Article directory Clustered index Auxiliary index Covering index What is a covering index? Under what circumstances will the optimizer choose to use a covering index? 1. Query operations only need to use the fields in the auxiliary index 2. When performing statistical operations, you can use covering indexes to speed up queries. 3. The query […]
Tag: union
2525. Classify boxes according to rules/union search/dynamic programming
2525. Classify boxes according to rules – LeetCode Give you four integers length, width, height and mass, respectively representing the three dimensions and Quality, please return a string representing the boxcategory. A chest is “Bulky” if the following conditions are met: The box has at least one dimension greater than or equal to 104 . […]
Explanation of structures, enumerations, and unions in C language
Table of Contents 1. Structure 1.1 Structure writing format 1.2 Definition of structure variables 1.3 Structure initialization and access to members 1.4 Structure parameter passing 1.5 Structure memory size calculation 1.6 Structural body position break 1.6.1 How bit breaks allocate space 2. Enumeration 2.1 Value acquisition and assignment of enumerations 2.2 Advantages of enumeration 3. […]
Structure + union + enumeration
Article directory 1. Structure: 1.1 Concept of structure: 1.2 Declaration of structure: 1.3 Self-reference of structure: 1.4 Creation and initialization of structure variables: 1.5 Structure memory alignment: 1.5.1 Alignment rules: 1.5.2 Reasons for memory alignment: 1.5.3 Modify the default alignment number: 1.6 Structure parameter transfer: 1.7 Structure implementation bits: 1.7.1 What is a bit segment: […]
Database foreach union all query lambda expression, lambda expression
Code String accountId = LoginUtils.getLoginAccountId(); log.info(“BaseUserCollectInfoServiceImpl.getMerchantInfoList; Start querying the list of favorite merchants accountId: {}”, accountId); PageInfo<BaseMerchantInfoResp> pageInfo = PageHelper.startPage(req.getPageNum(), req.getPageSize()) .doSelectPageInfo(() -> userCollectInfoMapper.getMerchantInfoList(accountId)); if (pageInfo.getTotal() == 0) { return PageInfoUtils.emptyPageInfo(req); } List<BaseMerchantInfoResp> respList = pageInfo.getList(); List<String> accountIds = respList.stream().map(BaseMerchantInfoResp::getAccountId).collect(Collectors.toList()); if (CollectionUtils.isEmpty(accountIds)) { return pageInfo; } //todo queries the merchant service list. Those that are […]
[C Language] Structure, enumeration, union
Table of Contents 1. Structure 1.1 Declaration of structure 1.2 Special declarations of structures 1.3 Self-reference of structure 1.4 Definition and initialization of structure variables 1.5 Structure memory alignment 1.6 Modify the default alignment number 1.7 Structure parameter passing 2. Enumeration 2.1 Definition of enumeration types 2.2 Advantages of enumeration 3. Union (community) 3.1 Definition […]
Custom types (structure, enumeration, union)
1. Structure 1.1 Meaning A structure is a collection of values that become member variables. Each member variable of the structure can be a variable of different types. 1.2 Structure declaration 1.2.1 Declaration of structure struct tag//structure type { member_list;//member variable list }variable_list;//Structure variable list Example 1: Describe a student struct Stu { char name[20]; […]
Custom types: structure, enumeration, union
Key points of this chapter Structure: Declaration of structure type self-referencing of structures Definition and initialization of structure variables Structure memory alignment Structure parameter passing Structure implements bit fields (filling of bit fields & portability) enumerate: Definition of enumeration type Advantages of enumerations Use of enumerations joint: union type definition Features of the union Union […]
Data structure experiment – merge and find the root of the tree with a high height as the new root + find uses folding rules to implement the union and set experiment
Merge and find the root of the tree with the highest height when merging as the new root Experiment 1.1 Experimental content When the union search is merged, the root node of the tree with a higher height is used as the root node of the new tree to generate a new tree. After merging, […]
Custom types: structure, enumeration, union (2)
2. Bit segment The appearance of bit segments is to save space. 2.1 What is a bit segment The declaration and structure of bit fields are similar, with two differences: 1. Members of the bit field must be int, unsigned int or signed int. 2. There is a colon and a number after the member […]