To get the length of all columns i.e. the count of all the characters for column values, use char_length(). Let us first create a table. Here, we have two columns, therefore we will calculate for each row consisting of both the values FirstName and LastName −mysql> create table DemoTable ( ... Read More

Following is the syntax −delete from yourTableName where yourColumnName < (yourAnotherDateValue - INTERVAL 30 DAY);Let us first create a table −mysql> create table DemoTable (    DueDate date ); Query OK, 0 rows affected (0.68 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2019-08-25'); Query ... Read More

For this, use CONCAT() method in MySQL. Let us first create a table −mysql> create table DemoTable (    FirstName varchar(50),    LastName varchar(50) ); Query OK, 0 rows affected (0.63 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 'Brown'); Query OK, 1 row ... Read More

To alter column type of multiple columns in a single MySQL query, the syntax is as follows −alter table yourTableName modify column yourColumnName 1 yourDataType1, modify column yourColumnName 2 yourDataType2, . . N;Let us first create a table −mysql> create table DemoTable (    Id varchar(100),    FirstName text,   ... Read More

For this, you can use the CASE statement along with SUM(). Here, we will be finding the count of Male and Female records from a column with employee gender values. Let us first create a table −mysql> create table DemoTable (    EmployeeGender ENUM('Male', 'Female') ); Query OK, 0 rows ... Read More

The @ symbol in a stored procedure can be used for user-defined session variables. Let us first create a table −mysql> create table DemoTable (    StudentName varchar(50) ); Query OK, 0 rows affected (1.30 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John Smith'); ... Read More

Let us first create a table −mysql> create table DemoTable (    FirstName varchar(100),    LastName varchar(100) ); Query OK, 0 rows affected (0.83 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Adam', 'Smith'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable ... Read More

For this, you can use the property IS NULL for null values in MySQL. Let us first create a table −mysql> create table DemoTable (    Name varchar(100) ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Robert'); Query ... Read More

Let us first create a table −mysql> create table DemoTable (    Id int,    ColorName varchar(100) ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 'Red'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable ... Read More

Let us first create a table. Here, we have VARCHAR type for value −mysql> create table DemoTable (    Value varchar(100) ); Query OK, 0 rows affected (1.80 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('100'); Query OK, 1 row affected (0.20 sec) mysql> ... Read More