是否有在 sql 表中的两条记录之间添加新记录的语法？

Question

Please suggest how to insert new record between two records. Id 3 of record/row is missed between id 2 and 4 in sql table.

Answer 1

SQL tables are unordered sets. You cannot add a record "between two records", because there is no order to the records. Even if your queries seem to return the rows in some order, it's completely arbitrary, and unless you have an explicit order by clause could very well change.

In other words - you should just insert the new row, and if you care about ordering by the id, always use order by id in your queries.

Answer 2

You could use a calendar table based approach here:

INSERT INTO yourTable (id)
SELECT t1.id
FROM
(
    SELECT 1 AS id UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL
    SELECT 4 UNION ALL SELECT 5
) t1
LEFT JOIN yourTable t2
    ON t2.id = t1.id
WHERE
    t1.id IS NULL;

In practice, you might replace the inlined subquery aliased as t1 above with a bona fide sequence table covering all id values which you would want to cover.