h****n
发帖数: 45 | 1 How did the 1st generation Napster realize query?
Say, Node A shares its U2.mp3, B shares its U3.mp3... how did the information
stored in central server? in mysql or the owner wrote a small database? --it
seems the load of the central server is pretty high based on the registered
population. |
|
s*****e
发帖数: 18 | 2 【 以下文字转载自 EE 讨论区 】
发信人: science (Science), 信区: EE
标 题: sensor从receive simple query到send/forward 需要多少时间？
发信站: BBS 未名空间站 (Wed Aug 31 11:09:23 2005)
数量级是millisecond吧?google没查到数据.
谢谢。 |
|
f******r
发帖数: 333 | 3 可以这样理解吗？
query就是说我有一个目标关键词了，想通过某种search engine把相关的东西找出来？
index就是把找出的东西目录化了？
retrieval是把找出来的，目录化过的内容挖掘出联系或者新的含义来？
请指教？ |
|
c*****t
发帖数: 1879 | 4 谁能推荐本 sql query optimization 方面的书？能有 parallel 部分的更好。
thx |
|
c******n
发帖数: 4965 | 5 【 以下文字转载自 SiliconValleyClub 俱乐部 】
发信人: creation (努力自由泳50m/45sec !), 信区: SiliconValleyClub
标 题: technical question: search query term correction in Google?
发信站: BBS 未名空间站 (Wed Apr 25 00:05:38 2012, 美东)
if I search "Pizsa " , google knows that most likely I made a typo
and will show results for "Pizza"
how does this work? q-gram (substrings of Pizsa are indexed ... like piz izs
, zsa ... )? or indexing neighboring enumeration of pizza ? |
|
w******t
发帖数: 1422 | 6 I have a table like this
name JOB
-------------------
LEE J102
LEE J301
WANG A88
WANG A2
WANG A301
I need a query so that the result is:
name #jobs job-code
LEE 2 J102-J301
WANG 3 A88-A2-A301
I got problem with column "job-code" Anyone can help? |
|
i**s
发帖数: 97 | 7 YOu can not do that in a simple query.
If you want to implement in server, write Stored procedure
using cursor;
If you want to implement in client, that is much easier. |
|
q*j
发帖数: 156 | 8 what do you mean by querying the whole structure of the tree? |
|
j****i
发帖数: 496 | 9 Your question is a little bit vague.
Let's suppose you know the height of the query tree to be 3...
Select ID From Tree
Where ParentID In
(Select ID From Tree
Where ParentID In
(Select ID From Tree
Where ParentID = root
)
)
Union
Select ID From Tree
Where ParentID In
(Select ID From Tree
Where ParentID = root
)
Union
Select ID From Tree
Where ParentID = root
Union
Select ID From Tree
Where ID = root
It may be easier to implement this if you embed SQL into some prog |
|
o**k
发帖数: 5 | 10 In DB2 a table have a field called time ,
time is of timestamp datatype.
How to write a query to retrieve lateset
5 time entries?
for example table person have an age field,
create table person(
name varhar(20),
age timestamp
)
find the youngest 5 person.
Thank |
|
w*s
发帖数: 8 | 11 The chinese text displayed properly inside ms-acess database
on Windows2000 professional. However, when I use jsp to
diaply the query results on web, the chinese text could not
be displayed. Even if I add something like
content="text/html; charset=gb2312"
It still does not work.
Could anyone give me some advice?
Thanks!
Jim |
|
a*p
发帖数: 62 | 12 seems that mysql will add unicode support in the near future.
when I query like "%猪%"
it will return lots of unrelated items, which might contain the two bytes
of 猪 but not belonging to the same chinese character.
true? |
|
lx
发帖数: 28 | 13 I have the impression that data mining is very complicated
query, is that correct? |
|
h****r
发帖数: 2056 | 14 professor's requirements: Create a script that1) generates optimizer
statistics on tables,
then2) explains the access plan for a “complex”
query (must access at least 2 tables).
Have no idea of what is this at all.
thanks |
|
s**********i
发帖数: 711 | 15
under what situation you have problem?
I can use it directly in my SQL queries. |
|
m**a
发帖数: 119 | 16 What's Ad Hoc Queries? I'm new in DB. please don't peng. |
|
h***i
发帖数: 11 | 17 ok. now i am using this query:
select fieldUserID, max(fieldvisitTime) as lastTime, fieldIP from T1 group by
fieldUserID
but the problem is, it will not return the "corresponding fieldIP". simply
it just pick the first IP for each userID group.
:(
so how?
thx |
|
h**********r
发帖数: 174 | 18 The case is like this:
I created an SQL statement as a string in the VBA code, how do I save it
as a query so I can use it later.
