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This article mainly introduces "how to use ADO.NET tools". In daily operation, I believe many people have doubts about how to use ADO.NET tools. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the doubts about "how to use ADO.NET tools". Next, please follow the editor to study!

ADO.NET tool in the query lesson we talked about SQL query, which can be used to complete more complex queries. You were just starting to use ACCESS, and you could build a lot of useful queries with design views and wizards.

These are enough for you to master for some time, and its functions can basically meet our needs. SQL language as a general database operation language, ADO.NET tools are not necessary for ACCESS users to master, but sometimes this language must be used in practical work to complete some special work.

Simple SQL language does not contain many statements, but in the process of using it, you need to enter a large number of names of various tables, queries, and fields. In this way, when you create a query involving a large number of fields, you need to enter a lot of text.

The ADO.NET tool is much more troublesome than creating queries with query design views. So when I build a query, I first realize all the basic query functions in the query design view ADO.NET tool, and then switch to SQL view to complete some special queries by writing SQL statements. Let's introduce some SQL languages that are often used in the use of ACCESS.

We said we can switch to the SQL view when creating a query. Let's take a look at how to switch:

SELECT statements are the most commonly used in the SQL language. Let's talk about the SELECT sentence first. The ELECT statement constitutes the core of the SQL database language, and its syntax includes five main clauses.

They are FORM, WHERE, GROUP BY, HAVING and ORDER BY clauses.

The structure of the SELECT statement is like this. SELECT < field list > FROM < table list > ADO.NET tool [WHERE < row selection description >] [GROUP BY < group selection description >] [HAVING < group selection description >] [ORDER BY < sorting description >]

We see the result of this query, which has the same effect as the query designed directly with the query view. In fact, all the database operations in ACCESS are made up of SQL language, and Microsoft just adds more convenient operation guides and visual designs on it.

When we create the same query directly from the design view and switch the view to the ADO.NET tool, you will be surprised to find the same statement in the SQL editor in this view. It seems to be a statement automatically generated by ACCESS. It turns out that ACCESS is also a SQL statement, and then use these statements to operate the database.

Now let's talk about the use of the latter clauses in the SELECT statement. You find that these clauses are adapted by square brackets, which shows that these clauses are optional in the SELECT statement, where the WHERE clause is a row selection declaration clause, which can be used to restrict our selected rows, that is, the records in the table, and these rows can be used as query rows only when the row selection description after WHERE is true, and there can be a variety of constraints in WHERE. These conditions can be joined by logical operators such as the ADO.NET tool.

At this point, the study on "how to use ADO.NET tools" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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