摘要： 1 Little Miss Mary Nobody seemed to care about Mary. She was born in India, where her father was a British official. He was busy with his work, and he 阅读全文

摘要： 1、SQL JOIN 语法（内连接） 内连接举例（下面的两个sql语句是完全相同的） select * from x,y where x.a = y.a select * from x join y on x.a = y.a 2、引入 ANSI SQL92，是为了 解决 外连接。 3、体会与下面语句 阅读全文

摘要： 1、理解一下：IN 和 EXISTS 2、这个IN语句，怎么换成EXISTS 第一个语句（IN）：独立子查询，速度快。 第二个语句（EXISTS）：相关子查询，速度慢。 3、IN的结果 4、NOT IN的结果 5、NOT IN 和 IN 的结果（含NULL） 继续一个例子： 要先把NULL值过滤掉， 阅读全文

摘要： 12 Long Live Love！ In 1970, two years before his death, Edward said: There are some people who think that I was wrong to give away my crown. But they 阅读全文

摘要： 1、guroup by 2、group by 两个字段（dbt3） 3、参数tmp_table_size，可以优化 group by 语句 4、参数tmp_table_size，默认16M 5、可以查看 created_temp_tables和created_tmp_disk_tables，来确定是 阅读全文

摘要： 11 Paris For the next thirty years the Duke and Duchess lived in Paris. They gave parties and travelled round the world, but they never went back to B 阅读全文

摘要： 1、关于 order by 这里牵涉到一个参数：sort_buffer_size，默认256KB。 可以更改这个参数，变成256MB show status like 'sort%' 注意这个状态：sort_merge_passes show global status like 'sort%' o 阅读全文

摘要： 10 The Wedding The next morning Edward telephoned Wallis from Boulogne. 'Did you listen to me on the radio?' he asked. 'Yes, of course,' she said. 'An 阅读全文

摘要： 1、分区表 2、分区类型 3、分区表--举例 4、关于--PARTITIONS表 5、主键 6、第一范式、第二范式、第三范式 7、show table status 阅读全文

摘要： 9 The Woman I Love A few days later Mr Churchill came to sec Edward at Buckingham Palace. At first the King was quiet.Then he said: 'This is my last n 阅读全文