同一张表省市县sql查询

一，表的结构

 SELECT * FROM t_unionpay_areacode t

 SELECT * FROM t_unionpay_areacode t WHERE t.`name`LIKE "%林州%";

 ';

 ';

';

 ';

从上面的sql语句我们可以的出来一个规律就是县的paraent_code是市，而市的parent_code是省，此外level还有1,2,3级之分，分别对应着省市县

二，联动查询

2.1，省市左外连接查询

 SELECT
   cy.NAME AS provice,
   cy.CODE AS proviceCode,
   ci.NAME AS city,
   ci.CODE AS cityCode

 FROM
   t_unionpay_areacode cy
   LEFT JOIN t_unionpay_areacode ci
     ON ci.parent_code = cy.CODE
      WHERE cy.NAME='河南省'

2.2，市县左外查询

 SELECT
       cou1.NAME AS city,
       cou1.CODE AS cou1Code,
       cou2.NAME AS country,
       cou2.CODE AS cou2Code
     FROM
       t_unionpay_areacode cou1
       LEFT JOIN t_unionpay_areacode cou2
         ON cou2.parent_code = cou1.CODE 

      AND cou1.NAME='安阳市'

2.3，通过市的code或者name相同两个让省市的左外连接在左外连接市县的左外连接

 SELECT
   cy.NAME AS provice,
   cy.CODE AS proviceCode,
   ci.NAME AS city,
   ci.CODE AS cityCode,
   ct.country AS country,
   ct.cou2Code AS countryCode
 FROM
   t_unionpay_areacode cy
   LEFT JOIN t_unionpay_areacode ci
     ON ci.parent_code = cy.CODE 

   LEFT JOIN
     (SELECT
       cou1.NAME AS city,
       cou1.CODE AS cou1Code,
       cou2.NAME AS country,
       cou2.CODE AS cou2Code
     FROM
       t_unionpay_areacode cou1
       LEFT JOIN t_unionpay_areacode cou2
         ON cou2.parent_code = cou1.CODE 

     ) ct
     ON ci.NAME = ct.city
 ' ;