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Is there a way in MySQL to reverse a boolean field with a single query?
Yes, you can use if() function from MySQL to reverse a boolean field. The syntax is as follows −
UPDATE yourTableName SET yourBooleanColumnName = IF(yourBooleanColumnName,0,1);
To understand the above syntax, let us create a table. The query to create a table is as follows −
mysql> create table ReverseBooleanField -> ( -> Id int NOT NULL AUTO_INCREMENT, -> isValid BOOLEAN -> , -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.56 sec)
Now you can insert some records in the table using insert command. The query is as follows −
mysql> insert into ReverseBooleanField(isValid) values(true); Query OK, 1 row affected (0.18 sec) mysql> insert into ReverseBooleanField(isValid) values(false); Query OK, 1 row affected (0.14 sec) mysql> insert into ReverseBooleanField(isValid) values(true); Query OK, 1 row affected (0.29 sec) mysql> insert into ReverseBooleanField(isValid) values(true); Query OK, 1 row affected (0.09 sec) mysql> insert into ReverseBooleanField(isValid) values(false); Query OK, 1 row affected (0.14 sec)
Display all records from the table using a select statement. The query is as follows −
mysql> select *from ReverseBooleanField;
The following is the output −
+----+---------+ | Id | isValid | +----+---------+ | 1 | 1 | | 2 | 0 | | 3 | 1 | | 4 | 1 | | 5 | 0 | +----+---------+ 5 rows in set (0.00 sec)
MySQL internally converts BOOLEAN to TINYINT(1) which gives true as 1 and false as 0.
Now, let us reverse boolean field in a single query −
mysql> update ReverseBooleanField set isValid = if(isValid,0,1); Query OK, 5 rows affected (0.21 sec) Rows matched − 5 Changed − 5 Warnings − 0
Check whether the boolean field is reversed or not using select statement. The query is as follows −
mysql> select *from ReverseBooleanField;
The following is the output −
+----+---------+ | Id | isValid | +----+---------+ | 1 | 0 | | 2 | 1 | | 3 | 0 | | 4 | 0 | | 5 | 1 | +----+---------+ 5 rows in set (0.00 sec)
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