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Database Articles
Page 139 of 546
How we have multiple stored GENERATED COLUMNS in MySQL table with CREATE TABLE statement?
It is quite possible to add multiple stored generated columns in a MySQL table. It can be illustrated with the following example as follows −Examplemysql> Create table profit1(cost int, price int, profit int AS (price-cost) STORED, price_revised int AS (price-2) STORED); Query OK, 0 rows affected (0.36 sec) mysql> Describe profit1; +---------------+---------+------+-----+---------+------------------+ | Field | Type | Null | Key | Default | Extra | +---------------+---------+------+-----+---------+------------------+ | cost | int(11) | YES | | NULL | ...
Read MoreHow can we alter table to add MySQL stored GENERATED COLUMNS?
For adding MySQL stored GENERATED COLUMNS in a table, we can use the same syntax as adding a column just adding “AS(expression)” after the data type. Its syntax would be as follows −SyntaxALTER TABLE table_name ADD COLUMN column_name AS(expression)STORED;Examplemysql> ALTER TABLE employee_data_stored ADD COLUMN FULLName Varchar(200) AS (CONCAT_WS(" ", 'First_name', 'Last_name')) STORED; Query OK, 2 rows affected (1.23 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> Describe employee_data_stored; +------------+--------------+------+-----+---------+------------------+ | Field | Type | Null | Key | Default | Extra | +------------+--------------+------+-----+---------+------------------+ | ID ...
Read MoreHow can we write PHP script to get the list of MySQL database?
We can write the following PHP script to get the list of available MySQL databases −Example
Read MoreWhat is MySQL GENERATED COLUMN and how to use it while creating a table?
Basically generated columns are a feature that can be used in CREATE TABLE or ALTER TABLE statements and is a way of storing the data without actually sending it through the INSERT or UPDATE clause in SQL. This feature has been added in MySQL 5.7. A generated column works within the table domain. Its syntax would be as follows −Syntaxcolumn_name data_type [GENERATED ALWAYS] AS (expression) [VIRTUAL | STORED] [UNIQUE [KEY]]Here, first of all, specify the column name and its data type.Then add the GENERATED ALWAYS clause to indicate that the column is a generated column.Then, indicate whether the type of ...
Read MoreWhat are the different types of MySQL GENERATED COLUMNS?
We have two types of MYSQL generated columns as follows −VIRTUAL GENERATED COLUMNAs the name suggests, this kind of generated column will not take any disk space. It can be generated with or without using the keyword ‘virtual’. To understand we are illustrating it in the following example −Examplemysql> Create table triangle(SideA DOUBLE, SideB DOUBLE, SideC DOUBLE AS (SQRT(SideA * SideB + SideB * SideB))); Query OK, 0 rows affected (0.44 sec) mysql> Describe Triangle; +-------+--------+------+-----+---------+-------------------+ | Field | Type | Null | Key | Default | Extra | +-------+--------+------+-----+---------+-------------------+ | SideA ...
Read MoreHow can we create MySQL view by selecting data based on pattern matching from base table?
MySQL LIKE operator is used to select data based on pattern matching. Similarly, we can use LIKE operator with views to select particular data based on pattern matching from the base table. To understand this concept we are using the base table ‘student_info’ having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Chandigarh | Literature | | 125 | Raman | Shimla | Computers | | 130 | ...
Read MoreHow to write PHP script by using MySQL JOINS inside it to join two MySQL tables?
We can use the syntax of MySQL JOIN for joining two tables into the PHP function – mysql_query(). This function is used to execute the SQL command and later another PHP function – mysql_fetch_array() can be used to fetch all the selected data.To illustrate it we are having the following example −ExampleIn this example, we are using two MySQL tables which have the following data −mysql> SELECT * FROM tcount_tbl; +-----------------+----------------+ | tutorial_author | tutorial_count | +-----------------+----------------+ | mahran | 20 | | mahnaz | ...
Read MoreHow can we create a MySQL temporary table by using PHP script?
As we know that PHP provides us the function named mysql_query() to create a MySQL table. Similarly, we can use mysql_query() function to create MySQL temporary table. To illustrate this, we are using the following example −ExampleIn this example, we are creating a temporary table named ‘SalesSummary’ with the help of PHP script in the following example − Creating MySQL Temporary Tables
Read MoreWhich PHP function is used to release cursor memory associated with MySQL result?
PHP uses mysql_free_result() function to release the cursor memory associated with MySQL result. It returns no value.SyntaxMysql_free_result(result);Followings are the parameters used in this function −Sr.NoParameter & Description1ResultRequired- Specifies a result set identifier returned by mysql_query(), mysql_store_result() or mysql_use_result()
Read MoreHow can we use logical operators while creating MySQL views?
MySQL views can be created by using logical operators like AND, OR, and NOT. It can be illustrated with the help of following examples −Views with AND operatorAs we know that logical AND operator compares two expressions and returns true if both the expressions are true. In the following example, we are creating a view which has the conditions based on ‘AND’ operator.ExampleThe base table is Student_info having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History ...
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