SQL对字符串进行排序

假设字符串中只由'A'、'B'、'C'、'D'组成，且长度为7。并设函数REPLICATE(<字符串>,<n>)可以创建一个<字符串>的n个副本的字符串，另外还有REPLACE(<目标字符串>,<老字符串>,<新字符串>)，实现如下：

 BEGIN
 DECLARE inString CHAR(7);
 SET inString = 'DCDBAAB';

 REPLICATE('A', (DATA_LENGTH(inString)-DATA_LENGTH(REPLACE(inString,'A',''))))
 ||
 REPLICATE('B', (DATA_LENGTH(inString)-DATA_LENGTH(REPLACE(inString,'B',''))))
 ||
 REPLICATE('C', (DATA_LENGTH(inString)-DATA_LENGTH(REPLACE(inString,'C',''))))
 ||
 REPLICATE('D', (DATA_LENGTH(inString)-DATA_LENGTH(REPLACE(inString,'D',''))))

 END;