code: func ParseSimpleExprsWithSchema(ctx sessionctx.Context, exprStr string, schema *Schema) ([]Expression, error) {
  	exprStr = "select " + exprStr
  	stmts, warns, err := parser.New().Parse(exprStr, "", "")
  	for _, warn := range warns {
  		ctx.GetSessionVars().StmtCtx.AppendWarning(util.SyntaxWarn(warn))
  	}
  	if err != nil {
  		return nil, util.SyntaxWarn(err)
  	}
  	fields := stmts[0].(*ast.SelectStmt).Fields.Fields
  	exprs := make([]Expression, 0, len(fields))
  	for _, field := range fields {
  		expr, err := RewriteSimpleExprWithSchema(ctx, field.Expr, schema)
  		if err != nil {
  			return nil, err
  		}
  		exprs = append(exprs, expr)
  	}
  	return exprs, nil
  }
docs: // ParseSimpleExprsWithSchema parses simple expression string to Expression.
  // The expression string must only reference the column in the given schema.