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    <p>Since the author was not kind enough to give the SQL to create the schema, here it is for anyone who wants to try the solution from @Eric.</p> <pre><code>create table markdetails (studid, subjectid, marks); create table student_info (studid, name); insert into markdetails values('A1', 3, 50); insert into markdetails values('A1', 4, 60); insert into markdetails values('A1', 5, 70); insert into markdetails values('B1', 3, 60); insert into markdetails values('B1', 4, 80); insert into markdetails values('C1', 5, 95); insert into student_info values('A1', 'Raam'); insert into student_info values('B1', 'Vivek'); insert into student_info values('C1', 'Alex'); </code></pre> <p>Here is an alternative solution using <code>case</code> with <code>group by</code>. </p> <pre><code>select si.studid, si.name, sum(case when md.subjectid = 3 then md.marks end) subjectid_3, sum(case when md.subjectid = 4 then md.marks end) subjectid_4, sum(case when md.subjectid = 5 then md.marks end) subjectid_5 from student_info si join markdetails md on md.studid = si.studid group by si.studid, si.name ; </code></pre> <p>For comparison, here is the same select statement from @Eric's solution:</p> <pre><code>select u.stuid, u.name, s3.marks as subjectid_3, s4.marks as subjectid_4, s5.marks as subjectid_5 from student_temp u left outer join markdetails s3 on u.stuid = s3.stuid and s3.subjectid = 3 left outer join markdetails s4 on u.stuid = s4.stuid and s4.subjectid = 4 left outer join markdetails s5 on u.stuid = s5.stuid and s5.subjectid = 5 ; </code></pre> <p>It will be interesting to see which one would perform better when there is a lot of data.</p>
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    1. COI had the opportunity to sort of test this, on a table with about 150,000 rows. One complication is that I don't know the number of columns in advance, so I have to do a little pre-processing to determine the number of needed columns. Also, not all rows have the same number of data. With the outer join method, it took my PC 50 seconds. With the case when method, it took 15 seconds. Using a combination of reshape2 and plyr (I'm using R to run sqlite), it took about 1,040 seconds. You mileage may vary, however.
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