Thanks. |
|
l*****k
发帖数: 587 | 19 how do I design an interface that let user browse entries
in query results one by one... like to have a left/right arrow
to do... what is usually used in this kind of programming?
thanks |
|
p*********e
发帖数: 204 | 20 What kind of tool do you use for the user interface? For example, if you
choose Access, you can use the query as the record source, and choose Single
Form as the default view. Then you can add forward and backward buttons or use
the default buttons provided by Access. |
|
m*****r
发帖数: 4 | 21 请问QUERY操作的性能, 也就是在最短的时间内找到需要的RECORD, 和什么有关?
和RECORD的位置有关吗? 多谢 |
|
y****i
发帖数: 5690 | 22 It can be related to a lot of things.
wheter you have index on the fields you are querying at
order of where clauses
RECORD的位置? You first need to define what that is, physical position in
hard disk or something ? |
|
c**t
发帖数: 2744 | 23 一个复杂的Query运行时间太长，怎么知道是什么地方stall? |
|
aw
发帖数: 127 | 24 i don't know access, but = null is wrong in sql server.
another thing you can try is to copy the first table and remove the new
column, run the same query and see if it can work fine as before.
((([dbo_HRPEOPLE_ADDRESSES11].[ADDRESS_TYPE])=[dbo_HRPEOPLE11].[PRIMARY_MAIL_T |
|
w******i
发帖数: 1476 | 25 I run it from Access2000 (Query) SQL View. Should it be the application?
thanks!
that |
|
aw
发帖数: 127 | 26 try to rebuild the queries.
the
summary
object
new
me |
|
w******i
发帖数: 1476 | 27 Thanks! I tried another way to do the nested queries and the problem got
solved.
application? |
|
n****f
发帖数: 905 | 28 希望能抛砖引玉:
如果是 ORACLE，对于语言来讲的话:
第一, 复习一下 HINT, HINT 的种类和使用方法.
如: /* + FIRST_ROWS */, /* + ALL_ROWS */, /* + CHOOSE */ 等.
第二, 复习一下对与大小不同的 TABLES, 什么排练顺序是最快的.
A has 10000000000 rows
B has 1000 rows
SELECT A.*, B.*
FROM A, B
WHERE A.ID = B.ID
OR
SELECT A.*, B.*
FROM B, A
WHERE B.ID = A.ID
==> Which One should be the driving TABLE ?
第三, 如何建立 INDEX 和组合 INDEX.
在什么时候 QUERY 将进行到 FULL SCAN 而不使用 INDEX?
(注意: 在使用FUNTION 比较时, 象:
SELECT .....
FROM ......
WHERE
UPPER(A) = UPPER(B)
时, A OR B 将进行 FULL TABLE SCA |
|
b**e
发帖数: 2 | 29 For your first question, and for the second onw it's pretty much same.
Sorry it's not simple. We have to wait for Yukon to write simple recursive
queries
(For microsoft sql server)
Create Table #tmpTABLE (ID int, parent_id int, lastName varchar(50), firstName
varchar(50) )
declare xTmp scroll cursor for SELECT * from tablename
open xTmp
declare @myid int
declare @pid int
declare @lName varchar(50)
declare @fName varchar(50)
declare @found bit
declare @tmpID int
declare @tmpPID int
declare @num i |
|
P****e
发帖数: 385 | 30 两个table如下
Table: NAMES
NI_NUMBER: varchar(20)
FULL_NAME: varchar(50)
Table: PHONE
NI_NUMBER: varchar(20)
TELEPHONE: varchar(50)
要找到所有没有电话号码的人：
这个办法是没问题的：
SELECT FULL_NAME FROM NAMES
WHERE NI_NUMBER NOT IN
(SELECT DISTINCT NI_NUMBERS FROM PHONE)
可是下面两个query，一个用minus,一个用outer join为什么不能work呢？应该怎么写？
SELECT FULL_NAME FROM NAMES
WHERE NI_NUMBER IN
(SELECT NI_NUMBER FROM NAMES
MINUS
SELCT DISTINCT NI_NUMBER FROM PHONE)
SELECT FULL_NAME FROM
(SELECT A1.FULL_NAME, A2.TELEPHONE
FROM NAMES A1, PHONE A2
WHE |
|
y*l
发帖数: 334 | 31 write a query to display the number of products, the total product
quantity,highest&lowest value,but the average only for non-continued
products(product status is null).
