Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
Articles on Trending Technologies
Technical articles with clear explanations and examples
Sum columns corresponding values according to similar dates in MySQL?
For this, use aggregate function SUM() along with GROUP BY. Let us first create a table −mysql> create table DemoTable1522 -> ( -> ProductPurchaseDate date, -> NumberOfProduct int -> ); Query OK, 0 rows affected (1.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1522 values('2019-01-21', 45); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1522 values('2018-12-31', 78); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1522 values('2019-01-21', 67); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1522 values('2019-03-01', 56); Query OK, 1 row affected (0.19 ...
Read MoreConvert Class in C#
The Convert Class has methods to convert a base data type to another base data type. Let us see some examples −The Convert.ToBoolean() method in C# is used to convert a specified value to an equivalent Boolean value.SyntaxFollowing is the syntax −public static bool ToBoolean (string val, IFormatProvider provider);Above, Val is a string that contains the value of either TrueString or FalseString, whereas the provider is an object that supplies culture-specific formatting information.ExampleLet us now see an example to implement the Convert.ToBoolean() method − Live Demousing System; using System.Globalization; public class Demo { public static void Main(){ ...
Read MoreUpdate a column in MySQL and remove the trailing underscore values
To remove the trailing values, use TRIM() as in the below update syntax −update yourTableName set yourColumnName=trim(trailing '_' from yourColumnName);Let us first create a table −mysql> create table DemoTable1521 -> ( -> StudentCode varchar(20) -> ); Query OK, 0 rows affected (1.33 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1521 values('345_'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable1521 values('12345'); Query OK, 1 row affected (0.38 sec) mysql> insert into DemoTable1521 values('9084_'); Query OK, 1 row affected (1.29 sec)Display all records from the table using select statement −mysql> select ...
Read MoreChar Struct in C#
The Char Struct in C# represents a character as a UTF-16 code unit. Here are some of the methods −MethodDescriptionConvertToUtf32(Char, Char)Converts the value of a UTF-16 encoded surrogate pair into a Unicode code point.ConvertToUtf32(String, Int32)Converts the value of a UTF-16 encoded character or surrogate pair at a specified position in a string into a Unicode code point.Equals(Char)Returns a value that indicates whether this instance is equal to the specified Char object.Equals(Object)Returns a value that indicates whether this instance is equal to a specified object.GetHashCode()Returns the hash code for this instance.GetNumericValue(Char)Converts the specified numeric Unicode character to a double-precision floating-point number.IsDigit(String, ...
Read MoreHow do I select data from one table only where column values from that table match the column values of another table in MySQL?
For this, you can use subquery along with EXISTS. Let us first create a table −mysql> create table DemoTable1 -> ( -> Id int, -> SubjectName varchar(20) -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values(111, 'MySQL'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1 values(112, 'MongoDB'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1 values(113, 'Java'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1 values(114, 'C'); Query OK, 1 row affected (0.27 sec) ...
Read MoreMySQL query to select rows one batch at a time
For this, you can use the concept of LIMIT and OFFSET. Let us first create a table −mysql> create table DemoTable1514 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> FirstName varchar(20) -> ); Query OK, 0 rows affected (0.63 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1514(FirstName) values('Chris'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1514(FirstName) values('Bob'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1514(FirstName) values('Sam'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable1514(FirstName) values('Mike'); Query OK, 1 row ...
Read MoreWhen inserting a new row, should I include the columns that are null in the MySQL query?
If you do not specify the column list in insert statement then you can use below syntax −insert into yourTableName values(NULL, yourValue, NULL, NULL, .....N);Let us first create a table −mysql> create table DemoTable1513 -> ( -> StudentId int, -> StudentName varchar(20) , -> StudentAge int, -> StudentCountryName varchar(20) -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1513 values(NULL, 'Chris Brown', NULL, NULL); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1513 values(101, NULL, NULL, NULL); Query OK, 1 row ...
Read MoreHow do I detect if the ON UPDATE event fired with query in MySQL?
You can detect with the help of row_count(). If the row_count() returns 1 that means it is a new record. If it returns 2, that means the ON UPDATE event is fired with query. Following is the syntax −select row_count();Let us first create a table −mysql> create table DemoTable1512 -> ( -> Value int , -> UNIQUE(Value) -> ); Query OK, 0 rows affected (0.60 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1512 values(90) on duplicate key update Value=Value+10; Query OK, 1 row affected (0.09 sec)Now you can check the on ...
Read MoreHow to prevent MySQL GROUP BY from collapsing NULL values into a single row?
Fir this, you can use IFNULL() along with ORDER BY clause. Let us first create a table table −mysql> create table DemoTable1511 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> FirstName varchar(20) -> ); Query OK, 0 rows affected (1.97 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1511(FirstName) values('John'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable1511(FirstName) values('Robert'); Query OK, 1 row affected (0.29 sec) mysql> insert into DemoTable1511(FirstName) values('Mike'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1511(FirstName) values('Robert'); Query OK, 1 ...
Read MoreMySQL update datetime column values and add 10 years 3 months 22 days and 10 hours, 30 minutes to existing data?
For this, you can use INTERVAL in MySQL. Let us first create a table −mysql> create table DemoTable1509 -> ( -> ArrivalTime datetime -> ); Query OK, 0 rows affected (0.51 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1509 values('2018-01-21 10:20:30'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1509 values('2019-04-01 11:00:00'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1509 values('2015-12-12 05:45:20'); Query OK, 1 row affected (0.15 sec)Display all records from the table using select statement −mysql> select * from DemoTable1509;This will produce the following output ...
Read More