Question

I have 3 tables: table1, table2 & table3

I make a select query from table1 which LEFT JOINS the other two tables. In the select I have a group_concat which takes a value from table3. Everything works well until a row with a specific row doesn’t exist. The group_concat list becomes empty. Instead, I would like it to set values in the group_concat to NULL for the ones where the rows doesn’t exist.

Like I said if the value in table3 exist for all the rows in table2 then it works. If not, the whole group_concat is empty.

Some “simplified” code of what I got so far:

SELECT 
    table1.table2Id,
    table1.dateAdded,

IF(COUNT(table2.table3Id) = COUNT(*), GROUP_CONCAT(table2.table3Id), NULL) as group1,
IF(COUNT(table3.ext) = COUNT(*), GROUP_CONCAT(table3.ext), NULL) as group2
FROM table1
LEFT JOIN table2 ON
    table2.id = table1.table2Id
LEFT JOIN table3 ON
    table3.id = table2.table3Id

Answer 1

Fixed it by changing

IF(COUNT(table3.ext) = COUNT(*), GROUP_CONCAT(table3.ext), NULL) as group2

to

GROUP_CONCAT(IFNULL(table3.ext, NULL)) as group2