Oracle time format adjustment tutorial

Oracle time format adjustment tutorial

In Oracle database, time format adjustment is a very common operation, especially in the process of data query, display and processing . This article will introduce how to adjust the time format in the Oracle database and provide specific code examples, hoping to help readers better understand and apply the time format adjustment operation.

1. TO_DATE function

The TO_DATE function in Oracle database is used to convert character date data into date data. Its basic syntax is as follows:

TO_DATE(date_string, format)

Among them, date_string is the date string to be converted, and format is the format of the date string. The following is a specific example:

SELECT TO_DATE('2022-01-01', 'yyyy-mm-dd') FROM dual;

The above code converts the string '2022-01-01' into date data and outputs the result. When using the TO_DATE function, you need to ensure that the format parameter is consistent with the format of date_string, otherwise the conversion will fail.

2. TO_CHAR function

TO_CHAR function is used to convert date data into character data in a specified format. Its basic syntax is as follows:

TO_CHAR(date, format)

Among them, date is the Converted date data, format is the converted date format. The following is an example:

SELECT TO_CHAR(SYSDATE, 'yyyy-MM-dd HH24:MI:SS') FROM dual;

The above code converts the current system time SYSDATE into character data in the format of 'yyyy-MM-dd HH24:MI:SS' and outputs the result.

3. Date formatting symbols

When using the TO_DATE and TO_CHAR functions, you need to understand the meaning of the date formatting symbols in order to correctly specify the date format. The following are some commonly used date formatting symbols and their meanings:

• YYYY: four-digit year
• MM: month (01-12)
• DD: date (01-31)
• HH24: Hour (00-23)
• MI: Minute (00-59)
• SS: Second (00-59)

As needed, other formatting symbols can also be used to meet different time format requirements.

4. Application Example

Next, we will use a specific case to show how to adjust the time format.

Suppose there is a table order_info, which contains fields such as order number and order time. Now the order time needs to be displayed in the format of year-month-day. The following is the corresponding SQL code:

SELECT order_id, TO_CHAR(order_time, 'yyyy-MM-dd') AS formatted_time
FROM order_info;

Through the above code, we can display the order time field order_time in the order_info table in the 'yyyy-MM-dd' format and name it the formatted_time field.

Summary:

This article introduces the method of adjusting time format in Oracle database, including the use of TO_DATE and TO_CHAR functions and the application of date formatting symbols. Through specific examples, readers can better understand and master the skills of time format adjustment. I hope it will be helpful to everyone.

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