Function checkDefault

backend/plugin/schema/tidb/walk_through.go:1130–1160

(columnName string, columnType *types.FieldType, value tidbast.ExprNode)

}

func checkDefault(columnName string, columnType *types.FieldType, value tidbast.ExprNode) *storepb.Advice {
	if value.GetType().GetType() != mysql.TypeNull {
		switch columnType.GetType() {
		case mysql.TypeBlob, mysql.TypeTinyBlob, mysql.TypeMediumBlob, mysql.TypeLongBlob, mysql.TypeJSON, mysql.TypeGeometry:
			content := fmt.Sprintf("BLOB, TEXT, GEOMETRY or JSON column `%s` can't have a default value", columnName)
			return &storepb.Advice{
				Status:        storepb.Advice_ERROR,
				Code:          code.InvalidColumnDefault.Int32(),
				Title:         content,
				Content:       content,
				StartPosition: &storepb.Position{Line: 0},
			}
		default:
			// Other column types allow default values
		}
	}

	if valueExpr, yes := value.(tidbast.ValueExpr); yes {
		datum := types.NewDatum(valueExpr.GetValue())
		if _, err := datum.ConvertTo(types.Context{}, columnType); err != nil {
			return &storepb.Advice{
				Status:        storepb.Advice_ERROR,
				Code:          code.InvalidColumnDefault.Int32(),
				Title:         err.Error(),
				Content:       err.Error(),
				StartPosition: &storepb.Position{Line: 0},
			}
		}
	}
	return nil
}

func tidbCreateColumnHelper(t *model.TableMetadata, column *tidbast.ColumnDef, position *tidbast.ColumnPosition) *storepb.Advice {
	if t.GetColumn(column.Name.Name.L) != nil {