if set concat null yields is not specified, the setting of the 如果不指定,則應(yīng)用
the concat function returns the concatenation of its arguments concat函數(shù)傳回由它的參數(shù)拼接而成的串。
the setting of set concat null yields null is set at execute or run time and not at parse time setconcat_null_yields_null的設(shè)置是在執(zhí)行或運行時設(shè)置的,而不是在分析時設(shè)置的。