Java Database Connectivity
part 8/17 · 28.8 KB total
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try (Statement stmt = conn.createStatement()) {
stmt.executeUpdate("INSERT INTO MyTable(name) VALUES ('my name')");
}
Note that Connections, Statements, and ResultSets often tie up operating system resources such as sockets or file descriptors. In the case of Connections to remote database servers, further resources are tied up on the server, e.g. cursors for currently open ResultSets. It is vital to close() any JDBC object as soon as it has played its part; garbage collection should not be relied upon. The above try-with-resources construct is a code pattern that obviates this.
Data is retrieved from the database using a database query mechanism. The example below shows creating a statement and executing a query.
try (Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM MyTable")
) {
while (rs.next()) {
int numColumns = rs.getMetaData().getColumnCount();
for (int i = 1; i <= numColumns; i++) {
// Column numbers start at 1.
// Also, there are many methods on the result set to return
// the column as a particular type. Refer to the Sun documentation
// for the list of valid conversions.
System.out.println( "COLUMN " + i + " = " + rs.getObject(i));
}
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