code: func DisableParseJSONFlag4Expr(expr Expression) {
  	if _, isColumn := expr.(*Column); isColumn {
  		return
  	}
  	if _, isCorCol := expr.(*CorrelatedColumn); isCorCol {
  		return
  	}
  	expr.GetType().Flag &= ^mysql.ParseToJSONFlag
  }
docs: // DisableParseJSONFlag4Expr disables ParseToJSONFlag for `expr` except Column.
  // We should not *PARSE* a string as JSON under some scenarios. ParseToJSONFlag
  // is 0 for JSON column yet(as well as JSON correlated column), so we can skip
  // it. Moreover, Column.RetType refers to the infoschema, if we modify it, data
  // race may happen if another goroutine read from the infoschema at the same
  // time.