问题现象
函数 lpad、rpad 不支持 length 函数运算改写。
解决方法
业务要求 1：保持 9 位，不足位数前面补 0。
如：1234，结果：000001234。
select lpad(GH_FLAG,9-length(GH_FLAG),'0') from
ics.ASSE_BILL_ITEM_RESULT_4;
目前不支持这种语法，改写为：
select left('000000000',9-length(GH_FLAG))||GH_FLAG from
ics.ASSE_BILL_ITEM_RESULT_4;
业务要求 2：只显示手机号前两位和姓名的第一个字符，其它以*代替。
测试表：
insert into t_01 values('13512345678','赵子龙');
1. 客户使用的是 length(phone)-1，这里用户理解有误，以为是需要补
length(phone)-1 个*，length 函数后有-1，直接报错了：
gbase> select rpad(left(phone,7),length(phone)-1,'*') as phone from t_01;
ERROR 1708 (HY000): [192.168.3.26:5050](GBA-02EX-0005) Failed to query
in gnode:
DETAIL: Query failed.
CAUSE:(GBA-01EX-700) The query includes syntax that is not supported by the
Express engine. Either restructure the query with supported syntax, or enable the
GBase Query Path in the configuration file to execute the query with reduced
performance.
SQL: SELECT /*192.168.3.25_13_32_2017-02-26_22:24:31*/ /*+ TID('79') */
rpad(left(`testdb.t_01`.`phone`, 7), (length(`testdb.t_01`.`phone`) - 1), '*') AS
`phone` FROM `testdb`.`
2. 将-1 去除，汉字后的*显示个数也不正确：
gbase> select phone,name,
-> rpad(left(phone,7),length(phone),'*') as phone,
-> rpad(left(name,1),length(name),'*') as name
-> from t_01;
+-------------+-----------+-------------+-------------+
| phone | name | phone | name |
+-------------+-----------+-------------+-------------+
| 13512345678 | 赵子龙 | 1351234**** | 赵******** |
+-------------+-----------+-------------+-------------+
Phone：后 4 位为*，正确。
name： 后 2 位应为*，因为 length 取的是字节数所以变成了 8 个*。
3. 改为 character_length，直接报错了，按研发的解释，目前 rpad 函数中不支持
使用 character_length。
gbase> select rpad(left(name,1),character_length(name),'*') as name from
t_01;
ERROR 1708 (HY000): [192.168.3.26:5050](GBA-02EX-0005) Failed to query in
gnode:
DETAIL: Query failed.
CAUSE:(GBA-01EX-700) The query includes syntax that is not supported by the
Express engine. Either restructure the query with supported syntax, or enable the
GBase Query Path in the configuration file to execute the query with reduced
performance.
SQL: SELECT /*192.168.3.25_13_26_2017-02-26_22:20:13*/ /*+ TID('76') */
rpad(left(`testdb.t_01`.`name`, 1), char_length(`testdb.t_01`.`name`), '*') AS
`name` FROM `testdb`.`t_01_n
4. 最终采用的方法是自定义一个函数取*个数再与显示字符拼接的方法解决此问
题:
delimiter $$
drop function if exists testdb.f_getstar $$
CREATE FUNCTION testdb.f_getstar(n INT)
RETURNS VARCHAR(100)
BEGIN
DECLARE i INT DEFAULT 0;
DECLARE s VARCHAR(100) DEFAULT '';
myloop: LOOP
SET i = i+1;
SET s = CONCAT(s, '*');
IF i>=n THEN LEAVE myloop;
END IF;
END LOOP myloop;
RETURN s;
END$$
delimiter ;
5. 测试结果：
gbase> select phone,name,
-> left(a.phone,2)||testdb.f_getstar(length(a.phone)-2) as
phone,
-> left(a.name,1)||testdb.f_getstar(CHARACTER_LENGTH(a.name)-
1) as name
-> from testdb.t_01 a ;
+-------------+-----------+-------------+-------+
| phone | name | phone | name |
+-------------+-----------+-------------+-------+
| 13512345678 | 赵子龙 | 13********* | 赵** |
