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Database Articles
Page 5 of 546
How can I insert default value in MySQL ENUM data type?
When designing a database, setting default values for certain fields will improve data integrity. In MySQL, ENUM data type allows you to specify predefined values for a column such as status (complete or incomplete). This article helps you to set a default value for ENUM columns, to ensure that even if the data is missing, a suitable value is automatically assigned. Inserting a default value with ENUM data type We can do this with the help of the DEFAULT attribute of the ENUM data type. The DEFAULT attribute causes an ENUM data type to have a default value when a ...
Read MoreDifference between stored procedure and triggers in SQL
Stored Procedures Stored Procedures is a group of pre-compiled SQL statements that is stored in a database and can be reused anytime. It allows you to do many things in one command. So doing several activities in a database will be easier and quicker than before. A stored procedure can be called from SQL commands as well as applications like Python, Java, or PHP. Syntax Following is the syntax to create a stored procedure − CREATE PROCEDURE procedure_name AS BEGIN -- SQL statements END; Example Let us create a stored procedure where it ...
Read MoreCount items in a MySQL table with type ENUM involved?
Counting ENUM items in MySQL In MySQL, ENUM is a data type where it stores the predefined and fixed values making them ideal for categories such as sizes, grades, and statuses. Knowing the frequency of each value inside ENUM columns will allow you to make data-driven decisions. Below, we'll learn how to use MySQL's GROUP BY and COUNT() functions to get the count of ENUM values. GROUP BY(): It is used for aggregating data, as it follows you to perform calculations, such as totals, and averages. ...
Read MoreHow can we create multiple MySQL triggers for the same trigger event and action time?
In MySQL, a trigger is a group of SQL statements performed or fired when a specified event is taken place on tables. The events can include INSERT, UPDATE, and DELETE. Such triggers are used for automating repetitive work, ensuring integrity in data, and keeping audit records without human involvement. The FOLLOWS keyword in MySQL allows the creation of several triggers for the same event and also allows you to select the order of execution. Creating Multiple Triggers for the Same Event When working with triggers, sometimes you might need to define several triggers for the same ...
Read MoreAdd a new value to a column of data type enum in MySQL?
In MySQL, the ENUM is a data type that is used to create a column with a fixed set of values. It is helpful for the fields that have limited alternatives, such as categories, statuses, and color codes. However, as your application evolves, you might need to add more values to the list such as new colors. MySQL allows us to modify ENUM values without dropping and recreating the column. Adding New Value to an ENUM column For adding new values in an ENUM column in MySQL, you shall use the ALTER TABLE command with the MODIFY Keyword. For ...
Read MoreProgram for Fibonacci numbers in PL/SQL
Given ‘n’ numbers the task is to generate the Fibonacci numbers in PL/SQL starting from 0 to n, where the Fibonacci series of integers is in the form 0, 1, 1, 2, 3, 5, 8, 13, 21, 34 Where integers 0 (1st place) and 1 (2nd place) will have a fixed place after that, the previous two digits will be added to get the integer of the next place as shown below. 0+1=1 (3rd place) 1+1=2 (4th place) 2+1=3 (5th place) and So on. Formula Sequence F(n) ...
Read MoreShow MySQL host via SQL Command?
To display MySQL host via SQL command, use the system variable hostname. Query 1 The following is the query to display the host − mysql > select @@hostname; Output Here is the output − +-----------------+ | @@hostname | +-----------------+ | DESKTOP-QN2RB3H | +-----------------+ 1 row in set (0.00 sec) Query 2 Or you can use "show variables" command to show MySQL host via SQL command. show variables where Variable_name like '%host%'; Output The following is the output − +-------------------------------+-----------------+ | Variable_name | Value | +-------------------------------+-----------------+ | host_cache_size | 279 | | hostname | DESKTOP-QN2RB3H | | performance_schema_hosts_size | -1 | | report_host | | +-------------------------------+-----------------+ 4 rows in set (0.07 sec)
Read MoreDifference between hierarchical and network database model in SQL
Hierarchical Data Model In the Hierarchical data model, the relationship between the table and data is defined in parent-child structure. In this structure, data is arranged in the form of a tree structure. This model supports one-to-one and one-to-many relationships. Network Model The Network model arranges data in a graph structure. In this model, each parent can have multiple children, and children can also have multiple parents. This model supports many-to-many relationships as well. Comparison Table ...
Read MoreReverse a Number in PL/SQL
PL/SQL is a block-structured language that combines SQL's functionality with procedural commands. In this article, we will discuss a program in PL/SQL to reverse a given number for example −Input : 98765 Output : 56789 Explanation : reverse number of 98765 is 56789. Input : 56784 Output : 48765 Explanation Reverse number of ‘56784’ is ‘48765’.Approach to find The SolutionTake out the last digit from the number by finding the remainder of num/10.Now add the last digit to another variable reversed_num.Now check if num becomes 0 −If YES, then go to STEP1.If NO, then go to STEP4.Finally, print the ...
Read MoreDifference between correlated and non-collreated subqueries in SQL
SQL query is used to fetch data from the database. In some of the scenario you may need some perquisite data to call subsequent SQL query to fetch data from a table so instead of writing two seperate query we can write SQL query within the query. Therefore subQuery is a way to combine or join them in single query. Subqurey can have two types −Correlated subquery - In correlated subquery, inner query is dependent on the outer query. Outer query needs to be executed before inner queryNon-Correlated subquery - In non-correlated query inner query does not dependent on the outer ...
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