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Update 'a' record with 'b' and 'b' with 'a' in a MySQL column (swap) with only 'a' and 'b' values?
For this, use a CASE statement. Let us first create a table −
mysql> create table DemoTable ( Value char(1) ); Query OK, 0 rows affected (1.21 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable values('a');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable values('b');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values('a');
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable values('a');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values('b');
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable values('a');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values('b');
Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement
mysql> select *from DemoTable;
This will produce the following output −
+-------+ | Value | +-------+ | a | | b | | a | | a | | b | | a | | b | +-------+ 7 rows in set (0.00 sec)
Following is the query to update 'a' record with 'b' and 'b' with 'a' −
mysql> update DemoTable set Value=case when Value='a' then 'b' else 'a' end; Query OK, 7 rows affected (0.17 sec) Rows matched: 7 Changed: 7 Warnings: 0
Let us check the table records once again −
mysql> select *from DemoTable;
This will produce the following output −
+-------+ | Value | +-------+ | b | | a | | b | | b | | a | | b | | a | +-------+ 7 rows in set (0.00 sec)
Updated on: 25-Sep-2019
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