Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Database Articles
Page 469 of 547
How to write a MySQL "LIMIT" in SQL Server?
You need to use TOP(1) in SQL Server. The syntax is as follows −SELECT TOP(1) *FROM yourTableName WHERE yourCondition;To understand the above syntax, let us create a table. The query to create a table is as follows −create table TopDemoInSQLServer ( Id int, Name varchar(10) );The snapshot of creation of table is as follows −Insert some records in the table using insert command. The query is as follows −insert into TopDemoInSQLServer values(10, 'John'); insert into TopDemoInSQLServer values(14, 'Carol'); insert into TopDemoInSQLServer values(1, 'Sam'); insert into TopDemoInSQLServer values(11, 'Bob'); insert into TopDemoInSQLServer values(18, 'David'); insert into TopDemoInSQLServer values(20, 'Sam');The ...
Read MoreHow to work with one database connection object in the entire Java-MySQL application?
Use the singleton design pattern. Here is the Java code that returns a single object −ConnectDatabase.javaimport java.sql.Connection; import java.sql.DriverManager; public class ConnectDatabase { static Connection conn = null; public static Connection getConnection() { if (conn != null) return conn; String database = "test"; String Username = "root"; String password = "123456"; return getConnection(database, Username, password); } private static Connection getConnection(String databaseName, String UserName, String password) { try { Class.forName("com.mysql.jdbc.Driver"); conn ...
Read MoreHow can I set a MySQL database to use MyISAM by default?
To set the default storage engine, use the following syntax −set @@default_storage_engine = ’yourEngineType’;Now implement the above syntax to set the default engine to MyISAM. The query is as follows −mysql> set @@default_storage_engine = 'MyISAM'; Query OK, 0 rows affected (0.05 sec)Now you can check the default engine type with the help of SELECT statement. The query is as follows −mysql> select @@default_storage_engine;The following is the output displaying the engine as MyISAM −+--------------------------+ | @@default_storage_engine | +--------------------------+ | MyISAM | +--------------------------+ 1 ...
Read MoreDoes MySQL support table inheritance?
MySQL uses foreign key constraint instead of inheritance. MySQL does not support table inheritance.You can achieve the same with the help of foreign key constraint. Let us create a table and use the foreign key constraint. The query to create the first table is as follows −mysql> create table Parent_Table -> ( -> ParentId int, -> PRIMARY KEY(ParentId) -> ); Query OK, 0 rows affected (3.59 sec)Now create the second table. The query to create the second table is as follows −mysql> create table Child_Table ...
Read MoreHow 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 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 to achieve case sensitive uniqueness and case insensitive search in MySQL?
You can achieve case sensitive uniqueness and case insensitive search with the help of the following two ways −VARBINARY data type_bin collationVARBINARY data typeTo work with the VARBINARY data type, let us first create a table. The query to create a table is as follows −mysql> create table SearchingDemo2 -> ( -> UserId VARBINARY(128) NOT NULL, -> UNIQUE KEY index_on_UserId2(UserId ) -> )ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; Query OK, 0 rows affected, 1 warning (0.99 sec)Keep in mind UserId has data type VARBINARY(128) and Index(‘index_on_UserId2’) on a column ‘UserId’._bin ...
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 know the exact number of table and columns in a MySQL database?
To get the exact number if table and columns in a MySQL database, use the DISTINCT inside COUNT().Let’s say we have a database ‘sample’ and we need to work on it to get the exact number of table and columns.To achieve it, the query is as follows −mysql> SELECT COUNT(DISTINCT TABLE_NAME) AS TotalTable, Count(Column_Name) AS TOTALColumn -> FROM INFORMATION_SCHEMA.COLUMNS -> WHERE TABLE_SCHEMA = 'sample';The following is the output displaying the count of table and columns in the database ‘sample’ −+------------+-------------+ | TotalTable | TOTALColumn | +------------+-------------+ | ...
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 More