Tag：Field name
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【GO】gorm
reference material[1] Connect to database[2] Official documents 1. Introduction gormIs usedormMapping, so you need to define the name of the table to operate onmodel, you need to define one in gostruct， structThe name of is the name of the corresponding table in the database. Note:gormlookupstructWhen the name corresponds to the table name in the database, […]
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Mybatis notes: XML Mapping File
The XML Mapping file refers to the XML configuration file for configuring SQL. It configures the mapping relationship between the interface method of the operation entity class and the corresponding SQL. This article just takes a few learning notes. For more information, please refer to the mybatis Chinese documenthttps://mybatis.org/mybatis-3/zh/sqlmap-xml.html 1. Parametertype configuration Parametertype indicates the […]
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Get the property names of unity and uguui built-in components
Source of demand When reading the source code of ugui, I found that unity added [[serializefield]] tag for private fields, but not for public fields, and in the editor extension, it is also to find the private field with serialization tag for modification. Therefore, it is necessary to know the private field name when developing […]
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MySQL advanced
SQL query process: 1. Establish a connection with MySQL through the client / server communication protocol 2. Query cache, which is a place of MySQL that can optimize queries. If query cache is enabled and exactly the same SQL statements are queried in the process of query cache, the query results will be directly […]
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Xi Excel verification data tools
I summary During development, we have done a lot of Excel import operations, and the verification of data is nothing more than:Non null judgment / Data type judgment / Data validity judgment, combined with my previous verification experience, several tool classes are summarized to save the previous repeated verification work Note: it is learned in […]
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MySQL – keyword and addition, deletion, modification and query
The learning notes from MySQL are written incorrectly. Please give us more advice 1、 Keywords of database Keywords of MySQL database include: SELECT、DISTINCT、FROM、JOIN、ON、WHERE、GROUP BY、HAVING、SUM、COUNT、MAX、AVG、ORDER BY、LIMIT Writing order: SELECT->DISTINCT->FROM->JOIN->ON->WHERE->GROUP BY->HAVING->ORDER BY->LIMIT Required fields: select, from Optional fields: distinct, join, on, where, group by, having, sum, count, Max, AVG, order by, limit Execution sequence: From – > […]
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Vue3 (XII) provide and inject functions
The father passed on to the deeper offspringGenerally, there are two ways to transfer values to the depth level: · provide / inject · vuex provide / inject When you see the word “deep”, you must first think of the provide / inject option in vue2. Yes, the same logic applies in vue3. These two […]
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Basic use of Android room database
Detailed explanation of the development and use of Android database room I Introduction:Room provides an abstraction layer on SQLite to make full use of the powerful functions of SQLite and access the database smoothly.The room contains three main components:Database: contains the database holder and serves as the main access point for the underlying connection of […]
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Flink pit bean object specification
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime); dataStream.filter(data -> “test”.equals(data.getTag())).keyBy(“userId”); …… Execution error: Exception in thread “main” org.apache.flink.api.common.InvalidProgramException: This type (GenericType<com.zixi.User>) cannot be used as key. at org.apache.flink.api.common.operators.Keys$ExpressionKeys.<init>(Keys.java:330) at org.apache.flink.streaming.api.datastream.DataStream.keyBy(DataStream.java:340) at com.zixi.main(UserTest.java:58) terms of settlement:1. Provide default parameterless constructor2. The field name must be declared public
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Android studio utility settings
Development environment of this paper: Android Studio 4.2.1Build #AI-202.7660.26.42.7351085, built on May 11, 2021 Windows 7 6.1 1、 Turn off case sensitive configuration Uncheck matchcase in code completion, that is, the code prompt is not case sensitive. image.png 2、 Set the default file encoding method UTF-8 Set in file encodings image.png 3、 Naming prefix Code […]
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Mysql database foundation (II) table structure
1、 Table structure mysql> desc db1.t1; +———+———-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +———+———-+——+—–+———+——-+ | name | char(5) | YES | | NULL | | | homedir | char(50) | YES | | NULL | | +———+———-+——+—–+———+——-+ |Field name | type | empty | key value | default […]