ORDER BY ASC with Nulls at the Bottom

Question

I\'m writing an SQL query that connects a schools table to a districts table. Simple One-To-Many relationship where each school is attached to one district. My query is as

Answer 1

Only 1 minute after asking the question I found my answer. In the order by clause use case to make nulls have a higher value than anything else:

 ORDER BY (CASE WHEN districts.id IS NULL then 1 ELSE 0 END),districts.name, schools.name;

Answer 2

Nulls by default occur at the top, but you can use IsNull to assign default values, that will put it in the position you require...

SELECT schools.id AS schoolid,schools.name AS school, districts.id AS districtid, districts.name AS district FROM sms_schools AS schools LEFT JOIN sms_districts AS districts ON schools.districtid = districts.id WHERE 1 = 1 
ORDER BY isnull(districts.name,'1'), schools.name 

Answer 3

You could use the ISNULL() function.

From the MySQL manual:

ISNULL(expr)

If expr is NULL, ISNULL() returns 1, otherwise it returns 0.

For example:

ORDER BY ISNULL(districts.name), districts.name, schools.name

I like to use this instead of the CASE option for MySQL. Just be aware that it's not portable since ISNULL() is not standard SQL and functions differently in other versions of SQL.

Answer 4

SELECT
 schools.id AS schoolid,
 schools.name AS school,
 districts.id AS districtid,
 districts.name AS district,
 if(schools.districtid IS NULL,1,0) as sort 
FROM sms_schools AS schools
LEFT JOIN sms_districts AS districts 
 ON schools.districtid = districts.id
WHERE 1 = 1
ORDER BY sort, districts.name, schools.name

put any more sort rules insite the 'new' colunm and use any number hide the field in your code, test if it is possebele to sort on the if dirctly(order by if...)

good luck