I wrote like this:
SELECT COUNT(*)'prodNumberOfRows', SUM(prodQtyInv)'prodQtyInvAmount',
MAX(prodQtyInv)'prodhighestQtyInv', MIN(prodQtyInv)'prodLowestQtyInv',
AVG(prodQtyInv)'prodAvgQtyInv'
FROM Product
WHERE prodStatus is null;
However, it turns out that all the results are restricted to the "null" |
|
w*****y
发帖数: 35 | 32 SQL Server 支持吗？
GOOGLE研究了一下， 好像要用temporary table 或者用啥 "WITH". 没太懂。
哪位大虾给这个QUERY 个简单答案吧。 |
|
s******n
发帖数: 45 | 33 simple query can't do this bah? at least u need a sproc with cursor... |
|
r***e
发帖数: 31 | 34 I have two relations A(a1,a2), B(b1,b2). I want to update the value of b2 to
a2 if a1 and b1 has the same value. How to write a query? |
|
s****s
发帖数: 42 | 35 List the serial number of the car which has the shortest life span.
My code like this:
select serialno, min(lifespan)
from
(select d.serialno as serialno,
(d.ddate - c.pyear) as lifespan
from destruction d, car c
where d.serialno = c.serialno)
result
group by serialno;
It displayed the following table, but the query required to only display the
third row. How to make it?
SERIALNO MIN(LIFESPAN) |
|
c***y
发帖数: 114 | 36 thanks!
hmm.. seems mysql doesn't support EXCEPT, doesn't support nested queries
neither |
|
s*******n
发帖数: 15 | 37 The query won't allow a blank column, will it? |
|
s******r
发帖数: 1524 | 38 update table2 set table2.maxday = (select max(day) from table1);
Table2 have only one record. table1 have more than 10,000 records. Want to get
max(date) and update table2.
run it and got error message:
"Operation Must Be Updatable Query". I know it is the link problem. No idea ho
w to deal with it or is there any other way to work on it? Thanks. Help please
. |
|
m*****e
发帖数: 126 | 39 问题简化如下：两个table，
player table: playerid int, ...... other fields do not matter
game table: gameid int, player1 int, player2 int ...... other fields do not
matter
game table 中player1, player2分别对应player table中的playerid
请问如何用SELECT Query得到交锋次数最多的几对player. |
|
d******r
发帖数: 16947 | 40 hi,
I have two tables
T1 T2
name Course
A1 C1
A2 C2
A3
how can I use SQL query to have the following one:
name course
A1 C1
A1 C2
A2 C1
A2 C2
A3 C1
A3 C2
Thanks a lot |
|
f****s
发帖数: 315 | 41 what is nestloop? is it sub-query? could you give me an example for that?
Thanks! |
|
x***e
发帖数: 2449 | 42 you have a table called order history.
there are 3 columns in the table:
order_id (unique, indexed)
customer_ID (not unique, indexed)
order_date.(not null)
your boss asked you to find out customers who ordered within last 30 days
and how many orders they made during this timeframe as a second column.
"group by with where clause, .." you said to yourself
You figured out the query successfully and gave it to you boss.
Here come his another question:
"I also want to know the customers who have orde |
|
a*******t
发帖数: 891 | 43 I don't understand how this query is able to return a row number for
repeating IDs.
Can big cow explain how?
table: |
|
|
a*******t
发帖数: 891 | 45 OK, here is a full working example:
CREATE TABLE [dbo].[testing](
[OrderID] [varchar](50) NULL,
[CustName] [varchar](50) NULL
)
and then insert some sample data into the table
123, John
567, Joe
123, Mary
123, Peter
and then here is the query
select
OrderID
, max(case rowno when 0 then CustName end) +
coalesce(max(case rowno when 1 then ', ' + CustName end), '') +
coalesce(max(case rowno when 2 then ', ' + CustName end), '') +
coalesce(max(case rowno when 3 then ', ' + |
|
f*****e
发帖数: 5177 | 46
query 的要求就是，像你说的
如果table1中有记录就update，没有就insert
Query1是严格按照这个逻辑走的。
Query3是是不管有没有，都delete了。然后再insert |
|
j*****n
发帖数: 1781 | 47 not exactly, it depends.
say the server is highly transactional, simply delete first (3) will block
all other concurrent queries (exclusive lock on certain rows if exist). |
|
m*******o
发帖数: 264 | 48 column1 column2 column3
a b 2
a c 4
b d 9
a c 7
Query以后，把column1和column2完全相同的行输出，并把column3的结果相加：
a c 11 |
|
d*******8
发帖数: 3182 | 49 oracle, 3个tables，每个超过1m条数据，table A 有 ID 。table B 有 ID 和B_ITEM,
table C 有 ID 和C_ITEM，问题就是那种query 运行速度快？
1，select * from A
inner join B on ...
inner join C on ...
where B_ITEM = 123 and C_ITEM =456
2, select * from A where ID in (select ID from B where B_ITEM=123 union all
select ID form C where C_ITEM=456 )
3, 还有更有的方案吗？
另外，REGEXP_LIKE() 与REGEXP_INSTR() 那个快？
谢谢。 |
|
B*****g
发帖数: 34098 | 50 晕，1M的要做query的table没有index，赞一个。
另一个问题不会。
REGEXP_ |
|
