| | | | ||* 3 | BITMAP INDEX Single VALUE | normal_gender_bmx | | | |--------------------------------------------------------------------------------------------------predicate information (identified by Operation ID):---------------------------------------------------1-filter ("Sal" =1000 or "Sal" =1500 or "Sal" =2000 or "Sal" =2500 or "Sal" =3000OR"Sal" =3500 or "Sal" =4000 or "Sal" =4500 or "Sal" =5000)3-access ("GENDER" = ' M ')Statistical informa
: Definition and use of static member functions
# include
void Num_show ();
Class Ccomputer
{Float price;
static float total;
Public:
static int num;//number of objects created
Ccomputer (float i)
{price = i; total+= i; num++;}
void Show ()
{cout
The static void T_show ()//static member function
{num_show ();
cout
}
} ;
float ccomputer::total=0;
int ccomputer::num=0;
void Num_show ()//Output class Ccomputer static data member num
{cout
void Main ()
{ccomputer:: T_show ();//Direct access to stat
Dojo provides some array processing methods to see what's there.
1, element positioning
dojo.indexOf (array,value) dojo.lastIndexOf(array,value)
Function: Returns the position of value in the array and returns 1 if it is not found
Here is an example:
dojo.indexOf(["a", "b", "c","a", "b", "c"], "c")
IndexOf Test
dojo.lastIndexOf(["a", "b", "c","a", "b", "c"], "c")
LastIndexOf test
2, enumeration
dojo.forEach(array,callback)
Or
array.forEach(callback)
return value: None
Function:
(); Set the integral value to 0, the last differential value to NanLoad Gain Properties///void Load_gains ();Save Gain Properties///void Save_gains ();Sets filter Alpha for D-term LPFvoid Set_d_lpf_alpha (int16_t cutoff_frequency, float time_step); Calculating filter coefficients PID
Constructor (abbreviated)
float get_pid (float error, float scaler = 1.0);//Compute the output of the PID controller, similar to the method used above, Different points 1. If the two time calculation is greater
This article is reproduced from http://soft.chinabyte.com/339/9020339.shtml
In the previous article, we learned about the role of the TTL field for IP datagrams in network analysis and how to analyze network failures through TTL. In fact, in the IP protocol header, in addition to the TTL field, there are several fields are very important, this is what we are discussing today, the identifier, flag bit and offset, these 3 fields in the IP datagram Shard and reorganization, is very important field
Note: Tcpdump needs to log in with the root account
First, the application scenario 1
The packet sent by the client, after the server was untied, found the packet wrong?
[Root@ied_224_42_sles10_64]~>tcpdump-i eth1 Port 8029-x
Tcpdump:verbose output suppressed, use-v OR-VV for full protocol decode
Listening on eth1, Link-type EN10MB (Ethernet), capture size bytes
11:03:06.125337 IP 10.18.124.47.4217 > 10.6.224.42.8029:p 651073194:651073233 (km) ACK 1685844515 win 64472
0x0000:
the database with the following data:
Id
NAME
SALARY
100
Jacky
5600
101
Rose
3000
102
John
4500
Requirements:
1. Create the table and enter the appropriate data.
2. Information about its name and salary can be queried based on a specific ID.
3. The employee information is based on a query that is larger than a specific salary.
According to the previous requ
To test the performance gains from a reverse proxy server, test performance data comparisons using a reverse proxy server and not using a reverse proxy server.1. Do not use reverse proxyTest a picture 57817 bytes of a picture to make 1000 requests, the concurrency is 100, the performance data is as follows:After many tests, it was found that Apache processes 4500~5000 requests per second without using a reverse proxy.2. Next, use the varnish reverse p
. First of all, according to condition 1, wages are reduced by 10% to 4500 of wages. Next run the second SQL, because this person's salary is 4500 in the range of 2000 to 4600, need to increase 15%, and finally this person's salary result is 5175, not only not reduced, but increased. If the reverse is done, then the wage of 4600 will turn into a wage reduction. No matter how absurd the rules are, if you wan
employees must pay more than 1000 yuan. If you use check and case to behave as followsThen 1 else 0 end Else 1 end = 1)
If the Check:constraint check_salary check (sex = ' 2 ' and salary > m) is in accordance with the conditions of the female clerk, the male clerk cannot enter it.
four, according to the conditions of the selected update. example, there are the following update conditions 1. Salaries of employees over 5000 are reduced by 10%2. Employees with wages between 2000 and 4600 in
;--conditions 2UPDATE personnelset salary = salary * 1.15WHERE Salary >= and Salary But it's not as simple as it is supposed to be, assuming a personal salary of 5000 bucks. First of all, according to condition 1, wages are reduced by 10% to 4500 of wages. Next run the second SQL, because this person's salary is 4500 in the range of 2000 to 4600, need to increase 15%, and finally this person's salary result
example.Let's give an example.Company A, the company has a rule that female employees must pay more than 1000 yuan. If you use check and case to behave as followsCONSTRAINT check_salary Check (case if sex = ' 2 ' then case when salary > THEN1 ELSE 0 End Else 1 End = 1)If you use check only: CONSTRAINT check_salary check (sex = ' 2 ' and Salary > 1000) The female clerk is in accordance with the conditions, the male staff will not be able to input.four, according to the conditions of the selected
, ' current ', default,, ' no '), ( ' 1324 3626 7532 1935 ', ' 888888 ', 1, ' current ', default, 4500, 4500, ' no ')
System functions
Database system-defined functions, which are built-in functions.
Built-in function callsFROM
function Column alias
Description
The
aggregate function
does this by
UPDATE statements as follows --Condition 1 UPDATE personnel SET salary = salary * 0.9 WHERE Salary >= 5000; --Condition 2 UPDATE personnel SET salary = salary * 1.15 WHERE Salary >= and salary But it's not as simple as it is supposed to be, assuming a personal salary of 5000 bucks. First of all, according to condition 1, wages are reduced by 10% to 4500 of wages. Next run the second SQL, because this person's salary is
5000Sohu 100 4500Google 110 5000$ sort-n-K 2-u Facebook.txtGuge 50 3000Baidu 100 5000Google 110 5000When the settings are sorted by the company's employee domain, and then you add-u, the Sohu line is deleted! The original-u only recognizes the domain that is set with-K and finds the same, deleting the same rows.$ sort-k 1-u Facebook.txtBaidu 100 5000Google 110 5000Guge 50 3000Sohu 100 4500$ sort-k 1.1,1.1-u Facebook.txtBaidu 100 5000Google 110 5000So
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