????1?￠limit(??3?10 μ?20 ì?)
????select * from students order by id limit 9￡?10;
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????·?·¨￡o?úò?°?μ?SQL ó????°?óé?explain￡?
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????3￡?possible_keys￡o2é?ˉ?éò?à?ó?μ??÷òy??￡?
????4￡?key￡oêμ?êê1ó?μ??÷òy￡?
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????6￡?ref￡o??ê?áD??×??ò??”const”￡¨2??÷°×ê2?′òa??￡?￡?
????7￡?rows￡o??ê?MySQL è??a?ú?òμ??yè·?á1????°±?D?é¨?èμ?DDêy￡?
????8￡?extra￡oMySQL μ??¨òé￡?
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????ê1ó?1ì?¨3¤?èμ?êy?YDD￡?????????μ??aê???????ê?1ì?¨????3¤?èμ?±?êy￡??éò?oü
????èYò×±??ì2aμ?￡?μ?ê?ê1ó??é±?3¤?èμ?êy?YDD2?ò??¨á?￡?
????d￡???óúMyISAM ààDíμ?êy?Y±í￡???è?×a??3é1ì?¨3¤?èμ?êy?YáD?éò?ìá??
????D??ü￡?μ?ê????Yμ?????ò2′ó￡?
????6?￠ê1ó?not null oíenum
??????á???áD?¨ò??anot null￡??a?ù?éê1êy?Yμ?3?à′?ü?ì￡??ùDèμ??????ü
????éù￡????ò?ú2é?ˉê±￡?MySQL 2?Dèòa?ì2éê?·?′??úì?ày￡??′null ?μ￡?′ó??ó??ˉ2é
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?????ú?a???é????ó|??????????×a???aenum áDμ??μ￡?MySQL ′|àíμ??ü?ì￡?òò?a?ùóD
????μ?enum ?μ?ú?μí3?ú??ê?ò?±êê?êy?μà′±íê?μ?￡?
????7?￠ê1ó?optimize table
??????óú?-3￡DT??μ?±í￡?èYò×2úéú?é??￡?ê1?ú2é?ˉêy?Y?aê±±?D??áè??ü?àμ?
????′??ì?é￡??μμí2é?ˉD??ü?￡??óD?é±?3¤μ?±í??′??ú′??ì?é???êìa￡??a???êìa??blob
????êy?YààDí?ü?aí?3?￡?òò?a??3?′?±??ˉ·?3￡′ó?￡?éò?í¨1yê1ó?optimize table à′
??????àí?é??￡?±￡?¤êy?Y?aD??ü2????μ￡?ó??ˉ??D?êü?é??ó°?ìμ?êy?Y±í?￡ optimize
????table ?éò?ó?óúMyISAM oíBDB ààDíμ?êy?Y±í?￡êμ?êé?è?o??é????àí·?·¨??ê?ó?
????mysqldump à′×a′?êy?Y±í￡?è?oóê1ó?×a′?oóμ????t2￠??D??¨êy?Y±í￡?
????8?￠ê1ó?procedure analyse()
?????éò?ê1ó?procedure analyse()??ê???ààDíμ??¨òé￡?ê1ó?oü?òμ￥￡??ú
????select ó???oó???óé?procedure analyse()?éò?á?￡?àyè?￡o
????select * from students procedure analyse();
????select * from students procedure analyse(16￡?256);
????μú?tì?ó???òa?óprocedure analyse()2?òa?¨òéo?óD?àóú16 ???μ￡??ò
??????o?óD?àóú256 ×??úμ?enum ààDí￡?è?1???óD?T??￡?ê?3??é?ü?áoü3¤￡?
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????μúò?′??′DD?3ì?select ó???ê±￡?·t???÷??×???2é?ˉμ???±??úèYoí2é?ˉ
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?????o′?￡?1￡o?o′?2é?ˉ￡?3y·?ó? select sql_no_cache ?aí·￡?2￡o?ù?YDèòa???o′?
??????D?ò?select sql_cache ?aí·μ?2é?ˉ￡? query_cache_size￡oéè??2é?ˉ?o′?μ?
????′ó?á1??ˉμ?′óD?￡?±è?a???μ′óμ?2??á±??o′??￡
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