将动态行转置为列

Question

I have two tables: one is programs and the other one is bookprograms . The programs table is where you get the program name. The rows in this table can be added or edited.

I used the query below but it doesn't reflect if there is a new program:

SELECT  MAX(IF(programs = 'cla', title, NULL)) cla,
    MAX(IF(programs = 'csm', title, NULL)) csm
FROM    bookprograms
GROUP BY title

The structure of the first table.

╦════════════╦═════════════╗
║ ID         ║   Programs  ║
╬════════════╬═════════════╣
║ 1          ║     cla     ║
║ 2          ║     csm     ║
╩════════════╩═════════════╝

The second table is where I store the books and the program that corresponds to it.

╦════════════╦═════════════╗
║ Title      ║   Programs  ║
╬════════════╬═════════════╣
║ title1     ║     cla     ║
║ title2     ║     csm     ║
║ title3     ║     cla     ║
╩════════════╩═════════════╝

How would I come up with this result?

╦════════════╦═════════════╗
║ cla        ║   csm       ║
╬════════════╬═════════════╣
║ title1     ║   title     ║
║ title3     ║             ║
╩════════════╩═════════════╝

Answer 1

This query returns the data you need but not quite in the format you want it:

SELECT programs, GROUP_CONCAT(title) AS titles
FROM bookprograms
GROUP BY programs

It returns:

 programs | titles
----------+---------------
 cla      | title1,title3
 cls      | title2

In the client code you can morph this into the structure you need. The value of the header cell is returned in field programs . Split the value of field title by comma ( , ) and you have the data cells for the rest of the column. Repeat for each row from the result set to get all the columns of your desired table.