http return code explanation:
http://blog.csdn.net/x_chengqq/article/details/51160498
Random visit:
200 normal
400 Bad Request
403 access is Forbidden
404 file or directory not found
405 Method Not Allowed
304 forced cache
302 Temporary redirect Moved Temporatily
301Moved Permanently
500 Server Internal Error
503Service Unavailable Service unavailable
504 Gateway Timeout
505HTTP Version Not Supported The server does not support the HTTP version specified in the request
explain:
1xx - information prompt
2xx - success
3xx - redirect
4xx - Client Error
5xx - server error
Python basics:
1.list_value = ["1", "2", "3", "55", "66"]
Reverse order returns 1.list_value[::-1] 2.list_value.reverse()
2. What is the return value of list_value[:-1] ["1", "2", "3", "55"]
3. Statement:
list_value = ["1", "2", "3", "55", "66"]
[list_value.append("k") for item in list_value]
Can the statement be executed normally? What is the result after execution? Is there a problem with the syntax?
Answer: It can be executed normally, infinite loop, which will lead to memory leak
4. Statement
list_value = ["1", "2", "3", "55", "66"]
a = "a"
print [a.join(item) for item in list_value]
return what? Answer: ['6a6', '5a5', '3', '2', '1']
5. How to judge a folder is a package?
A: Include the __init__.py file
6. How much does the following statement return:
lam = lambda x, y: x + y * y
print lam(10, 20)
Answer: 410
7. Do you know python anonymous functions? Answer: lambda
8. How to replace the following function methods with anonymous functions
def g(x):
return x+1
Answer: g = lambda x: x+1
9. Determine whether a string is a palindrome
Answer: s = "abcdcba" s == s[::-1] String flip
10. Randomly generate 100 numbers, and then write to the file
import random
with open("1.txt", 'wb') as f:
for i in range(1, 101):
n = random.randint (1, 100)
f.write(str(n)+"\n")
11. Deduplicate the list
a = [1, 3, 2, 2, 1, 5, 5, 3]
print list(set(a))
Database basics:
1. Ask a grouped query
A table has fields (company) - company, employee, employee number (primary key), find out how many employees each company has?
The actual group query is to use the company field: select count(company) from employee group by company;
2. What symbolic link is used for strings in Oracle?
Oracle uses || this symbolic connection string such as 'abc' || 'd'
3. How does Oracle perform paging?
Oracle uses rownum for paging, which is the most efficient paging method, and hibernate also uses rownum for oralce paging
select * from
( select rownum r,a from tabName where rownum <= 20 )
where r > 10
4. Briefly describe the use of dml, ddl, and dcl in oracle
Dml data manipulation language, such as select, update, delete, insert
Ddl data definition language, such as create table, drop table, ALTER, etc.
Dcl data control language, such as commit, rollback, grant, invoke, etc.
5. The difference between Delete and truncate
delete is generally used to delete a small number of records, and it is a committed transaction that uses a rollback segment and is displayed. And truncate is used to delete a large amount of data, and implicitly commits the transaction, which is much faster than using delete
6. What statement does Oracle use to assign permissions to users?
GRANT TO statement
7. Which one of exits and in is more efficient to execute in the ORALCE database?
Exits are more efficient than in
8. How to show only duplicate data, or not to show duplicate data
显示重复：select * from tablename group by id having count(*)>1
Do not show duplicates: select * from tablename group by id having count(*)=1
java basics:
1.map traversal
for(Map.Entry entry:map.entrySet()){
Systerm.out.println(entry.getKey(), entry.getValue())
}
2.list traversal
for(int i = 0 ; i < list.size() ; i++) {
system.out.println(list.get(i));
}
3.list deduplication
1. The set collection is deduplicated 2. After traversal, the judgment is assigned to another list collection if(!newList.contains(cd)){newList.add(cd);}
4. Difference between abstract class and interface
5. The realization principle of java polymorphism (belonging to more difficult problems)
Answer: Use abstract classes, interfaces to achieve polymorphism
6. Singleton Pattern
LINUX basics:
1. What are the commonly used linux commands grep, more, tail -f, cat, less , ll, ls, ps, tail
2. How to see threads, find threads
ps -ef |grep 'xxxxx'
3. How to read disk information
df -h
4. Check the network and find a port
netstat -an | findstr 80
tasklist | findstr pid
5. How to view the processes occupying port 8080
lsof -i:8080
6. The permission of a file is: d-rwx_r--_r--, what does it mean?
If the permission is expressed in numerical form, the octal number is: 744 , the file attribute is the d directory