code: func SetPBColumnsDefaultValue(ctx sessionctx.Context, pbColumns []*tipb.ColumnInfo, columns []*model.ColumnInfo) error {
  	for i, c := range columns {
  		if c.OriginDefaultValue == nil {
  			continue
  		}
  
  		sessVars := ctx.GetSessionVars()
  		originStrict := sessVars.StrictSQLMode
  		sessVars.StrictSQLMode = false
  		d, err := table.GetColOriginDefaultValue(ctx, c)
  		sessVars.StrictSQLMode = originStrict
  		if err != nil {
  			return err
  		}
  
  		pbColumns[i].DefaultVal, err = tablecodec.EncodeValue(ctx.GetSessionVars().StmtCtx, d)
  		if err != nil {
  			return err
  		}
  	}
  	return nil
  }
docs: // SetPBColumnsDefaultValue sets the default values of tipb.ColumnInfos.