同じ値を持つすべての代替行文字列を更新するMySQLクエリ？

まずテーブルを作成しましょう-

mysql> create table DemoTable
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> Subject varchar(100)
   -> );
Query OK, 0 rows affected (0.76 sec)

挿入コマンド-

mysql> insert into DemoTable(Subject) values('C');
Query OK, 1 row affected (0.13 sec)

mysql> insert into DemoTable(Subject) values('MongoDB');
Query OK, 1 row affected (0.21 sec)

mysql> insert into DemoTable(Subject) values('Java');
Query OK, 1 row affected (0.18 sec)

mysql> insert into DemoTable(Subject) values('MongoDB');
Query OK, 1 row affected (0.12 sec)

mysql> insert into DemoTable(Subject) values('Python');
Query OK, 1 row affected (0.19 sec)

mysql> insert into DemoTable(Subject) values('MongoDB');
Query OK, 1 row affected (0.16 sec)

selectステートメントを使用してテーブルのすべてのレコードを表示する-

mysql> select *from DemoTable;

出力

+----+---------+
| Id | Subject |
+----+---------+
| 1  | C       |
| 2  | MongoDB |
| 3  | Java    |
| 4  | MongoDB |
| 5  | Python  |
| 6  | MongoDB |
+----+---------+
6 rows in set (0.00 sec)

これは、1行おきの文字列を更新するクエリです-

mysql> update DemoTable set Subject=replace(Subject,'MongoDB','MySQL') where Id%2=0;
Query OK, 3 rows affected (0.17 sec)
Rows matched: 3 Changed: 3 Warnings: 0

テーブルのすべてのレコードを確認しましょう-

mysql> select *from DemoTable;

出力

+----+---------+
| Id | Subject |
+----+---------+
| 1  | C       |
| 2  | MySQL   |
| 3  | Java    |
| 4  | MySQL   |
| 5  | Python  |
| 6  | MySQL   |
+----+---------+
6 rows in set (0.00 sec)