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Articles on Trending Technologies
Technical articles with clear explanations and examples
Open MySQL root access from all hosts?
To open root access from all hosts, we need to change the database to “mysql” with the help of USE command. The syntax of USE command is as follows − USE anyDatabasename; Now, I will use predefined database ‘mysql’, which is as follows − mysql> use mysql; Database changed I have changed the database above. Here is the query to get root access from the entire host − mysql> UPDATE user set host='%' where host='localhost'; Query OK, 6 rows affected (0.19 sec) Rows matched: 6 Changed: 6 Warnings: 0
Read MoreComparison of Java and .NET
Java is a high-level programming language originally developed by Sun Microsystems and released in 1995. Java runs on a variety of platforms, such as Windows, Mac OS, and the various versions of UNIX. .NET framework is a computer software framework invented by Microsoft. It runs on Microsoft Windows OS (Operating Systems). It provides user interface, data access, database connectivity, cryptography, web application development, etc. Languages Java supports only Java patterns. .NET supports multiple languages such as VB.NET, C#, F#, etc. Platforms Java is platform independent and it can run on Windows, Linux and Mac OS. .NET works on Windows. Runtime ...
Read MoreError 1046 No database Selected, how to resolve?
The 1046 error occurs if you forget to select any database before creating a table. Let us see how and why this error occurs. We will try to create a table without selecting a database − mysql> CREATE table MyTable1 -> ( -> id int -> ); ERROR 1046 (3D000): No database selected Or mysql> INSERT into sample values(1); ERROR 1046 (3D000): No database selected Look at the output above, we are getting the same 1046 error: “No database selected” Now, we can resolve this error after selecting any ...
Read MoreHow to set NOW() as default value for datetime datatype in MySQL?
We can set the now() function as a default value with the help of dynamic default. First, we will create a table with data type” datetime”. After that, we will set now() as the default value for column “MyTime” as shown below. Creating a table. mysql> create table DefaultDateTimeDemo -> ( -> MyTime datetime default CURRENT_TIMESTAMP -> ); Query OK, 0 rows affected (0.59 sec) After creating the above table, we won’t insert any value while using the insert command. This is done so that we can get the ...
Read MoreHow to get the count of each distinct value in a column in MySQL?
Let us see an example to get the count of each distinct value in a column. Firstly, we will create a table. The CREATE command is used to create a table. mysql> create table DistinctDemo1 - > ( - > id int, - > name varchar(100) - > ); Query OK, 0 rows affected (0.43 sec) Inserting records mysql> insert into DistinctDemo1 values(1, 'John'); Query OK, 1 row affected (0.34 sec) mysql> insert into DistinctDemo1 values(2, 'John'); Query OK, 1 row affected (0.20 sec) ...
Read MoreInstruction Type LXI rp, d16 in 8085 Microprocessor
In the 8085 Instruction set there are four instructions, which belong to the type LXI rp, d16. These instructions are used to load the 16-bit address into the register pair. We can use this instruction to load data from memory location using the memory address, which is stored in the register pair rp. For an example, if the instruction is LXI H, FE50. It means that the FE50 is loaded into the HL register pair. The rp can be BC, DE, HL or SP. The LXI instructions and their Hex-codes are as follows. Mnemonics, Operand Opcode (in HEX) ...
Read MoreShortcomings of mysql_real_escape_string?
The shortcoming of mysql_real_escape_string is as follows − It has main shortcoming in the modern API while we are making prepared statement. This has another shortcoming for every possible attack when you will typecast. Let us see the typecast syntax in MySQL − (TypeCast)mysql_real_escape_string($_REQUEST['anyColumnName'])); In the above syntax, we are typecasting, but in this case, it is not safer for every possible attack. The other cases include the following − It is not type safe. It is not for injection attack.
Read MoreBest data type for storing currency values in a MySQL database?
For representation of money, we need to use Decimal (TotalDigitsinteger, DigitsAfterDecimalinteger) method. Let’s say, we need to display the value 345.66. For that, count how many digits are available. In value 345.66, there are 5 digits in total and 2 digits after decimal point, which is 66. We can represent the same with the help of Decimal() method from MySQL. Here is the exact representation. DECIMAL(5, 2) Let us first create a table and consider the same above representation for our example − mysql> create table MoneyRepresentation -> ( -> Money ...
Read MoreALTER TABLE to add a composite primary key in MySQL?
To add composite primary key, use the ALTER command. Let us first create a demo table The query to create a table. mysql> create table CompositePrimaryKey -> ( -> Id int, -> StudentName varchar(100), -> Age int -> ); Query OK, 0 rows affected (0.56 sec) Haven’t added composite primary key above till now. Let us now check with the help of desc command. mysql> desc CompositePrimaryKey; The following is the output. +-------------+--------------+------+-----+---------+-------+ | Field ...
Read MoreUsing DISTINCT and COUNT together in a MySQL Query?
We can use DISTINCT and COUNT together in a single MySQL query. Firstly, let us create a table. The CREATE command is used to create a table. mysql> create table DistCountDemo - > ( - > id int, - > name varchar(100), - > age int - > ); Query OK, 0 rows affected (0.48 sec) Records are inserted with the help of INSERT command. mysql> insert into DistCountDemo values(1, 'John', 23); Query OK, 1 row affected (0.11 sec) mysql> insert ...
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