What are the proofreading rules of mysql character set
This article introduces what the mysql character set proofreading rules are, the content is very detailed, interested friends can refer to, I hope it can be helpful to you.
Currently, the default calibration rule of mysql is ci except that binary charset is binary, that is, it is case insensitive. Since this kind of verification rule is prone to problems, why should it be defaulted to such a rule? There is an old saying that existence is reasonable. I don't know why mysql adopts such a default rule.
Check the verification rule in oracle. The default is binary. By the way, check the explanation of this parameter in the document:
Http://download.oracle.com/docs/cd/B28359_01/server.111/b28320/initparams145.htm#REFRN10127
Note:
Setting NLS_SORT to anything other than BINARY causes a sort to use a full table scan, regardless of the path chosen by the optimizer. BINARY is the exception because indexes are built according to a binary order of keys. Thus the optimizer can use an index to satisfy the ORDER BY clause when NLS_SORT is set to BINARY. If NLS_SORT is set to any linguistic sort, the optimizer must include a full table scan and a full sort in the execution plan.
Ps: out of the question--
A few days ago, I sighed that the document structure of mysql doesn't matter, but one of the highlights of mysql is that registered users can add comments to online documents. You should know the use of these comments.
Inadvertently found that oracle 11g documents also added a corresponding module, oracle is always constantly absorbing the strengths of others and continuous improvement, like a!
Back to the point, after reading oracle's description of this parameter, I can't help thinking that mysql may be stored by default according to the semantics of linguistic, which is probably the requirement of most of its users. There is no answer for the time being.
The default character set verification rules in 1:mysql are attached:
Alipay@ (none) 10:11:56 > show charset
+-- +
| | Charset | Description | Default collation | Maxlen | |
+-- +
| | dec8 | DEC West European | dec8_swedish_ci | 1 |
| | cp850 | DOS West European | cp850_general_ci | 1 |
| | hp8 | HP West European | hp8_english_ci | 1 |
| | koi8r | KOI8-R Relcom Russian | koi8r_general_ci | 1 |
| | latin1 | cp1252 West European | latin1_swedish_ci | 1 |
| | latin2 | ISO 8859-2 Central European | latin2_general_ci | 1 |
| | swe7 | 7bit Swedish | swe7_swedish_ci | 1 |
| | ascii | US ASCII | ascii_general_ci | 1 |
| | hebrew | ISO 8859-8 Hebrew | hebrew_general_ci | 1 |
| | koi8u | KOI8-U Ukrainian | koi8u_general_ci | 1 |
| | greek | ISO 8859-7 Greek | greek_general_ci | 1 |
| | cp1250 | Windows Central European | cp1250_general_ci | 1 |
| | gbk | GBK Simplified Chinese | gbk_chinese_ci | 2 |
| | latin5 | ISO 8859-9 Turkish | latin5_turkish_ci | 1 |
| | armscii8 | ARMSCII-8 Armenian | armscii8_general_ci | 1 |
| | utf8 | UTF-8 Unicode | utf8_general_ci | 3 |
| | cp866 | DOS Russian | cp866_general_ci | 1 |
| | keybcs2 | DOS Kamenicky Czech-Slovak | keybcs2_general_ci | 1 |
| | macce | Mac Central European | macce_general_ci | 1 |
| | macroman | Mac West European | macroman_general_ci | 1 |
| | cp852 | DOS Central European | cp852_general_ci | 1 |
| | latin7 | ISO 8859-13 Baltic | latin7_general_ci | 1 |
| | cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
| | cp1256 | Windows Arabic | cp1256_general_ci | 1 |
| | cp1257 | Windows Baltic | cp1257_general_ci | 1 |
| | binary | Binary pseudo charset | binary | 1 |
| | geostd8 | GEOSTD8 Georgian | geostd8_general_ci | 1 |
+-- +
27 rows in set (0.00 sec)
2:oracle nls_sort attached
Ops$admin@test > select * from v$version
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0-64bi
Ops$admin@test > select * from v$nls_parameters where parameter = 'NLS_SORT'
PARAMETER VALUE
NLS_SORT BINARY
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