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Function querydb

Writing functions:

querydb(dbid, sql)

Where dbid is the name of the variable returned by the open function, sql is a special text command or commands in SQL, applicable only to an external database, the type of external database (MYSQL, Oracle or others) depends on the syntax specifications of the SQl language, more details can be found on the Internet by typing in the search bar (in browser, in search engines such as Yandex, Google) - "sql mysql" - case of use of language SQL databases to MySQL database

This function executes instructions written in the SQL language.

 

 

Only for external databases

 

The function that performs a database query is an integral part of many software systems and applications. It allows you to extract, modify and save data stored in the database, ensuring efficient work with information. In this text, we will look at the basic principles of working with such functions and present several examples of their use.

Before you start working with the database query function, you need to make sure that the system is connected to the appropriate database. Connection to the database can be established using connection parameters such as server address, port, database name, user authentication data, and others.

Before executing a database query, you need to determine its type. To do this, special syntactic constructions or functions can be used in the programming language that is used. Requests are usually divided into the following categories:

1. SELECT - requests to select data from the database. They can be used to get information from one or more tables, applying filtering conditions to get the necessary information.

Example:

SELECT * FROM customers WHERE age > 18;

2. INSERT - requests to add data to the database. They allow you to insert a new record into a database table.

Example:

INSERT INTO customers (name, age, email) VALUES ('John Doe', 25, 'john.doe@example.com');

3. UPDATE - requests for updating data in the database. They are used to modify existing records.

Example:

UPDATE customers SET age = 26 WHERE name = 'John Doe';

4. DELETE - requests to delete data from the database. They can be used to delete one or more records from the table.

Example:

DELETE FROM customers WHERE age > 30;

In addition, queries can include additional operators such as JOIN, ORDER BY, GROUP BY, and others. They allow you to combine data from multiple tables, sort and group query results.

Depending on the database technology used, the query function may have different ways of executing queries. For example, you can use the SQL language or specific APIs to work with the database. Some popular programming languages, such as Python or Java, provide convenient libraries for working with databases, simplifying the process of writing query functions.

In conclusion, database query functions play an important role in software development. They provide access to the data stored in the database and allow you to process them efficiently. Queries can be performed to fetch, insert, update, and delete data, and they can also use additional operators for more complex analysis and combining information from different tables. We hope that these examples and descriptions have helped you better understand the database query functions and their importance in software development.

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