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Articles by Arushi
Page 7 of 9
Java DatabaseMetaData supportsTransactionIsolationLevel() method with example
JDBC provides support 5 transaction isolation levels through Connection interface.TRANSACTION_NONE: It is represented by integer value 0 does not support transactions.TRANSACTION_READ_COMMITTED: It is represented by integer value 2 supports transactions allowing Non-Repeatable Reads and, Phantom Reads.TRANSACTION_READ_UNCOMMITTED: It is represented by integer value 1 supports transactions allowing Dirty Reads, Non-Repeatable Reads and, Phantom Reads.TRANSACTION_REPEATABLE_READ: It is represented by integer value 4 supports transactions allowing only Phantom Reads.TRANSACTION_SERIALIZABLE: It is represented by integer value 8 supports transactions with out allowing Dirty Reads, Non-Repeatable Reads and, Phantom Reads.The supportsTransactionIsolationLevel() method of the DatabaseMetaData interface is used to determine whether the underlying database supports ...
Read MoreWhat are the transaction isolation levels supported by JDBC API?
JDBC provides support 5 transaction isolation levels through Connection interface.TRANSACTION_NONE: It is represented by integer value 0 does not support transactions.TRANSACTION_READ_COMMITTED: It is represented by integer value 2 supports transactions allowing Non-Repeatable Reads and, Phantom Reads.TRANSACTION_READ_UNCOMMITTED: It is represented by integer value 1 supports transactions allowing Dirty Reads, Non-Repeatable Reads and, Phantom Reads.TRANSACTION_REPEATABLE_READ: It is represented by integer value 4 supports transactions allowing only Phantom Reads.TRANSACTION_SERIALIZABLE: It is represented by integer value 8 supports transactions with out allowing Dirty Reads, Non-Repeatable Reads and, Phantom Reads.Following JDBC example displays all the transactions levels provided by the Connection interface of the JDBC ...
Read MoreJava DatabaseMetaData supportsUnion() method with example.
The SQL UNION clause/operator is used to combine the results of two or more SELECT statements without returning any duplicate rows.To use this UNION clause, each SELECT statement must haveThe same number of columns selectedThe same number of column expressionsThe same data type andHave them in the same orderBut they need not have to be in the same length.The basic syntax of a UNION clause is as follows −SyntaxSELECT column1 [, column2 ] FROM table1 [, table2 ] [WHERE condition] UNION SELECT column1 [, column2 ] FROM table1 [, table2 ] [WHERE condition]The supportsUnion() method of the DatabaseMetaData interface is used to ...
Read MoreWhat is ResultSet holdability in JDBC?
ResultSet holdability determines whether the ResultSet objects (cursors) should be closed or held open when a transaction (that contains the said cursor/ ResultSet object) is committed using the commit() method of the Connection interface.You can set the ResultSet holdability using the setHoldability() method of the Connection interface.con.setHoldability(ResultSet.CLOSE_CURSORS_AT_COMMIT);The ResultSet interface provides two values to specify the holdability of a ResultSet namely CLOSE_CURSORS_AT_COMMIT and, HOLD_CURSORS_OVER_COMMIT.Let us create a table with name MyPlayers in MySQL database using CREATE statement as shown below −CREATE TABLE MyPlayers( ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), ...
Read MoreJava ResultSet isBeforeFirst() method with example
When we execute certain SQL queries (SELECT query in general) they return tabular data.The java.sql.ResultSet interface represents such tabular data returned by the SQL statements.i.e. the ResultSet object holds the tabular data returned by the methods that execute the statements which quires the database (executeQuery() method of the Statement interface in general).The ResultSet object has a cursor/pointer which points to the current row. Initially this cursor is positioned before first row.The isBeforeFirst() method of the ResultSet interface is used to determine whether the cursor is at the default position of the ResultSet.rs.isBeforeFirst();This method returns an boolean this value is true, if the cursor is ...
Read MoreHow to retrieve the contents of a ResultSet from last to first in JDBC?
ResultSet objectCertain SQL queries (especially SELECT) returns tabular data, In JDBC the object of the java.sql.ResultSet interface holds the tabular data returned by the methods that execute the statements which quires the database (executeQuery() method of the Statement interface in general).ResultSet Cursor/pointerThe ResultSet object has a cursor/pointer which points to the current row. Initially this cursor is positioned before first row.There are two types of result sets namely, forward only and, bidirectional. By default the ResultSet we get by the executeQuery() method is of the type forward only. Using this you can traverse/move the cursor only forward direction.Bidirectional ResultSetA bi-directional ResultSet ...
Read MoreHow to get all table names from a database using JDBC?
You can get the list of tables in the current database in MySQL using the SHOW TABLES query.Show tables;Following JDBC program retrieves the list of tables in the database by executing the show tables query.Exampleimport java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; public class ListingTables { public static void main(String args[]) throws Exception { //Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver()); //Getting the connection String mysqlUrl = "jdbc:mysql://localhost/mydatabase"; Connection con = DriverManager.getConnection(mysqlUrl, "root", "password"); System.out.println("Connection established......"); //Creating a Statement object ...
Read MoreHow to Maintain an open ResultSet after commit in JDBC?
ResultSet holdability determines whether the ResultSet objects (cursors) should be closed or held open when a transaction (that contains the said cursor/ ResultSet object) is committed using the commit() method of the Connection interface.ResultSet interface provides two values to specify the holdability namely CLOSE_CURSORS_AT_COMMIT and HOLD_CURSORS_OVER_COMMITIf the holdability of the ResultSet object is set to this value. Whenever you commit/save a transaction using the commit() method of the Connection interface, the ResultSet objects created in the current transaction (that are already opened) will be held open.Therefore, if you need to hold the ResultSet cursor open after the commit automatically, set ...
Read MoreHow to get the table name of the current ResultSet using JDBC?
You can get the name of the table in the current ResultSet object using the getTableName() method of the ResultSetMetaData interface. This method accepts an integer value representing the index of a column and, returns a String value representing the name of the table that contains the given column.Let us create a table with name MyPlayers in MySQL database using CREATE statement as shown below −CREATE TABLE MyPlayers( ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), PRIMARY KEY (ID) );Now, we will insert 7 records in MyPlayers table using INSERT statements −insert into ...
Read MoreHow to get Row and Column Count from ResultSet in JDBC
Row countThe last() method of the ResultSet interface moves the cursor to the last row of the ResultSet and, the getRow() method returns the index/position of the current row.Therefore, to get the number of rows move the cursor to the last row using the last() method and get the position of that (last) row using the getRow() method.Let us create a table with name MyPlayers in MySQL database using CREATE statement as shown below −CREATE TABLE MyPlayers( ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), PRIMARY KEY (ID) );Now, we will insert 7 records in ...
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