- Chapter: MySQL常用自带函数
接下来我们再来看看 MySQL 自带的 ORD() 这个函数有什么作用。
ORD() 函数
ORD() 函数返回字符串第一个字符的 ASCII 值。
语法： ORD(string)
举一些简单的例子：
mysql> SELECT ORD('i');
2 +----------+
3 | ORD('i') |
4 +----------+
5 | 105 |
6 +----------+
7 1 row in set或者：
mysql> SELECT ORD('NowaMagic');
2 +------------------+
3 | ORD('NowaMagic') |
4 +------------------+
5 | 78 |
6 +------------------+
7 1 row in set如果汉字又如何呢？
mysql> SELECT ORD('简明现代魔法');
02 +---------------------+
03 | ORD('简明现代魔法') |
04 +---------------------+
05 | 15183488 |
06 +---------------------+
07 1 row in set
08
09 mysql> SELECT ORD('简');
10 +-----------+
11 | ORD('简') |
12 +-----------+
13 | 15183488 |
14 +-----------+
15 1 row in set- 为什么会有 8 位数那么长呢？原因是数据库使用的字符集问题，此处的数据库使用的是 UTF-8，16位表示一个符号。顺便贴一下SQL的执行语句：
mysql> SHOW CHARACTER SET;
02 +----------+-----------------------------+---------------------+--------+
03 | Charset | Description | Default collation | Maxlen |
04 +----------+-----------------------------+---------------------+--------+
05 | big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 |
06 | dec8 | DEC West European | dec8_swedish_ci | 1 |
07 | cp850 | DOS West European | cp850_general_ci | 1 |
08 | hp8 | HP West European | hp8_english_ci | 1 |
09 | koi8r | KOI8-R Relcom Russian | koi8r_general_ci | 1 |
10 | latin1 | cp1252 West European | latin1_swedish_ci | 1 |
11 | latin2 | ISO 8859-2 Central European | latin2_general_ci | 1 |
12 | swe7 | 7bit Swedish | swe7_swedish_ci | 1 |
13 | ascii | US ASCII | ascii_general_ci | 1 |
14 | ujis | EUC-JP Japanese | ujis_japanese_ci | 3 |
15 | sjis | Shift-JIS Japanese | sjis_japanese_ci | 2 |
16 | hebrew | ISO 8859-8 Hebrew | hebrew_general_ci | 1 |
17 | tis620 | TIS620 Thai | tis620_thai_ci | 1 |
18 | euckr | EUC-KR Korean | euckr_korean_ci | 2 |
19 | koi8u | KOI8-U Ukrainian | koi8u_general_ci | 1 |
20 | gb2312 | GB2312 Simplified Chinese | gb2312_chinese_ci | 2 |
21 | greek | ISO 8859-7 Greek | greek_general_ci | 1 |
22 | cp1250 | Windows Central European | cp1250_general_ci | 1 |
23 | gbk | GBK Simplified Chinese | gbk_chinese_ci | 2 |
24 | latin5 | ISO 8859-9 Turkish | latin5_turkish_ci | 1 |
25 | armscii8 | ARMSCII-8 Armenian | armscii8_general_ci | 1 |
26 | utf8 | UTF-8 Unicode | utf8_general_ci | 3 |
27 | ucs2 | UCS-2 Unicode | ucs2_general_ci | 2 |
28 | cp866 | DOS Russian | cp866_general_ci | 1 |
29 | keybcs2 | DOS Kamenicky Czech-Slovak | keybcs2_general_ci | 1 |
30 | macce | Mac Central European | macce_general_ci | 1 |
31 | macroman | Mac West European | macroman_general_ci | 1 |
32 | cp852 | DOS Central European | cp852_general_ci | 1 |
33 | latin7 | ISO 8859-13 Baltic | latin7_general_ci | 1 |
34 | utf8mb4 | UTF-8 Unicode | utf8mb4_general_ci | 4 |
35 | cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
36 | utf16 | UTF-16 Unicode | utf16_general_ci | 4 |
37 | cp1256 | Windows Arabic | cp1256_general_ci | 1 |
38 | cp1257 | Windows Baltic | cp1257_general_ci | 1 |
39 | utf32 | UTF-32 Unicode | utf32_general_ci | 4 |
40 | binary | Binary pseudo charset | binary | 1 |
41 | geostd8 | GEOSTD8 Georgian | geostd8_general_ci | 1 |
42 | cp932 | SJIS for Windows Japanese | cp932_japanese_ci | 2 |
43 | eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci | 3 |
44 +----------+-----------------------------+---------------------+--------+
45 39 rows in set
