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Articles by Monica Mona
Page 2 of 7
How can we destroy a trigger?
We can destroy a trigger in two ways −Dropping a trigger explicitlyWith the help of the DROP statement, we can destroy a trigger explicitly. It can be understood with the help of the following example −mysql> DROP Trigger before_inser_studentage1; Query OK, 0 rows affected (0.05 sec)Dropping a trigger implicitlyA trigger will be destroyed implicitly if the table with which it is associated is destroyed or if the database which it is associated is destroyed.
Read MoreHow can I use MySQL subquery as a table in FROM clause?
We can use a subquery as a table in the FROM clause in the same way as the result of a subquery can be used with an operator in the WHERE clause. In the following example, we are using the result of subquery as a table by writing it after the FROM clause. It is mandatory to use an alias after subquery, here we are using alias ‘C_car’. To demonstrate it we are using the data as follows from table ‘Cars’ −mysql> Select * from Cars; +------+--------------+---------+ | ID | Name | Price | ...
Read MoreHow can I get the output based on comparison done with column’s name using MySQL IN() function?
In this scenario, we need to use the name of the column as ‘Expression’ which will then be compared with the values in the list. If a column has value/s matched within the list, the output would be produced. For understanding it, consider the example from employee table having the following data −mysql> Select * from Employee; +----+--------+--------+ | ID | Name | Salary | +----+--------+--------+ | 1 | Gaurav | 50000 | | 2 | Rahul | 20000 | | 3 | Advik | 25000 | | 4 | Aarav | 65000 | | 5 | Ram | 20000 | ...
Read MoreHow can we fetch a MySQL SET column as a list of integer offset?
We can fetch the MySQL SET column values as a list of integer offset with the help of the MAKE_SET() function. To make it understand, we are creating a table named ‘set_testing’ as follows −mysql> Create table set_testing( id INT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT, table SET('ABC', 'ABD', 'GHF') NOT NULL); Query OK, 0 rows affected (0.08 sec) mysql> Insert into set_testing (table) values('1'); Query OK, 1 row affected (0.06 sec) mysql> Insert into set_testing (table) values('2'); Query OK, 1 row affected (0.06 sec) mysql> Insert into set_testing (table) values('3'); Query OK, 1 row affected (0.02 ...
Read MoreWhat are the default rules used by the parser for parsing names of built-in functions?
Actually, when a parser encounters a word that is the name of a built-in function, it must determine whether the name represents a function call or is instead a non-expression reference to an identifier such as a table or column name. consider the following queries −1. Select sum(salary) from employee; 2. Create table sum (i int);In the first query SUM is a reference to a function call and in the second query, it is referencing to table name.Parser follows the following rules to distinguish whether their names are being used as function calls or as identifiers in non-reference context −Rule1 ...
Read MoreHow can we extract the Year and Month from a date in MySQL?
It can be done with the following three ways in MySQLBy using EXTRACT() function For extracting YEAR and MONTH collectively then we can use the EXTRACT function. We need to provide the YEAR_MONTH as an argument for this function. To understand it, consider the following function using the data from table ‘Collegedetail’ −mysql> Select EXTRACT(YEAR_MONTH From estb) from collegedetail; +-------------------------------+ | EXTRACT(YEAR_MONTH From estb) | +-------------------------------+ | 201005 | | 199510 | | ...
Read MoreWhat is the significant difference between MySQL TRUNCATE and DROP command?
The most significant difference between MySQL TRUNCATE and DROP command is that TRUNCATE command will not destroy table’s structure but in contrast DROP command will destroy table’s structure too.Examplemysql> Create table testing(id int PRIMARY KEY NOT NULL AUTO_INCREMENT, Name Varchar(20)); Query OK, 0 rows affected (0.24 sec) mysql> Insert into testing(Name) Values('Ram'), ('Mohan'), ('John'); Query OK, 3 rows affected (0.12 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> Select * from testing; +----+-------+ | id | Name | +----+-------+ | 1 | Ram | | 2 | Mohan | | 3 | John | +----+-------+ 3 rows ...
Read MoreHow to add columns to an existing MySQL table?
By using ALTER command we can add columns to an existing table.SyntaxAlter table table-name ADD (column-name datatype);Example In the example below, with the help of ALTER Command, column ‘GRADE’ is added to the table ‘Student’.mysql> Alter table Student ADD (Grade Varchar(10)); Query OK, 5 rows affected (1.05 sec) Records: 5 Duplicates: 0 Warnings: 0
Read MoreWhat is 'Space Complexity’?
Space ComplexitySpace complexity is an amount of memory used by the algorithm (including the input values of the algorithm), to execute it completely and produce the result.We know that to execute an algorithm it must be loaded in the main memory. The memory can be used in different forms:Variables (This includes the constant values and temporary values)Program InstructionExecutionAuxiliary SpaceAuxiliary space is extra space or temporary space used by the algorithms during its execution.Memory Usage during program executionInstruction Space is used to save compiled instruction in the memory.Environmental Stack is used to storing the addresses while a module calls another module ...
Read MoreParity Check of a Number
Parity of a number is based on the number of 1’s present in the binary equivalent of that number. When the count of present 1s is odd, it returns odd parity, for an even number of 1s it returns even parity.As we know that the numbers in computer memory are stored in binary numbers, so we can shift numbers easily. In this case, by shifting the bits, we will count a number of 1’s present in the binary equivalent of the given number.Input and OutputInput: A number: 5 Binary equivalent is (101) Output: Parity of 5 is Odd.AlgorithmfinParity(n)Input: The number ...
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