.Model
	Num      string
	Coupon   *Coupon
	CouponID string
}

type Parent struct {
	gorm.Model
	FavChildID uint
	FavChild   *Child

	AssertEqual(t, names2, []string{"distinct", "distinct", "distinct", "distinct-2", "distinct-3"})

	var results []User
	if err := DB.Distinct("name", "age").Where("name like ?", "distinct%").Order("name, age desc").Find(&results).Error; err != nil {
		t.Errorf("failed to query users, got error: %v", err)
	}

	expects := []User{
		{Name: "distinct", Age: 20},
		{Name: "distinct", Age: 18},
		{Name: "distinct-2", Age: 18},

	"gorm.io/gorm/schema"
	"gorm.io/gorm/utils/tests"
)

type UserIndex struct {
	Name         string `gorm:"index"`
	Name2        string `gorm:"index:idx_name,unique"`
	Name3        string `gorm:"index:,sort:desc,collate:utf8,type:btree,length:10,where:name3 != 'jinzhu'"`
	Name4        string `gorm:"uniqueIndex"`
	Name5        int64  `gorm:"index:,class:FULLTEXT,comment:hello \\, world,where:age > 10"`

	Comment string
	Option  string        // WITH PARSER parser_name
	Fields  []IndexOption // Note: IndexOption's Field maybe the same
}

type IndexOption struct {
	*Field
	Expression string
	Sort       string // DESC, ASC
	Collate    string
	Length     int
	priority   int
}

// ParseIndexes parse schema indexes
func (schema *Schema) ParseIndexes() map[string]Index {
	indexes := map[string]Index{}

		stmt.BuildClauses = p.Clauses
		resetBuildClauses = true
	}

	if optimizer, ok := db.Statement.Dest.(StatementModifier); ok {
		optimizer.ModifyStatement(stmt)
	}

	// assign model values
	if stmt.Model == nil {
		stmt.Model = stmt.Dest
	} else if stmt.Dest == nil {
		stmt.Dest = stmt.Model
	}

	// parse model values
	if stmt.Model != nil {

				Columns: []clause.OrderByColumn{{Column: clause.PrimaryColumn, Desc: true}},
			}},
			"SELECT * FROM `users` ORDER BY `users`.`id` DESC", nil,
		},
		{
			[]clause.Interface{
				clause.Select{}, clause.From{}, clause.OrderBy{
					Columns: []clause.OrderByColumn{{Column: clause.PrimaryColumn, Desc: true}},
				}, clause.OrderBy{
					Columns: []clause.OrderByColumn{{Column: clause.Column{Name: "name"}}},

			Config: &gorm.Config{
				NowFunc: func() time.Time { return time.Time{} },
			},
			Statement: &gorm.Statement{
				Settings: sync.Map{},
				Schema:   s,
			},
		},
		ReflectValue: reflect.ValueOf(dest),
		Dest:         dest,
	}

	stmt.Schema = s

	values := ConvertToCreateValues(stmt)
	expected := clause.Values{
		// column has value + defaultValue column has value (which should have a stable order)

			if len(values) > 0 {
				stmt.AddClause(clause.Where{Exprs: []clause.Expression{clause.IN{Column: column, Values: values}}})
			}

			if stmt.ReflectValue.CanAddr() && stmt.Dest != stmt.Model && stmt.Model != nil {
				_, queryValues = schema.GetIdentityFieldValuesMap(stmt.Context, reflect.ValueOf(stmt.Model), stmt.Schema.PrimaryFields)