Use the "reverse" operation to reconstruct data and preserve column names
The "reverse" operation is an important tool for reconstructing tabular data. It can convert the data from column-oriented format to row-oriented format. A common scenario is to extract data and column names from the original table.
Consider the following table called StudentMarks, which tracks student performance in different subjects:
姓名 | 数学 | 科学 | 英语 |
---|---|---|---|
Tilak | 90 | 40 | 60 |
Raj | 30 | 20 | 10 |
The desired output is a reconstructed table with three columns: name, subject and score:
姓名 | 科目 | 分数 |
---|---|---|
Tilak | 数学 | 90 |
Tilak | 科学 | 40 |
Tilak | 英语 | 60 |
To achieve this we can use the "invert" operation as shown below:
select u.name, u.subject, u.marks from student s unpivot ( marks for subject in (Maths, Science, English) ) u;
This query successfully reverses the data in the StudentMarks table while preserving name and account information. The "FOR" clause specifies the column names from which data will be extracted.
As you mentioned, your original query successfully reversed the name and fraction values, but was missing the account column. The modified query solves this problem by including the account column in the final select list.
This solution provides a flexible way to reconstruct tabular data, enabling the extraction of data values and corresponding column names.
The above is the detailed content of How Can I Unpivot Data and Retain Column Names in SQL?. For more information, please follow other related articles on the PHP Chinese website!

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