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To count the number of occurrences of a string in a VARCHAR, we can use the logic of subtraction with length. First, we will create a table with the help of create command. mysql> create table StringOccurrenceDemo -> ( -> Cases varchar(100), -> StringValue varchar(500) -> ); Query OK, 0 rows affected (0.56 sec) After executing the above table, we will insert records into the table. The query is as follows − mysql> insert into StringOccurrenceDemo values('First', 'This is MySQL Demo and MySQL is ... Read More
Homeschooling has changed the conventional schooling system across the globe. The flexibility of the curriculum, individual schedule, and personalized syllabus is catching up all over the world and many countries are recognizing the value of homeschooling. In the last decade, the well-informed parents in India have started opting for homeschooling or alternative schooling, although a majority of Indian parents still prefer conventional education. There is one very important reason in India why parents are still opting for conventional education more than homeschooling. The laws in India, especially the Right to education act makes it mandatory for every child from ... Read More
There are five main memory areas which are used to various Java elements. Following is the list of the same. Class Area - This area contains the static members of the class. Method Area - This area contains the method definition and executable code. Heap Area - This area contains the objects which are dynamically allocated/deallocated. if an object is no more referenced by any live reference it is deallocated. Stack Area - This area contains the local variables. Pool Area - Contains immutable objects like string.
Yes, primary key is automatically indexed in MySQL because primary key, index, etc gets stored into B-trees. All engines including InnoDB as well as MyISAM automatically supports the primary key to be indexed. The primary key is implicitly indexed in InnoDB, MyISAM, and other engines. Let us create a table with primary key − mysql> create table DemoIndex -> ( -> Id int not null, -> primary key(Id) -> ); Query OK, 0 rows affected (1.21 sec) In the above table, Id is implicitly indexed.
MySQLi is also known as MySQL improved Extension. It is a relational SQL database management system. It is often used inside PHP to provide an interface with the MySQL databases. Some of the reasons why MySQLi is famous are given below − MySQLi uses the standard form of the SQL language. MySQLi is free as it is released under an open source license. MySQLi can be easily used with PHP which is the most famous language for web development. MySQLi is a very powerful language and it can handle the functionality of powerful database packages. MySQLi can work with ... Read More
We cannot use a function for default value in MySQL, but we can use triggers. Let us see an example. First, we will create a table. The CREATE command is used to create a table. mysql> CREATE table TbLFunctionTrigger - > ( - > id int, - > username varchar(100) - > ); Query OK, 0 rows affected (0.55 sec) The following is the syntax to create a trigger and include a default value. CREATE TRIGGER anyName BEFORE INSERT ON yourTableName FOR EACH ROW ... Read More
It is very difficult to say whether to prefer one large table or multiple small tables. It depends − On the application we are using. On database normalization However, there are many key points, through which we can say that multiple small tables are good in that situation. Suppose many developers are going to develop multiple tables, then there is a need to split them into multiple small tables. A situation when you are giving authority to many developers. This authority is for different parts of data. In this case, a need arise to split into multiple small ... Read More
Let us now see the following methods to calculate the time difference between two timestamps in seconds. Method The following is the query to calculate the difference between two timestamps. mysql> SELECT TIMESTAMPDIFF(SECOND, '2018-10-17 11:51:55', '2018-10-17 11:51:58'); The following is the output in seconds. +---------------------------------------------------------------------+ | TIMESTAMPDIFF(SECOND, '2018-10-17 11:51:55', '2018-10-17 11:51:58') | +---------------------------------------------------------------------+ | ... Read More
MVI is a mnemonic, which actually means “Move Immediate”. With this instruction, we can load a register with an 8-bitsor 1-Bytevalue. This instruction supports immediate addressing mode for specifying the data in the instruction. In the instruction “d8” stands for any 8-bit data, and ‘r’ stands for any one of the registers e.g. A, B, C, D, E, H or L. So this r can replace any one of the seven registers. As ‘r’ can have any of the seven register names, so there are seven opcodes for this type of instruction. It occupies 2-Bytes in the memory. ... Read More
Both are engine types. Here is the query by which we can get to know which engine type and tables are being used. Firstly, we will choose the database with the help of USE command − mysql> USE business; Database changed Here is the query through which we can know which table or engine is being used − mysql> SHOW table status; The following is the output +------------------------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+--------------------+----------+----------------+---------+ |Name | Engine | Version | Row_format | ... Read More