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Articles by Daniol Thomas
Page 10 of 13
Get today's date in (YYYY-MM-DD) format in MySQL?
To get today’s date in (YYYY-MM-DD) format in MySQL, you can use CURDATE().Following is the query to get the current date:mysql> SELECT CURDATE();This will produce the following output:+------------+ | CURDATE() | +------------+ | 2019-04-09 | +------------+ 1 row in set (0.00 sec)You can also use NOW() for this. Following is the query:mysql> SELECT DATE(NOW());This will produce the following output+-------------+ | DATE(NOW()) | +-------------+ | 2019-04-09 | +-------------+ 1 row in set (0.00 sec)
Read MoreMySQL query to get substrings (only the last three characters) from strings?
For this, you can use SUBSTR() method. Let us first create a table:mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(20)); Query OK, 0 rows affected (1.31 sec)Following is the query to insert some records in the table using insert command:mysql> insert into DemoTable(FirstName) values('John'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(FirstName) values('Carol'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable(FirstName) values('Robert'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(FirstName) values('Chris'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable(FirstName) values('David'); ...
Read MoreHow to compare DateTime Column with only Date not time in MySQL?
To compare DateTime column with only Date, you need to use the Date() method. Following is the syntax. Below, you need to date in the 'yourDateValue':select *from yourTableName where Date(yourColumnName)='yourDateValue';Let us first create a table:mysql> create table DemoTable ( ArrivalTime datetime ); Query OK, 0 rows affected (0.74 sec)Following is the query to insert some records in the table using insert command:mysql> insert into DemoTable values('2019-01-31 02:34:56'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('2019-04-09 18:20:58'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('2019-05-11 19:45:23'); Query OK, 1 row affected (0.13 ...
Read MoreMySQL query to delete a record with the lowest ID?
To delete record with the lowest id, you can use the following syntax:delete from yourTableName order by yourColumnName limit 1;Let us first create a table:mysql> create table DemoTable ( Id int, Name varchar(20) ); Query OK, 0 rows affected (0.75 sec)Following is the query to insert records in the table using insert command:mysql> insert into DemoTable values(10, 'Larry'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(100, 'Mike'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(30, 'Sam'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(90, 'Chris'); Query ...
Read MoreAlter row_format to dynamic in MySQL?
To alter row_format to dynamic in MySQL, following is the syntax:ALTER TABLE yourTableName ROW_FORMAT=DYNAMIC;Let us first create a table:mysql> create table DemoTable ( CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, CustomerName varchar(200), CustomerAge int, CustomerAddress varchar(200) ); Query OK, 0 rows affected (0.73 sec)Let us check the description of table using DESC command:mysql> desc DemoTable;This will produce the following output:+-----------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra ...
Read MoreWrite an example JDBC program demonstrating the batch processing with CallableStatement object?
Grouping related SQL statements into a batch and executing/submitting them at once is known as batch processing. The Statement interface provides methods to perform batch processing such as addBatch(), executeBatch(), clearBatch().Follow the steps given below to perform batch updates using the CallableStatement object:Register the driver class using the registerDriver() method of the DriverManager class. Pass the driver class name to it, as a parameter.Connect to the database using the getConnection() method of the DriverManager class. Passing URL (String), username (String), password (String) as parameters to it.Set the auto-commit to false using setAutoCommit() method of the Connection interface.Create a CallableStatement object ...
Read MoreWhat is the syntax for input parameters (variables) in a MySQL query?
To set a variable in MySQL, you need to use the SET command. Following is the syntax:set @yourVariableName:=yourValue; select *from yourTableName where yourColumnName=@yourVariableName;Let us first create a table:mysql> create table DemoTable ( Id int, FirstName varchar(20), LastName varchar(20) ); Query OK, 0 rows affected (0.83 sec)Following is the query to insert some records in the table using insert command:mysql> insert into DemoTable values(10, 'Carol', 'Taylor'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(20, 'John', 'Doe'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(30, 'John', 'Smith'); Query OK, 1 row ...
Read MoreHow do I find out whether the underlying database supports batch processing?
Not all the databases support batch processing therefore before proceeding with batch updates in your application. You need to verify whether the database you are trying to communicate supports batch processing/batch updates or not.You can do so using the supportsBatchUpdates() method of the DatabaseMetaData interface.Follow the steps given below:Register the driver class using the registerDriver() method of the DriverManager class. Pass the driver class name to it, as a parameter.Connect to the database using the getConnection() method of the DriverManager class. Passing URL (String), username (String), password (String) as parameters to it.Create a DatabaseMetaData object using the getMetaData() method of ...
Read MoreHow to process SQL statements with JDBC explain with an example?
To process an SQL statement, you need to follow the steps given below:Establish the connection.Create a statement.Execute the statement/query.Process the result.Close the connection.Establishing a ConnectionTo process SQL statements first of all you need to establish connection with the desired DBMS or, file System or, other data sources.To do so, Register the JDBC driver class, corresponding to the DataSource you need to the DriverManager using the registerDriver() method.Driver myDriver = new com.mysql.jdbc.Driver(); DriverManager.registerDriver(myDriver);This method accepts an object of the Driver class; it registers the specified Driver with the DriverManager.You can also register the driver using the forName() method. This method loads ...
Read MoreWhat is RowId object in JDBC Explain?
A RowId is a built-in type of SQL which is an address of a row in a table of a database. The RowId interface of the java.sql package maps with the SQL ROWID value.RowId values are unique for every row and they are the fastest way to access a row. You cannot use this as a primary key of a table.Retrieving RowId objectsYou can retrieve the RowId of a particular row using the getRowId() method of the ResultSet, CallableStatement, PreparedStatement interfaces.This method accepts a String value representing a column label or, an integer value representing the column index and returns ...
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