慢节奏，再慢点，再慢

摘要： select instr('abc','a') from dual;select instr('abc','bc') from dual;select instr('abc ab','a',1,2) from dual;select instr('abcab','a',-1,2) from dual;select instr('abc','d') from dual;分别返回12510select instr('abcab 阅读全文