Delete one row and reorder the others with the correct ID in MySQL?

MySQLMySQLi Database

To understand the concept, let us first create a table. The query to create a table is as follows

mysql> create table ReorderSortDemo
   -> (
   -> UserId int
   -> );
Query OK, 0 rows affected (0.57 sec)

Insert some records in the table using insert command. The query is as follows −

mysql> insert into ReorderSortDemo values(14);
Query OK, 1 row affected (0.13 sec)
mysql> insert into ReorderSortDemo values(4);
Query OK, 1 row affected (0.10 sec)
mysql> insert into ReorderSortDemo values(6);
Query OK, 1 row affected (0.11 sec)
mysql> insert into ReorderSortDemo values(3);
Query OK, 1 row affected (0.09 sec)
mysql> insert into ReorderSortDemo values(8);
Query OK, 1 row affected (0.11 sec)
mysql> insert into ReorderSortDemo values(18);
Query OK, 1 row affected (0.08 sec)
mysql> insert into ReorderSortDemo values(1);
Query OK, 1 row affected (0.12 sec)
mysql> insert into ReorderSortDemo values(11);
Query OK, 1 row affected (0.08 sec)
mysql> insert into ReorderSortDemo values(16);
Query OK, 1 row affected (0.09 sec)

Display all records from the table using select statement. The query is as follows −

mysql> select *from ReorderSortDemo;

The following is the output

+--------+
| UserId |
+--------+
|     14 |
|      4 |
|      6 |
|      3 |
|      8 |
|     18 |
|      1 |
|     11 |
|     16 |
+--------+
9 rows in set (0.00 sec)

First delete one row from the table then use update command to reorder the others. The query is as follows −

mysql> delete from ReorderSortDemo where UserId=8;
Query OK, 1 row affected (0.20 sec)

After deleting, let us check the table records once again. The query is as follows −

mysql> select *from ReorderSortDemo;

The output is as follows

+--------+
| UserId |
+--------+
|     14 |
|      4 |
|      6 |
|      3 |
|     18 |
|      1 |
|     11 |
|     16 |
+--------+
8 rows in set (0.00 sec)

Here is the query to reorder the other columns

mysql> update ReorderSortDemo
   -> set UserId=UserId-1
   -> where UserId > 8;
Query OK, 4 rows affected (0.22 sec)
Rows matched: 4 Changed: 4 Warnings: 0

Let us check the table records once again. The query is as follows −

mysql> select *from ReorderSortDemo;

The output is as follows

+--------+
| UserId |
+--------+
|     13 |
|      4 |
|      6 |
|      3 |
|     17 |
|      1 |
|     10 |
|     15 |
+--------+
8 rows in set (0.00 sec)
raja
Published on 01-Apr-2019 09:30:33
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