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"}}},
				},
			},

		},
		{
			[]clause.Interface{clause.Select{
				Columns: []clause.Column{clause.PrimaryColumn},
			}, clause.From{}},
			"SELECT `users`.`id` FROM `users`", nil,
		},
		{
			[]clause.Interface{clause.Select{
				Columns: []clause.Column{clause.PrimaryColumn},
			}, clause.Select{
				Columns: []clause.Column{{Name: "name"}},
			}, clause.From{}},
			"SELECT `name` FROM `users`", nil,
		},
		{

						queryConds = append(queryConds, clause.Eq{
							Column: clause.Column{Table: rel.JoinTable.Table, Name: ref.ForeignKey.DBName},
							Value:  ref.PrimaryValue,
						})
					}
				}

				_, foreignValues := schema.GetIdentityFieldValuesMap(db.Statement.Context, db.Statement.ReflectValue, foreignFields)
				column, values := schema.ToQueryValues(table, relForeignKeys, foreignValues)

			clause.Eq{Column: column, Value: (*string)(nil)},
			clause.Eq{Column: column, Value: (*int)(nil)},
			clause.Eq{Column: column, Value: (*bool)(nil)},
			clause.Eq{Column: column, Value: (interface{})(nil)},
			clause.Eq{Column: column, Value: sql.NullString{String: "", Valid: false}},
		},
		Result: "`column-name` IS NULL",
	}, {
		Expressions: []clause.Expression{

			}},
			"SELECT * FROM `users` WHERE `users`.`id` = ? OR `name` <> ? AND `age` > ?",
			[]interface{}{"1", "jinzhu", 18},
		},
		{
			[]clause.Interface{clause.Select{}, clause.From{}, clause.Where{

	for idx, key := range keys {
		assignments[idx] = Assignment{Column: Column{Name: key}, Value: values[key]}
	}
	return assignments
}

func AssignmentColumns(values []string) Set {
	assignments := make([]Assignment, len(values))
	for idx, value := range values {
		assignments[idx] = Assignment{Column: Column{Name: value}, Value: Column{Table: "excluded", Name: value}}
	}
	return assignments

}

// AutoIncrement returns the column is auto increment or not.
func (ct ColumnType) AutoIncrement() (isAutoIncrement bool, ok bool) {
	return ct.AutoIncrementValue.Bool, ct.AutoIncrementValue.Valid
}

// Length returns the column type length for variable length column types
func (ct ColumnType) Length() (length int64, ok bool) {
	if ct.LengthValue.Valid {
		return ct.LengthValue.Int64, true
	}
	return ct.SQLColumnType.Length()
}

							set = append(set, clause.Assignment{Column: clause.Column{Name: field.DBName}, Value: now.UnixNano()})
						} else if field.AutoUpdateTime == schema.UnixMillisecond {
							set = append(set, clause.Assignment{Column: clause.Column{Name: field.DBName}, Value: now.UnixMilli()})
						} else if field.AutoUpdateTime == schema.UnixSecond {
							set = append(set, clause.Assignment{Column: clause.Column{Name: field.DBName}, Value: now.Unix()})

func (ns NamingStrategy) CheckerName(table, column string) string {
	return ns.formatName("chk", table, column)
}

// IndexName generate index name
func (ns NamingStrategy) IndexName(table, column string) string {
	return ns.formatName("idx", table, ns.toDBName(column))
}

// UniqueName generate unique constraint name
func (ns NamingStrategy) UniqueName(table, column string) string {

			clause.Where{Exprs: []clause.Expression{
				clause.Eq{Column: clause.PrimaryColumn, Value: "1"},
				clause.Gt{Column: "age", Value: 18},
				clause.Or(clause.Neq{Column: "name", Value: "jinzhu"}),
			}},
			clause.Where{Exprs: []clause.Expression{
				clause.Or(clause.Gt{Column: "score", Value: 100}, clause.Like{Column: "name", Value: "%linus%"}),
			}},