code: func SQLTypeTagHandler(ctx *tagContext) error {
  	ctx.col.SQLType = core.SQLType{Name: ctx.tagName}
  	if len(ctx.params) > 0 {
  		if ctx.tagName == core.Enum {
  			ctx.col.EnumOptions = make(map[string]int)
  			for k, v := range ctx.params {
  				v = strings.TrimSpace(v)
  				v = strings.Trim(v, "'")
  				ctx.col.EnumOptions[v] = k
  			}
  		} else if ctx.tagName == core.Set {
  			ctx.col.SetOptions = make(map[string]int)
  			for k, v := range ctx.params {
  				v = strings.TrimSpace(v)
  				v = strings.Trim(v, "'")
  				ctx.col.SetOptions[v] = k
  			}
  		} else {
  			var err error
  			if len(ctx.params) == 2 {
  				ctx.col.Length, err = strconv.Atoi(ctx.params[0])
  				if err != nil {
  					return err
  				}
  				ctx.col.Length2, err = strconv.Atoi(ctx.params[1])
  				if err != nil {
  					return err
  				}
  			} else if len(ctx.params) == 1 {
  				ctx.col.Length, err = strconv.Atoi(ctx.params[0])
  				if err != nil {
  					return err
  				}
  			}
  		}
  	}
  	return nil
  }
docs: // SQLTypeTagHandler describes SQL Type tag handler