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Database Articles
Page 262 of 547
What would be the effect on summary output when I use explicit sort order (ASC or DESC) with column names in the GROUP BY list along with "WITH ROLLUP" modifier?
In the case, where we use explicit sort order (ASC or DESC) with column names in the GROUP BY list along with the “WITH ROLLUP” modifier, the summary rows added by ROLLUP still appear after the rows from which they calculated regardless of the sort order.As we know that the default sort order is ascending hence in the example below if we will not use any explicit sort order then the output would be as follows −mysql> Select sr, SUM(Price) AS Price from ratelist Group by sr with rollup; +-----+-------+ | sr | Price | +-----+-------+ | 1 | ...
Read MoreWhich statement, other than START TRANSACTION, is used for starting a transaction?
We can also use the BEGIN statement to start a new transaction. It is the same as the START TRANSACTION statement.Examplemysql> BEGIN; Query OK, 0 rows affected (0.00 sec) mysql> INSERT INTO Marks Values(1, 'Aarav', 'History', 40); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Marks Values(2, 'Harshit', 'History', 48); Query OK, 1 row affected (0.00 sec) mysql> ROLLBACK; Query OK, 0 rows affected (0.04 sec)In this example, the transaction is initiated by the BEGIN Statement rather than START TRANSACTION statement. Two INSERT statements are then executed followed by a ROLLBACK statement. ROLLBACK statement will ...
Read MoreHow can MySQL produce the output in a vertical format rather than tabular format?
By using \G at the end of MySQL statement, it returns the output in a vertical format rather than a tabular format. Consider the example below −mysql> Select curdate(); +------------+ | curdate() | +------------+ | 2017-11-06 | +------------+ 1 row in set (0.00 sec) mysql> Select CURDATE()\G *************************** 1. row *************************** CURDATE(): 2017-11-06 1 row in set (0.00 sec)From the example above, the difference of using \G at the end of the MySQL statement can be understood. It returns the same output in a vertical format rather than a tabular format.
Read MoreHow does MySQL determine the end of the statement?
MySQL determines the end of a statement when it encounters any one of the followings −Semicolon(;)Generally, MySQL determines the end of the statement, single-line or multiple-line, when it encounters the termination semicolon(;). Consider the examples below, mysql> Select * from employee; (Single line statement) mysql> Select * -> from -> employee; (Multiple line statement)In both cases, MySQL returns the result set after encountering the semicolon, which means the end of the statement.\G option\G option means to send the current state to the server to be executed and display the result in a vertical format. When we ...
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 ...
Read MoreHow can I display MySQL query result vertically?
With the use of ego, \G option at end of a statement, we can get the result set in vertical format. Consider the following example −mysql> Select * from Student where name = 'Aarav'\G *************************** 1. row *************************** Name: Aarav RollNo: 150 Grade: M.SC 1 row in set (0.00 sec)
Read MoreIn MySQL, how it can be possible to specify a sort order using a column that is not retrieved by the query?
Actually, as we know that we can specify a sort order with the help of the ORDER BY clause. We need to write the ORDER BY keyword followed by the name of the column on which we want to sort the table. It is not necessary that we have to use that column name after the SELECT keyword in the query.Examplemysql> Select Sr, Item from ratelist ORDER BY Price; +----+------+ | Sr | Item | +----+------+ | 5 | T | | 1 | A | | 2 | B | | 4 | h | ...
Read MoreHow the MySQL command that you are in the process of entering can be canceled?
Suppose if we do not want to execute a command that we are entering, then we can use a clear \c option which clears the current input. For example, the use of \c option can be done as follows −mysql> Select * -> from\cIn the example above, when we use \c in a statement, MySQL clears the current input and returns back to the MySQL prompt for accepting other statements.
Read MoreHow can we convert subqueries to INNER JOIN?
To make it understand we are using the data from the following tables −mysql> Select * from customers; +-------------+----------+ | Customer_Id | Name | +-------------+----------+ | 1 | Rahul | | 2 | Yashpal | | 3 | Gaurav | | 4 | Virender | +-------------+----------+ 4 rows in set (0.00 sec) mysql> Select * from reserve; +------+------------+ | ID | Day | +------+------------+ | 1 | 2017-12-30 | | ...
Read MoreWhat are the different MySQL prompts we have on the command line?
As we know that after writing the first line of multiple-line queries, MySQL changes the prompt. The following table shows different MySQL prompts and it's meaning −PromptMeaning mysql>It means MySQL is ready for a new command. →It means that MySQL is waiting for the next line of multiple-line command. ‘>It means that MySQL is waiting for the next line, waiting for the completion of a string that began with a single quote. “>It means that MySQL is waiting for the next line, waiting for the completion of a string that began with a double quote. `>It means that MySQL is waiting ...
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