OracleÖÐÓëSQLSERVER ISNULLº¯ÊýÏàͬ×÷Óõĺ¯Êý
NVL(Expr1,Expr2)Èç¹ûExpr1ΪNULL£¬·µ»ØExpr2µÄÖµ£¬·ñÔò·µ»ØExpr1µÄÖµ
NVL2(Expr1,Expr2,Expr3)Èç¹ûExpr1ΪNULL£¬·µ»ØExpr2µÄÖµ£¬·ñÔò·µ»ØExpr3µÄÖµ
NULLIF(Expr1,Expr2)Èç¹ûExpr1ºÍExpr2µÄÖµÏàµÈ£¬·µ»ØNULL£¬·ñÔò·µ»ØExpr1µÄÖµ
Ïà¹ØÎĵµ£º
Óαê(CURSOR),ºÜÖØÒª
Óαê:ÓÃÓÚ´¦Àí¶àÐмǼµÄÊÂÎñ
ÓαêÊÇÒ»¸öÖ¸ÏòÉÏÏÂÎĵľä±ú(handle)»òÖ¸Õë,¼òµ¥Ëµ£¬Óαê¾ÍÊÇÒ»¸öÖ¸Õë
1 ´¦ÀíÏÔʽÓαê
ÏÔʽÓα괦ÀíÐè 4¸ö PL/SQL ²½Öè,ÏÔʾÓαêÖ÷ÒªÓÃÓÚ´¦Àí²éѯÓï¾ä
(1) ¶¨ÒåÓαê
¸ñʽ: CURSOR cursor_name [(partment[,parameter]...)] IS s ......
SQL SERVERÁÙʱ±í
Ò²¿ÉÒÔ´´½¨ÁÙʱ±í¡£ÁÙʱ±íÓëÓÀ¾Ã±íÏàËÆ£¬µ«ÁÙʱ±í´æ´¢ÔÚ tempdb ÖУ¬µ±²»ÔÙʹÓÃʱ»á×Ô¶¯É¾³ý¡£
Óб¾µØºÍÈ«¾ÖÁ½ÖÖÀàÐ͵ÄÁÙʱ±í£¬¶þÕßÔÚÃû³Æ¡¢¿É¼ûÐԺͿÉÓÃÐÔÉϾù²»Ïàͬ¡£±¾µØÁÙʱ±íµÄÃû³ÆÒÔµ¥¸öÊý×Ö·ûºÅ (#) ´òÍ·£»
ËüÃǽö¶Ôµ±Ç°µÄÓû§Á¬½ÓÊǿɼûµÄ£»µ±Óû§´Ó Microsoft? SQL Server? 2000 ʵÀý¶Ï ......
ÓÐÈË×ܽáÁËÊý¾Ý¿âÖÐNullÖµµÄ¸ÅÄ±È½Ï¾«Á¶£¬ÕªÂ¼ÈçÏ£º
NullÊÇÊý¾Ý¿âÖÐÌØÓеÄÊý¾ÝÀàÐÍ£¬µ±Ò»Ìõ¼Ç¼µÄij¸öÁÐΪNull£¬Ôò±íʾÕâ¸öÁеÄÖµÊÇδ֪µÄ¡¢ÊDz»È·¶¨µÄ¡£¼ÈÈ»ÊÇδ֪µÄ£¬¾ÍÓÐÎÞÊýÖֵĿÉÄÜÐÔ¡£Òò´Ë£¬Null²¢²»ÊÇÒ»¸öÈ·¶¨µÄÖµ¡£
ÕâÊÇNullµÄÓÉÀ´¡¢Ò²ÊÇNullµÄ»ù´¡£¬ËùÓк ......
ÔÚOracle8i»òÒÔÉÏ°æ±¾ÖУ¬¿ÉÒÔ´´½¨ÒÔÏÂÁ½ÖÖÁÙʱ±í£º
1¡£»á»°ÌØÓеÄÁÙʱ±í
CREATE GLOBAL TEMPORARY <TABLE_NAME> (<column specification>)
ON COMMIT PRESERVE ROWS£»
2¡£ÊÂÎñÌØÓеÄÁÙʱ±í
CREATE GL ......