SELECT INSTR('CORPORATE FLOOR','OR', 3, 2)
"Instring" FROM DUAL;
Instring
----------
14SELECT INSTR('CORPORATE FLOOR','OR', -3, 2)
"Reversed Instring"
FROM DUAL;
Reversed Instring
-----------------
2
"Instring" FROM DUAL;
Instring
----------
14SELECT INSTR('CORPORATE FLOOR','OR', -3, 2)
"Reversed Instring"
FROM DUAL;
Reversed Instring
-----------------
2
应该回复是6吧.可为何是0呢.
例子可以详细说明以下吗