asterix set

successfully returned 1. Redis 127.0.0.1:6379> hdel myhash field1 (integer) 1 #再次删除myhash键中字段名为field1的字段, because the previous command has deleted it, because it is not deleted, 0 is returned. Redis 127.0.0.1:6379> hdel myhash field1 (integer) 0 #判断myhash键中是否存在field1字段, because the previous command has deleted it because it returns 0. Redis 127.0.0.1:6379> hexists myhash field1 (integer) 0 #通过hsetnx命令给myhash添加新字段field1, whose value is Stephen, because the field has been deleted, So the command

Set set, List, Set set list Collection System: Collection and Map Interfaces Objects of different storage quantities cannot store basic data types. For example, basic data types are automatically packed. ========================================================== ================ Sub-interfaces of Collection:

Original URL: http://blog.163.com/magicc_love/blog/static/18585366220123111128283/Start PL/SQL Developer character encoding inconsistency errorDatabase Character Set (Al32utf8) and Client character set (ZHS16GBK) are different.Character set conversion may cause unexpected results.Note:you can set the client character

What is the Oracle character set? How to view the database character set? Explains how to modify the character set of oracle.1. What is the Oracle character set? The Oracle character set is a collection of symbols for the interpretation of byte data. It can be divided into d

Set interface of the set framework, Set framework A collection that does not contain repeated elements. To be more precise,Set does not contain element pairs that meet e1.equals (e2)E1 and e2, andContains up to one null element.. In all constructor methods and add, equals, and hashCode protocols, other provisions

Show can describe information about the database system in various forms, such as data tables, fields, server status, and so on. There are roughly the following methods: Show [All] COLUMNS from tbl_name [to db_name] [like ' pattern '] Show CREATE DATABASE db_name Show CREATE TABLE tbl_name Show DATABASES [as ' pattern '] Show [STORAGE] Engines Show ERRORS [LIMIT [Offset,] row_count] Show grants for user Show INDEX from Tbl_name [from Db_name] Show INNODB STATUS Show [BDB] LOGS Show privileges

The role of Dict is to establish a set of keys and a set of value mappings, dict key cannot be duplicated.sometimes, we just want to dict key, do not care about the value of key corresponding to the purpose is to ensure that the elements of this set will not be duplicated, then the set will come in Handy.The

The nature of the data structure set _ set and the nature of the data structure set A set is an unordered aggregation of different objects (called members. Two important features of a set: 1. The members are disordered; 2. Each member only appears once in the

You do not know the character set and encoding (encoding and character set encoding), but do not know the encoding character set. In my previous article, a friend proposed the differences between character sets and encoding. I will discuss it with you here. The difference between character set and encoding is actually

Set quoted_identifier onGoWhat does that mean? SyntaxSet quoted_identifier {on | off} NoteWhen set quoted_identifier is on, the identifiers can be separated by double quotation marks, and the text must be separated by single quotation marks. When setquoted_identifier is off, the identifier cannot be enclosed in quotation marks and must comply with all the rules of the transact-SQL identifier. For more info

Recently learning database principle, the relationship normalization introduced several algorithms, the most basic and most important is to find the attribute set X about a function dependency set F closure. /*8 Week of Kung Fu a database basic principles of schooling, and soon to test, so 5-1 holiday also not planning to go out to play, in the school review, rest and so on. In the process of review, it was

Label:operation Result set In order to fit the test, two tables have been built, and some test data have been added, which are repeatedly recorded as soochow characters. Table: Person_1 wei People 　　　 Table: Person_2 Shu Characters 　　 　　A, Union forms and sets Union can connect two or more result sets to form a "set". all the records of the child result set are

Function:One, you can remove the list, duplicate items in the tupleSecond, can be used for intersection, collection, difference set, etc.def add (self, *args, **kwargs):　　　　　　"" Add " " " S1 = (1,2,3 , 4,2,3,1) S3 = set ( s1) S4 = S3.add (5) print ( s1) print (S3) print (S4) (1, 2, 3, 4 , 2, 3, 1) {1, 2, 3, 4, 5} None def clear (Self, *args, **kwargs):"Clear all elements"S1 = (1,

Tags: structure Repeat statement put multiple SQL class strong SELOperation Result setIn order to fit the test, two tables have been built, and some test data have been added, which are repeatedly recorded as soochow characters. Table: Person_1 wei People 　　　 Table: Person_2 Shu Characters 　　 　　A, Union forms and sets Union can connect two or more result sets to form a "set". all the records of the child result se