Archive for September, 2009

SQL中Select语法

Sep 30th

Posted by Herbert in Database

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以下是摘自MySQL官方关于Select的语法，不过看上去有些复杂。
SELECT
    [ALL | DISTINCT | DISTINCTROW ]
      [HIGH_PRIORITY]
      [STRAIGHT_JOIN]
      [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT]
      [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS]
    select_expr [, select_expr ...]
    [FROM table_references
    [WHERE where_condition]
    [GROUP BY {col_name | expr | position}
      [ASC | DESC], ... [WITH ROLLUP]]
    [HAVING where_condition]
    [ORDER BY {col_name | expr | position}
      [ASC | DESC], ...]
    [LIMIT {[offset,] row_count | row_count OFFSET offset}]
    [PROCEDURE procedure_name(argument_list)]
    [INTO OUTFILE 'file_name' export_options
      | INTO DUMPFILE 'file_name'
      | INTO var_name [, var_name]]
    [FOR UPDATE | LOCK IN SHARE MODE]]

我做了些简化，如下

SELECT [DISTINCT] select_expr [, select_expr ...]
FROM table_references
WHERE where_condition
[GROUP BY {col_name | expr | position} [ASC | DESC]]
[HAVING where_condition]
[ORDER BY  {col_name | expr | position} [ASC | DESC]]
[LIMIT {[offset,] row_count | row_count OFFSET offset}]

The Road Not Taken

Sep 7th

Posted by Herbert in MyLife

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在李开复的日志里，引用了这样的几句诗，

也许多少年后在某个地方，

我将轻声叹息把往事回顾，

一片树林里分出两条路，

而我选了人迹更少的一条，

从此决定了我一生的道路。

这是人生的一个感悟，就像选择了计算机科学与技术这条道路一样，茫然后的执着，一直不懈努力。

下面是侯捷（候俊杰） 先生的一个译本

美国诗人  罗勃.佛洛斯特：没有走的路
Robert Frost’s known poem: The Road Not Taken

黄树林里分叉两条路，TWO roads diverged in a yellow wood,
只可惜我不能都踏行。And sorry I could not travel both

我，单独的旅人，伫立良久，And be one traveler, long I stood
极目眺望一条路的尽头，And looked down one as far as I could
看它隐没在丛林深处。To where it bent in the undergrowth;

於是我选择了另一条路，Then took the other, as just as fair,
一样平直，也许更值得，And having perhaps the better claim,
因为青草茵茵，还未被踏过，Because it was grassy and wanted wear;
若有过往人踪，Had worn them really about the same,
路的状况会相差无几。Though as for that the passing there

那天早晨，两条路都覆盖在枯叶下，And both that morning equally lay
没有践踏的污痕：In leaves no step had trodden black.
啊，原先那条路留给另一天吧！Oh, I kept the first for another day!
明知一条路会引出另一条路，Yet knowing how way leads on to way,
我怀疑我是否会回到原处。I doubted if I should ever come back

在许多许多年以後，在某处，I shall be telling this with a sigh
我会轻轻叹息说：Somewhere ages and ages hence:
黄树林里分叉两条路，而我，Two roads diverged in a wood, and I–
我选择了较少人迹的一条，I took the one less traveled by,
使得一切多麽地不同。And that has made all the difference