func (t DbType) IsNumeric() bool {
	switch t {
	case Int, Numeric, Float:
		return true
	}
	return false
}
IsNumeric return true if t is Float,Int,Numeric
package ansi
type DbType int
const (
	Zero     DbType = 0
	String   DbType = 1
	Boolean  DbType = 2
	Bytes    DbType = 3
	Date     DbType = 4
	DateTime DbType = 5
	Guid     DbType = 6
	Int     = 11
	Numeric = 12
	Float   = 13
	Var = 21
)
func (t DbType) String() string {
	switch t {
	case Zero:
		return "zero"
	case String:
		return "string"
	case Boolean:
		return "boolean"
	case Bytes:
		return "bytes"
	case Date:
		return "date"
	case DateTime:
		return "dateTime"
	case Guid:
		return "guid"
	case Int:
		return "int"
	case Numeric:
		return "numeric"
	case Float:
		return "float"
	case Var:
		return "var"
	}
	return "unknow"
}
func (t DbType) IsBoolean() bool {
	return t == Boolean
}
func (t DbType) IsInteger() bool {
	return t == Int
}
func (t DbType) IsFloat() bool {
	return t == Float
}