久未露面
好久沒上來…
不過，最近自己確是沒什麼好寫…想寫的事沒有發生，有發生的又不想寫（又或忘記寫）
香港/中國/世界也多姿多采
- 「截取通訊條例」通過
- 程翔案一日審結，但未宣判
- 架仔首相拜靖國神舍
- 以巴戰爭
- 十二大行星？！
(0)大受歡迎
個 blog 三月開，現在已有超過九千八次點擊數字。兩家每日有超過二百次，明天應該過萬！！
全靠 google 同 yahoo…相信各 search engine 佔了當中九十八巴仙，加上自己又佔兩巴仙，剛好一百。
Concatenate Columns in Different Rows
Question:
Consider the following table
create table t (
seq int,
seg varchar2(100)
);
Write a SQL to concatenate the segments of the different rows to return a single string, where the order is specified in the seq column
(閱讀全文)
Detecting “Holes” in a Series
Question:
Consider the following table
While seq is supposed to be a continous series of figures, this is not the case. How to detect the range of “holes” within the data?create table t ( seq int );
For example, assume t contain the following:
t
——-
1
2
6
8
The values indicating 3-5 and 7 should be returned.
The funny part in this question is that you need to return valuesoutside the data. But those data can be derived by the data easily
(閱讀全文)
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