The most efficient want to check the presence of a row, use the count():select count(1) from yourTableName where yourCondition;Let us first create a table:mysql> create table DemoTable (    Id int,    FirstName varchar(20) ); Query OK, 0 rows affected (0.73 sec)Following is the query to insert some records in the table using insert command:mysql> insert into DemoTable values(100, 'Larry'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(110, 'Sam'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(120, 'Mike'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(130, 'Carol'); Query ... Read More

To turn ON the general log, you need to use SET command. Following is the syntax −set global general_log=ON;Let us check the general log status with the help of SHOW command −mysql> SHOW variables like '%general_log%';This will produce the following output −+------------------+---------------------+ | Variable_name | Value | +------------------+---------------------+ | general_log | OFF | | general_log_file | DESKTOP-QN2RB3H.log | +------------------+---------------------+ 2 rows in set ... Read More

First of all, you need to check the host. The host can be ‘localhost’ or ‘%’. Check the existence of user accounts with host −mysql> select user, host from MySQL.user;This will produce the following output −+------------------+-----------+ | user             | host      | +------------------+-----------+ | Bob              | % | | User2            | % | | mysql.infoschema | % | ... Read More

To calculate age from date of birth, you can use the below syntax −select timestampdiff(YEAR, yourColumnName, now()) AS anyAliasName from yourTableName;Let us first create a table −mysql> create table DemoTable (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentDOB datetime ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentDOB) values('1996-01-12'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(StudentDOB) values('1990-12-31'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(StudentDOB) values('1989-04-01'); Query OK, 1 row affected (0.45 sec) mysql> insert into DemoTable(StudentDOB) values('2000-06-17'); Query ... Read More

To count null values in MySQL, you can use CASE statement. Let us first see an example and create a table −mysql> create table DemoTable (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    FirstName varchar(20) ); Query OK, 0 rows affected (0.77 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(FirstName) values('John'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(FirstName) values(null); Query OK, 1 row affected (0.25 sec) mysql> insert into DemoTable(FirstName) values(''); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(FirstName) values('Larry'); Query OK, 1 row affected (0.17 ... Read More

To skip blank and null in MySQL, use the following syntax:select *from yourTableName where yourColumnName IS NOT NULL AND yourColumnName '';Let us first create a table:mysql> create table DemoTable (Id int, FirstName varchar(20)); Query OK, 0 rows affected (0.66 sec)Following is the query to insert records in the table using insert command:mysql> insert into DemoTable values(100, 'Larry'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(101, ''); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(102, 'Chris'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(103, null); Query OK, 1 ... Read More

Yes, we can select second largest record from a table without using LIMIT clause. Let us first see an example and create a table −mysql> create table DemoTable (    Number int ); Query OK, 0 rows affected (0.66 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(78); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(67); Query OK, 1 row affected (0.25 sec) mysql> insert into DemoTable values(92); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(98); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(88); ... Read More

For this, you can use INFORMATION_SCHEMA.COLUMNS as shown in the following syntax −SELECT *FROM (SELECT *FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME= 'yourTableName') anyAliasName;Let us first create a table:mysql> create table DemoTable (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentFirstName varchar(20),    StudentLastName varchar(20),    StudentAge int ); Query OK, 0 rows affected (1.51 sec)Here is the query to use `SHOW COLUMNS` as a valid data source −mysql> SELECT *FROM (SELECT *FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME= 'DemoTable')tbl;This will produce the following output −+---------------+--------------+-------------+------------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+---------------+--------------------+--------------------+-----------------+-------------+------------+----------------+---------------------------------+----------------+-----------------------+--------+ | TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME       | ORDINAL_POSITION | COLUMN_DEFAULT | IS_NULLABLE | ... Read More

You can use LEFT() from MySQL to display some character from the entire value in MySQL. Following is the syntax:select left(yourColumnName ,200 ) AS anyAliasName from yourTableName;Let us first create a table:mysql> create table DemoTable (Paragraph longtext); Query OK, 0 rows affected (0.71 sec)Following is the query to insert records in the table using insert command:mysql> insert into DemoTable values('Introduction to Java, Introduction to C, Introduction to C++, Introduction to Spring, Introduction to Hibernate, Introduction to Python, Introduction to MySQL, Introduction to MongoDB, Introduction to SQL Server, Introduction to ASP.net, Introduction to JSF'); Query OK, 1 row affected (0.13 sec)Following ... Read More

Yes, you can find out the next auto_increment with SELECT AUTO_INCREMENT as shown in the below syntax −SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA= yourDatabaseName AND TABLE_NAME=yourTableName;Let us first create a table −mysql> create table DemoTable (    ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    ClientName varchar(20),    ClientAge int ); Query OK, 0 rows affected (1.33 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(ClientName, ClientAge) values('John', 23); Query OK, 1 row affected (0.35 sec) mysql> insert into DemoTable(ClientName, ClientAge) values('Carol', 21); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable(ClientName, ClientAge) values('Bob', ... Read More