Confuse of "PRIMARY KEY AUTOINCREMENT"

[Prochg]

func (dialector Dialector) DataTypeOf(field *schema.Field) string { switch field.DataType { case schema.Bool: return "numeric" case schema.Int, schema.Uint: if field.AutoIncrement && !field.PrimaryKey { // https://www.sqlite.org/autoinc.html return "integer PRIMARY KEY AUTOINCREMENT" } else { return "integer" }

why not field.AutoIncrement && field.PrimaryKey => integer PRIMARY KEY AUTOINCREMENT