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{

	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

 *
 * <p>The allowed row and column keys must be supplied when the table is created. The table always
 * contains a mapping for every row key / column pair. The value corresponding to a given row and
 * column is null unless another value is provided.
 *
 * <p>The table's size is constant: the product of the number of supplied row keys and the number of

type Values struct {
	Columns []Column
	Values  [][]interface{}
}

// Name from clause name
func (Values) Name() string {
	return "VALUES"
}

// Build build from clause
func (values Values) Build(builder Builder) {
	if len(values.Columns) > 0 {
		builder.WriteByte('(')
		for idx, column := range values.Columns {
			if idx > 0 {
				builder.WriteByte(',')
			}
			builder.WriteQuoted(column)
		}

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

 * Table} interface.
 *
 * <p>The views returned by {@link #column}, {@link #columnKeySet()}, and {@link #columnMap()} have
 * iterators that don't support {@code remove()}. Otherwise, all optional operations are supported.
 * Null row keys, columns keys, and values are not supported.
 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in

					t.Fatalf("column age comment should be correct, name: %v, column: %#v", columnType.Name(),
						columnType)
				}
			case "code":
				if v, ok := columnType.Unique(); !ok || !v {
					t.Fatalf("column code unique should be correct, name: %v, column: %#v", columnType.Name(),
						columnType)
				}
				if v, ok := columnType.DefaultValue(); !ok || v != "hello" {

type Select struct {
	Distinct   bool
	Columns    []Column
	Expression Expression
}

func (s Select) Name() string {
	return "SELECT"
}

func (s Select) Build(builder Builder) {
	if len(s.Columns) > 0 {
		if s.Distinct {
			builder.WriteString("DISTINCT ")
		}

		for idx, column := range s.Columns {
			if idx > 0 {
				builder.WriteByte(',')
			}

}

// 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()
}

		builder.WriteByte(' ')
	} else {
		if len(onConflict.Columns) > 0 {
			builder.WriteByte('(')
			for idx, column := range onConflict.Columns {
				if idx > 0 {
					builder.WriteByte(',')
				}
				builder.WriteQuoted(column)
			}
			builder.WriteString(`) `)
		}

		if len(onConflict.TargetWhere.Exprs) > 0 {
			builder.WriteString(" WHERE ")
			onConflict.TargetWhere.Build(builder)