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SELECT Field name FROM Table name On the spot, I whispered... That the keyword FROM indicates the table name to obtain the field information. If the data source is an Excel table, you need to add the dollar sign $after the table name and wrap it in square brackets, such as [Sheet1 $] In fact, the above example is the simplest case where S ...

Chapter 55 SQL function% EXTERNAL Format conversion function that returns an expression in display format. outline %EXTERNAL(expression) %EXTERNAL expression parameter Expression - the expression to convert. A field name, an expression containing a field name, or a function whose return value is a convertible data type, such as DATE ...

Exercises - Part 1 Exercise 1 Create a view that meets the following three conditions (the view name is ViewPractice5_1). Using the product table as the reference table, it is assumed that the table contains 8 rows of data in the initial state. Condition 1: the sales unit price is greater than or equal to 1000 yen.Condition 2: the registrati ...

In this article, I will focus on the enhancement of LINQ query function in EF Core 6. This is the third article in the summary of new features of EF Core 6: Summary of new functions of EF Core 6 (I) Summary of new functions of EF Core 6 (II)​​​​​​​ Summary of new functions of EF Core 6 (III) 1. Better support for GroupBy query EF Core 6. ...

oracle simple introduction oracle concept oracle is a relational database. It has a large database. The large database is composed of one or more instances. Each instance is composed of background processes and logical data. Multiple table spaces and multiple users can be created under one instance. Each user has a default table space, and ...

What is SQL SQL (structured query language): structured query languageSQL is a language for defining and operating data in relational databaseSQL language is simple and grammar is simple, easy to learn and use Common relational database PC side: Oracle, MySQL, SQL Server, Access, DB2, Sybase Embedded \ mobile client: SQLite sqlite lightweight ...

Author|DustSource|Ali Technical Public NumberWrite beforeUnit testing is certainly familiar to our developers, but it can be overlooked for a variety of reasons, especially in projects I come across where a wide variety of issues are found during the quiz phase, and I feel it is necessary to talk about unit testing.Unit tests written for writin ...

1. Dynamic SQL 1.1 what is dynamic SQL? What is dynamic SQL? Dynamic SQL refers to generating different SQL statements according to different conditions. Usually, we operate some different SQL statements, which are directly changed in the code, which is very troublesome. It is very convenient to use dynamic SQL of Mybatis. Using t ...

KingbaseES logical backup and restore tool provides online backup and restore function at database object level. Backup objects include: database pattern surface view constraint jurisdiction trigger function sequence The output format of logical backup includes: Binary SQL script In addition, for table data, it also supports the e ...

Core content of MySQL execution plan As we all know, mysql performs query optimization when executing queries. To put it simply, when executing, first generate an execution plan based on cost and rule optimization, and then execute the query according to the execution plan. This article mainly introduces the meaning of each output item of EXPL ...