oracleÖØÔØ²Ù×÷·ûµÄÀý×Ó
ת×Ô£ºhttp://download.oracle.com/docs/cd/B13789_01/server.101/b10759/statements_6004.htm
Creating User-Defined Operators: Example
This example creates a very simple functional implementation of equality and then creates an operator that uses the function:
CREATE FUNCTION eq_f(a VARCHAR2, b VARCHAR2) RETURN NUMBER AS
BEGIN
IF a = b THEN RETURN 1;
ELSE RETURN 0;
END IF;
END;
/
CREATE OPERATOR eq_op
BINDING (VARCHAR2, VARCHAR2)
RETURN NUMBER
USING eq_f;
Ïà¹ØÎĵµ£º
Èç¹û²»ÊÇÒòΪÕâ´Î»»hisµÄ·þÎñÆ÷£¬¹À¼ÆÎÒÒ»Ö±Ò²²»»áÓöµ½Õâ¸öÎÊÌ⣬һֱ¾õµÃoracleºÜ¸ßÉ¶ÔËüҲûÓÐÑо¿£¬¿ÉÕâ´Î»»·þÎñÆ÷£¬Æ«Æ«ÈÃÎÒÓöµ½ÁËÒ»¸öÎÊÌ⣬ÕÛÄ¥ÁËÕûÕûÁ½Ì죬ÖÕÓÚÔÚ×òÌì½â¾öµôÁË£¬¼Ç¼ÏÂÀ´£¬ÒÔ±¸ÒÔºóËùÓá£
ÖÜÎåÍíÉÏ»»ÁË·þÎñÆ÷£¬ÖÜÒ»ÔçÉÏ·¢ÏÖ³¬ÉùµÄ¹¤×÷Õ ......
SQL> select * from ta;
ID NAME
---------- --------------------
1 gorey
2 gorey2
SQL> select * from tb;
I ......
Á½¸ö×Ó²éѯ½øÐм¯ºÏÔËÐУ¬ Ìõ¼þ¾ÍÊÇÁ½¸ö²éѯµÄ×ֶθöÊýÒ»Ö£¬ÀàÐÍÒ»Ö£¬×Ö¶ÎÃû¿ÉÒÔ²»Í¬¡£
SQL> select * from ta;
ID NAME
---------- --------------------
1 gorey
&nb ......
TO_DATE¸ñʽ
Day:
dd number 12
dy abbreviated fri
day spelled out friday
ddspth spelled out, ordinal twelfth
Month:
mm number 03
mon abbreviated mar
month spelled out march
Year:
yy two digits 98  ......