[redis] set type

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One 、Set type

Redis Medium Set The type and java Medium HashSet similar , It can be seen as a value by null Of HashMap, Have and HashMap Similar features ：

• disorder
• Elements cannot be repeated
• Quick search
• Support intersection 、 Combine 、 Difference set and other functions

The basic general commands are shown in the figure above , Here is a detailed introduction ！

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1.1 SADD & SREM & SCARD

• SADD key member …: towards set Add one or more elements to

• SREM key member …: remove set The specified element in

• SCARD key: return set The number of elements in

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1.2 SISMEMBER & SMEMBERS

• SISMEMBER key member: Determine whether an element exists or not set in
• SMEMBERS key : obtain set All the elements in

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1.3 SINTER & SDIFF & SUNION

SINTER key1 key2 …: seek key1 And key2 Intersection

SDIFF key1 key2 …: seek key1 And key2 The difference between the set

SUNION key1 key2 …: seek key1 and key2 Union

Case study ： Use the following data as Redis Of Set Collection to store :· Zhang San's good friends are : Li Si 、 Wang Wu 、 Zhao Liu ; Li Si's good friends are : Wang Wu 、 Pockmarks 、 Two dog utilization Set The command implements the following functions :

• Calculate how many friends Zhang San has

• Calculate what friends Zhang San and Li Si have in common

• Check who is Zhang San's friend but not Li Si's friend

• Who are Li's three and four friends in total

• Judge whether Li Si is Zhang San's good friend

• Judge whether Zhang San is Li Si's good friend

• Remove Li Si from Zhang San's friend list

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