如何通过char和数字键选择sqlite命令？

Question

山坳中的SQLite数据库中的一些值：

a1b2 
a2b3 
a1b10 
a10b1 

如果在SQL使用order by这将是：

a10b1 
a1b10 
a1b2 
a2b3 

我希望它像objc的NSNumericSearch这样的：

a1b2 
a1b10 
a2b3 
a10b1 

我如何编写SQL语句？

Answer 1

开始通过创建自定义排序功能：

int compare_natural(void *data, int len1, const void *str1, int len2, const void *str2) { 
    if (str1 && len1 > 0 && str2 && len2 > 0) { 
     NSString *s1 = [[NSString alloc] initWithBytesNoCopy:(void *)str1 length:len1 encoding:NSUTF8StringEncoding freeWhenDone:NO]; 
     NSString *s2 = [[NSString alloc] initWithBytesNoCopy:(void *)str2 length:len2 encoding:NSUTF8StringEncoding freeWhenDone:NO]; 

     // The use of NSNumericSearch is required for your need. 
     // The others are options depending on your needs 
     NSComparisonResult res = [s1 compare:s2 options:NSCaseInsensitiveSearch | NSNumericSearch | NSDiacriticInsensitiveSearch]; 

     return res; 
    } else if (str1 && len1 > 0 && (!str2 || len2 == 0)) { 
     return -1; // empty strings to the end of the list (optional) 
    } else if (str2 && len2 > 0 && (!str1 || len1 == 0)) { 
     return 1; // empty strings to the end of the list (optional) 
    } else { 
     return 0; 
    } 
} 

然后注册自定义排序器。这需要在打开数据库后完成。因此它与 “分页BYNUMBER”

SELECT some_col ORDER BY some_col COLLATE BYNUMBER结束

// dbRef is your sqlite3 database reference 
int rc = sqlite3_create_collation(dbRef, "BYNUMBER", SQLITE_UTF8, NULL, &compare_natural); 

然后更新您的查询;