Где найти дату вчера в SQL?

Команда SQL для получения даты вчера - это:

SELECT DATEADD(DAY, -1, GETDATE()) AS Yesterday;

Where Date Yesterday in SQL

SQL is a powerful language used for managing and manipulating databases. One common task in SQL is performing queries based on specific dates. In this article, we will explore how to use the "where date yesterday" condition in SQL to retrieve data from the previous day. We will also provide code examples to illustrate the concepts.

Understanding Dates in SQL

Before we dive into the "where date yesterday" condition, let's first understand how dates are represented in SQL. In most database systems, dates are stored as a special datatype, such as "DATE" or "DATETIME". These datatypes provide a way to store and perform operations on dates.

Getting Yesterday's Date

To retrieve data from the previous day, we can use various SQL functions depending on the database system we are using. Here are some commonly used functions:

• GETDATE(): This function returns the current date and time. To get yesterday's date, we can subtract 1 day from the current date.

SELECT DATEADD(day, -1, GETDATE()) AS Yesterday;

• CURRENT_DATE: This function returns the current date without the time component. To get yesterday's date, we can subtract 1 day using the DATE_SUB function.

SELECT DATE_SUB(CURRENT_DATE, INTERVAL 1 DAY) AS Yesterday;

• SYSDATE: This function returns the current date and time. To get yesterday's date, we can subtract 1 day using the INTERVAL keyword.

SELECT SYSDATE - INTERVAL '1' DAY AS Yesterday;

Note: The exact functions and syntax may vary depending on the database system you are using. Make sure to refer to the documentation specific to your database for accurate information.

Using the "Where Date Yesterday" Condition

Now that we know how to retrieve yesterday's date, let's see how we can use it in a query. We can use the "WHERE" clause in SQL to filter data based on a specific condition. In this case, we want to retrieve data from the previous day.

Here is an example of a query that retrieves all records from a table where the date is yesterday:

SELECT * FROM your_table
WHERE date_column = DATEADD(day, -1, GETDATE());

In this example, "your_table" is the name of the table you want to query, and "date_column" is the column that contains the date. The "WHERE" clause filters the records based on the condition that the date in the "date_column" is equal to yesterday's date.

You can modify this query based on your specific requirements. For example, if you want to retrieve records from a specific date range, you can use the "BETWEEN" condition:

SELECT * FROM your_table
WHERE date_column BETWEEN DATEADD(day, -1, GETDATE()) AND GETDATE();

This query retrieves all records from the "your_table" table where the date falls between yesterday and today.

Conclusion

In this article, we discussed how to use the "where date yesterday" condition in SQL to retrieve data from the previous day. We explored different methods to get yesterday's date, such as using the GETDATE(), CURRENT_DATE, and SYSDATE functions. We also learned how to use the "WHERE" clause to filter data based on the date. SQL provides powerful ways to manipulate and query dates, allowing us to perform complex operations on our databases.