ORACLE中ESCAPE关键字用法 换字符用法

英文解释：

It is necessary to use an "escape" character to locate the characters '_' and '%' in a column. The keyword ESCAPE followed by the character used as the delimitor of choice is coded after the string search. For example, '+' is used as the escape character. For example:

SELECT NAME       
FROM XYZ_TABLE           
WHERE NAME LIKE 'XY+_Z+%BC%'ESCAPE '+'   

Result: XY_Z%BCAA

            ...

            XY_Z%BC99

The plus sign '+' can still be used as part of the search string as long as a '+' precedes it. For example:

SELECT NAME        
FROM XYZ_TABLE        
WHERE NAME LIKE 'XY++Z%' ESCAPE '+'    

Result: XY+ZAAAAA

            ... 

            XY+Z99999

汉语解释：

定义：escape关键字经常用于使某些特殊字符，如通配符：'%','_'转义为它们原

来的字符的意义，被定义的转义字符通常使用'\',但是也可以使用其他的符号。

实例（1）：

SQL> select * from t11 where name like '%_%';

NAME
----------
aa_a
aaa
SQL> select * from t11 where name like '%\_%' escape '\';

NAME
----------
aa_a

注意：如果是 '/' 作为检索字符, 必须 用 '/' 作为转义符, 正斜扛也一样.
select * from wan_test where psid like '%//%' escape '/'

实例（2）：

SQL> select * from scott.dept;

    DEPTNO DNAME          LOC
---------- -------------- -------------
        50 U%U            EEE
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON
        60 U%%U           RRR

已选择6行。

--查询DNAME中含有一个%字符的行：

SQL> select * From scott.dept where dname like 'U\%U' escape '\';

    DEPTNO DNAME          LOC
---------- -------------- -------------
        50 U%U            EEE

--查询DNAME中含有两个%字符的行：

SQL> select * From scott.dept where dname like 'U\%\%U' escape '\';

    DEPTNO DNAME          LOC
---------- -------------- -------------
        60 U%%U           RRR