Define with NOT NULL, if a column must not be empty. Let us first create a table with one of the columns as NOT NULL −mysql> create table DemoTable1895    (    Id int NOT NULL,    FirstName varchar(20),    LastName varchar(20) NOT NULL    ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1895 values(100, 'John', 'Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1895 values(NULL, 'Chris', 'Brown'); ERROR 1048 (23000): Column 'Id' cannot be null mysql> insert into DemoTable1895 values(102, 'Carol', NULL); ERROR 1048 (23000): ... Read More

For this, use unix_timestamp(). Let us first create a table −mysql> create table DemoTable1894    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    DueTime int    ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1894 values(); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1894 values(); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1894 values(); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1894;This will produce the following output −+----+---------+ | ... Read More

In this program, we will connect to a MySQL database and insert a null value into a table using Java's JDBC API. We will use the PreparedStatement class along with the setNull() method to achieve this. After the value is inserted, you can check the table to see how the null value is reflected. Steps to insert null value into a MySQL database Following are the steps to insert null value into a MySQL database − Establish a connection to the MySQL database using the DriverManager.getConnection() method. Define the SQL query that ... Read More

Yes, we can do regex match in a select statement −select yourColumnName from yourTableName where yourColumnName regexp '^yourValue';Let us first create a table −mysql> create table DemoTable1892    (    FirstName varchar(20)    ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1892 values('John'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1892 values('Adam'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1892 values('Jace'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1892 values('Johny'); Query OK, 1 row affected (0.00 sec) mysql> insert into ... Read More

Let us first create a stored procedure −mysql> delimiter // mysql> create procedure declare_demo_sp()    begin    declare Value1 int;    declare Value2 int;    set Value1=100;    set Value2=2000;    select Value1,Value2,Value1*Value2 as MultiplicationResult;    end    // Query OK, 0 rows affected (0.00 sec) mysql> delimiter ;Call a stored procedure using CALL command −mysql> call declare_demo_sp();This will produce the following output −+--------+--------+----------------------+ | Value1 | Value2 | MultiplicationResult | +--------+--------+----------------------+ |    100 |   2000 |               200000 | +--------+--------+----------------------+ 1 row in set (0.00 sec) Query OK, 0 rows affected (0.00 sec)

For this, use INSERT ON DUPLICATE KEY UPDATE command. Let us first create a table −mysql> create table DemoTable1891    (    FirstName varchar(20),    UNIQUE KEY(FirstName)    ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1891 values('Chris') on duplicate key update  FirstName='Robert'; Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1891 values('David') on duplicate key update  FirstName='Robert'; Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1891 values('Chris') on duplicate key update  FirstName='Robert'; Query OK, 2 rows affected (0.00 sec)Display all records from the table ... Read More

For this, use IF(). Let us first see the current date −mysql> select curdate(); +------------+ | curdate()  | +------------+ | 2019-12-10 | +------------+ 1 row in set (0.00 sec)Let us first create a table −mysql> create table DemoTable1890    (    DueDate timestamp    ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1890 values('2017-12-10'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1890 values('2021-12-10'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1890 values('2018-04-24'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1890 ... Read More

To sum current month records, use the SUM() and MONTH() function. Let us first create a table −mysql> create table DemoTable1889    (    DueDate date,    Amount int    ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1889 values('2019-12-11', 500); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1889 values('2019-11-11', 1000); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1889 values('2018-12-04', 700); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1889 values('2017-12-10', 300); Query OK, 1 row affected (0.00 sec)Display all records ... Read More

For this, you can use MD5(). Let us first create a table −mysql> create table DemoTable1887    (    Password text,    HashPassword text    ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1887(Password) values('John@9089'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1887(Password) values('90987_Carol'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1887(Password) values('656464_David_4343'); Query OK, 1 row affected (0.00 sec)Display some records in the table using insert command −mysql> select * from  DemoTable1887;This will produce the following output −+-------------------+--------------+ | Password     ... Read More

To get whether a column is a primary key, use COLUMN_NAME and COLUMN_KEY='PRI'. With that, the entire syntax is as follows −select column_name, case when column_key= 'PRI' then 'yourMessage1' else ''yourMessage2' end as anyAliasName from information_schema.columns where table_schema =database() and `table_name` = yourTableName order by `table_name`, ordinal_position;To understand the above syntax, let us create a table −mysql> create table DemoTable1886    (    Id int NOT NULL,    FirstName varchar(20),    LastName varchar(20),    Age int,    DateOfBirth datetime,    Education varchar(40),    PRIMARY KEY(Id)    ); Query OK, 0 rows affected (0.00 sec)Here is the query to get whether ... Read More