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Articles by karthikeya Boyini
Page 126 of 143
How do I get the average string length in MySQL?
To get the average string length in MySQL, we will work around a query that gets rows from 1 to 10 and displays the result.Let us first create a table. The query to create a table is as follows −mysql> create table AverageString -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Value varchar(20) -> ); Query OK, 0 rows affected (0.66 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into AverageString(Value) values('MySQL Query'); Query OK, 1 row ...
Read MoreWhat does % stand for in host column and how to change user's password?
The localhost means you can access from same machine while from % the remote host access is possible. The syntax is as follows to change the user password.SET PASSWORD FOR 'yourUserName'@'localhost' ='yourPassword';First check the user and host from MySQL.user table. The query is as follows −mysql> select user, host from MySQL.user;Here is the output −+------------------+-----------+ | user | host | +------------------+-----------+ | Bob | % | | Manish | % ...
Read MoreSet Optimal MySQL configuration in my.cnf?
First, you need to open my.cnf file. The following is the query to get the directory location of the config file on Windows −mysql> select @@datadir;Output+---------------------------------------------+ | @@datadir | +---------------------------------------------+ | C:\ProgramData\MySQL\MySQL Server 8.0\Data\ | +---------------------------------------------+ 1 row in set (0.00 sec)Here is the snapshot of the directory −Now open my.cnf file. The snapshot is as follows −If you want to add more data to cache, ...
Read MoreHow do you get the last access (and/or write) time of a MySQL database?
To get the last access time, try the following syntax −SELECT update_time FROM INFORMATION_SCHEMA.TABLES WHERE table_schema = 'yourDatabaseName' AND table_name = 'yourTableName'The above syntax gives the last access information about MyISAM engine type.Here, our database is ‘business’ and we will be using the table with the name ‘twoprimarykeytabledemo'.To get last access time of MySQL database, use the following query.Case 1 − The query is as follows −mysql> SELECT update_time -> FROM INFORMATION_SCHEMA.TABLES -> WHERE table_schema = 'business' -> AND table_name = 'twoprimarykeytabledemo';The output is as follows −+---------------------+ | UPDATE_TIME ...
Read MoreHow to check whether a stored procedure exist in MySQL?
Let us first create a stored procedure −mysql> DELIMITER // mysql> CREATE PROCEDURE ExtenddatesWithMonthdemo(IN date1 datetime, IN NumberOfMonth int ) -> BEGIN -> SELECT DATE_ADD(date1, INTERVAL NumberOfMonth MONTH) AS ExtendDate; -> END; -> // Query OK, 0 rows affected (0.20 sec) mysql> DELIMITER ;Now you check whether the stored procedure exists with the help SHOW CREATE command.The query is as follows −mysql> SHOW CREATE PROCEDURE ExtenddatesWithMonthdemo; The following is the output displaying the details of the stored procedure we created above: +--------------------------+--------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ | Procedure | sql_mode ...
Read MoreHow to upgrade MySQL server from command line?
First, you need to open the CMD with the help of shortcut key Windows+R key.After typing cmd, press the OK button. On pressing, you will get a command prompt. The screenshot is as follows −After that, you need to reach the /bin directory. Follow the below instructions. If you are a Windows user, then use the below query to reach the /bin directory.The query is as follows −mysql> select @@datadir;The following is the output displaying the path −+---------------------------------------------+ | @@datadir ...
Read MoreC++ Program to Implement Rolling Hash
Rolling hash is a hash function in which the input is hashed in a window that moves through the input.Rabin-Karp is popular application of rolling hash. The rolling hash function proposed by Rabin and Karp calculates an integer value. For a string the integer value is numeric value of a string.The Rabin–Karp string search algorithm is often explained using a very simple rolling hash function that only uses multiplications and additions −H=c1ak-1+c2ak-2+….+ cka0.Where, a is a constant, and c1, c2….ck are the input characters. In order to manipulate Huge value of H, mod n is done.AlgorithmBegin Declare a constant ...
Read MoreHow to flush output stream after writing bytes
Let us first crate OutputStream with file input.txt −FileOutputStream fileStream = new FileOutputStream("E:/input.txt"); DataOutputStream dataStream = new DataOutputStream(fileStream);Now, the writeBytes() method writes out the string to the underlying output stream as a sequence of bytes.dataStream.writeBytes("Demo text!");Flush the output stream −dataStream.flush();The following is an example. Here, our file is “E:/input.txt” and at the end we are flushing the output stream −Exampleimport java.io.DataOutputStream; import java.io.FileOutputStream; public class Demo { public static void main(String[] args) throws Exception { FileOutputStream fileStream = new FileOutputStream("E:/input.txt"); DataOutputStream dataStream = new DataOutputStream(fileStream); dataStream.writeBytes("Demo text!"); ...
Read MoreHow to display message from a stored procedure?
To display message from stored procedure on the basis of conditions, let us use IF-ELSE condition −mysql> DELIMITER // mysql> CREATE PROCEDURE showMessage(value int, Name varchar(20)) BEGIN IF(value > 100) then SELECT CONCAT("HELLO", " ", Name); ELSE SELECT CONCAT("BYE", " ", Name); END IF; END // Query OK, 0 rows affected (0.18 sec) mysql> DELIMITER ;Case 1 − Call the stored procedure using CALL command, when value is more than 100 −call showMessage(200, 'John');This will produce ...
Read MoreMySQL query to select too many rows?
You can use LIMIT for this, which is used to fetch limited number of records. Let us first create a table −mysql> create table DemoTable ( Id int, Name varchar(20) ); Query OK, 0 rows affected (0.53 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(10, 'John'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(11, 'Chris'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(12, 'David'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(13, 'Carol'); Query OK, 1 row affected (0.13 sec) mysql> ...
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