SQLite and custom order by
I have a table with categories:
ID Category
"1","Baking"
"3","Family"
"4","Entertaining"
"5","Children"
"6","Desserts"
Now I would like to order the result of the select statement to
ID Category
"4","Entertaining"
"3","Family"
"1","Baking"
"5","Children"
"6","Desserts"
for example. In MySQL, you'd do it like this:
SELECT * FROM CATEGORIES ORDER BY FIELD (ID, 4,3,1,5,6);
How would you 开发者_开发技巧do it in SQLite though? I don't have an "order by" field.
ORDER BY
CASE ID
WHEN 4 THEN 0
WHEN 3 THEN 1
WHEN 1 THEN 2
WHEN 5 THEN 3
WHEN 6 THEN 4
END
A second way of doing it (the first one being with CASE WHEN ... THEN END
as already stated in other answers) is:
ORDER BY ID=4 DESC,
ID=3 DESC,
ID=1 DESC,
ID=5 DESC,
ID=6 DESC
I don't have an "order by" field
Why not?
If it is because the sort order is application sepcific then do the sort in the application rather than in the database.
If it is because the sort order is specific to just this one query then encode it in the query HOWEVER I strongly suggest you make this transparent to the calling application e.g. (Standard SQL syntax):
SELECT T2.ID, T2.Category,
T2.query_name_here_sort_order
FROM (
SELECT T1.ID, T1.Category,
CASE ID
WHEN 4 THEN 1
WHEN 3 THEN 2
WHEN 1 THEN 3
WHEN 5 THEN 4
WHEN 6 THEN 5
END AS query_name_here_sort_order
FROM CATEGORIES AS T1
) AS T2 (
ID, Category,
query_name_here_sort_order
)
ORDER
BY query_name_here_sort_order;
If the sort order is used by multiple queries and/or applications then add it to a column in a table in the database then use that column in your query.
精彩评论