【SQL练习】有下面一张人员地址表，结构如下，其中地址列中存储的格式为省-市-县（区）

create table tab2(
       name varchar2(20),
       address varchar2(50)
)

insert into tab2(name, address) values ('张三', '湖北-宜昌-五峰');
insert into tab2(name, address) values ('李四', '内蒙古-呼和浩特-清水河');
insert into tab2(name, address) values ('小明', '广东-深圳-宝安');
commit;

select t.name, substr(t.address, instr(t.address, '-', 1, 1) + 1, 
instr(t.address, '-', 1, 2) - instr(t.address, '-', 1, 1) - 1) AS result from tab2 t;

SELECT t.name, REGEXP_SUBSTR(t.address, '[^-]+', 1, 2) AS result FROM tab2 t;