I have tried mysql ststement for dinamically rows to column by followed here with query statement:
SET @sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(
'MAX(CASE WHEN col = ''',
col,
''' THEN val END) as `',
col, '`'
)
)INTO @sql
FROM
(
SELECT A.id_a, D.id_c id_c,
C.students students,
CONCAT(B.`code`, '_', A.id_a) col,
CONCAT(D.value_m, ',', D.value_n) val
FROM table_a A
INNER JOIN table_d D ON A.id_a =D.id_a
INNER JOIN table_b B ON D.id_b=B.id_b
INNER JOIN table_c C ON D.id_c=C.id_c
)dd;
SET @sql = CONCAT('SELECT id_c, students,', @sql, '
FROM(
SELECT A.id_a, D.id_c id_c,
C.students students,
CONCAT(B.`code`, '_', A.id_a) col,
CONCAT(D.value_m, ',', D.value_n) val
FROM table_a A
INNER JOIN table_d D ON A.id_a =D.id_a
INNER JOIN table_b B ON D.id_b=B.id_b
INNER JOIN table_c C ON D.id_c=C.id_c
)dd
GROUP BY id_c'
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
with result message:
Query OK, 0 rows affected
Query OK, 1 row affected
1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '', A.id_a) col,
CONCAT(D.value_m, ',', D.value_n) val
FROM table_a A ' at line 1
1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'MAX(CASE WHEN col = 'MAT_1' THEN val END) as `MAT_1`,MAX(CASE WHEN col = 'BIO_1'' at line 1
1243 - Unknown prepared statement handler (stmt) given to EXECUTE
1243 - Unknown prepared statement handler (stmt) given to DEALLOCATE PREPARE
I'm not familiar with sql statement like this, and what's wrong with that SQL QUERY
Thanks...
If you look at your code (and zoom in):
SET @sql = CONCAT('SELECT id_c, students,', @sql, '
[..]
CONCAT(B.`code`, '_', A.id_a) col,
CONCAT(D.value_m, ',', D.value_n) val
[..]
GROUP BY id_c'
);
you will see that _ and , are black, while they should be red as part of the string. That means your string ist "broken" there. So you need to escape the single quotes with '':
SET @sql = CONCAT('SELECT id_c, students,', @sql, '
[..]
CONCAT(B.`code`, ''_'', A.id_a) col,
CONCAT(D.value_m, '','', D.value_n) val
[..]
GROUP BY id_c'
);
Or use double quotes for strings that contain single quotes:
SET @sql = CONCAT('SELECT id_c, students,', @sql, "
[..]
CONCAT(B.`code`, '_', A.id_a) col,
CONCAT(D.value_m, ',', D.value_n) val
[..]
GROUP BY id_c"
);
Now the complete string is red as it should be :-)