Oracle escape函数的使用

SQL> select * from t_char;A
--------------------
a_b
acb
a%b
a'b
a/b
a\b
%
_
aSQL> select * from t_char where a like 'a_b';A
--------------------
a_b
acb
a%b
a'b
a/b
a\bSQL> select * from t_char where a like 'a\_b' escape '\';A
--------------------
a_b--可见要查询含有通配字符的字符串，必须要使用escape函数 SQL> select * from t_char where a like 'a\'b' escape '\';
ERROR:
ORA-01756: quoted string not properly terminated
SQL> select * from t_char where a like 'a''b' escape '\'; A
--------------------
a'b--但是字符'还是需要用两个''来代替字符串中的单引号 SQL> select * from t_char where a like 'ax_b' escape 'x'; A
--------------------
a_b SQL> select * from t_char where a like 'a''_b' escape ''''; A
--------------------
a_b SQL> select * from t_char where a like 'a_%b' escape '_'; A
--------------------
a%b --可以用其他字符，甚至是“'”、“_”、“%”来用作转义字符，但是一般都使用\，以免发生逻辑错误 SQL> select * from t_char where a like 'a\/b' escape '\';
select * from t_char where a like 'a\/b' escape '\'
                                  *
ERROR at line 1:
ORA-01424: missing or illegal character following the escape character
SQL> select * from t_char where a like 'a_/b' escape '_';
select * from t_char where a like 'a_/b' escape '_'
                                  *
ERROR at line 1:
ORA-01424: missing or illegal character following the escape character SQL> select * from t_char where a like 'a//b' escape '/';A
--------------------
a/bSQL> select * from t_char where a like 'a/\b' escape '/';
select * from t_char where a like 'a/\b' escape '/'
                                  *
ERROR at line 1:
ORA-01424: missing or illegal character following the escape characterSQL> select * from t_char where a like 'a\\b' escape '\';A
--------------------
a\b
--要搜索"/"或者"\"则必须使用与之相同的符号作为转义字符，否则无效     基本上的使用方法就是这些了，还需要注意一点，这里的escape函数，和sqlplus中的escape环境参数毫无关系
SQL> show escape
escape OFF