Thinking and Summary of Oracle Row and Column Conversion

Thinking and Summary of Oracle Row and Column Conversion the I have been dealing with Oracle-SQL issues in the past few days, and it involves some things that are not usually used, so I have been depressed here for a long time. Now the problem is solved although not perfect. But still share it with everyone. One of row and column conversion: sum (case when.. then.. else.. end) as statement This may also be the first row-to-column conversion method we have encountered. It can be solved by clever use of summary and judgment statements. First look at a simple basic table: as shown below create table STUDENT (www.2cto.com STUNAME NVARCHAR2(50), SUBJECTNAME NVARCHAR2(50), SUBJECTSCORE NUMBER ) the the There are two people’s grades in the table, and each row represents the grades of each student in this subject. This is also a very common table structure when we first learn SQL. Requirement: Convert the above multi-line values ​​into 2-line values ​​in units of students, so that you can intuitively see the grades of each subject of each student. So there is the following statement. select s.stuname, sum(case when s.subjectname='Chinese' then s.subjectscore else 0 end ) as Chinese score, sum(case when s.subjectname='Mathematics'…