oracel截取字符串

//取@163.com前面的
SELECT SUBSTR ('test@163.com',1,
INSTR ('test@163.com', '@163.com', -1)-1)
FROM DUAL

//取@163.com后面的
SELECT SUBSTR ('test@163.com',
INSTR ('test@163.com', '@163.com', -1)+1)
FROM DUAL