Which datatype should I use for flag in MySQL?

To set a flag, you can set the type as tinyint(1) type.

 Following is the syntax −

yourColumnName tinyint(1) DEFAULT 1;

Let us first create a table −

mysql> create table DemoTable (    ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    ClientName varchar(20),    isMarried tinyint(1) DEFAULT 1 ); Query OK, 0 rows affected (0.64 sec)

Insert some records in the table using insert command −

mysql> INSERT INTO DemoTable(ClientName,isMarried) values('Larry',0); Query OK, 1 row affected (0.16 sec) mysql> INSERT INTO DemoTable(ClientName) values('David'); Query OK, 1 row affected (0.12 sec) mysql> INSERT INTO DemoTable(ClientName,isMarried) values('Mike',1); Query OK, 1 row affected (0.19 sec) mysql> INSERT INTO DemoTable(ClientName) values('Carol'); Query OK, 1 row affected (0.14 sec)

Following is the query to display all records from the table using select statement −

mysql> select *from DemoTable;

This will produce the following output that displays one of the column, which is set as flag −

+----------+------------+-----------+ | ClientId | ClientName | isMarried | +----------+------------+-----------+ | 1        | Larry      | 0         | | 2        | David      | 1       | | 3        | Mike       | 1 | | 4        | Carol      | 1 | +----------+------------+-----------+ 4 rows in set (0.00 sec)