Inserting, Updating,and Deleting Data - Java Database Programming Bible - page 212

One of the most useful tools provided by JDBC is the capability to retrieve information about the data
returned in a ResultSet . This information is obtained using the JDBC ResultSetMetaData object
reviewed in the next section .

JDBC ResultSetMetaData

In addition, two methods have been added that use the ResultSetMetaData class to get information
about the table being edited. The two MetaData objects that follow are capable of returning the table
information required:

DatabaseMetaData , which returns information at the database level

ResultSetMetaData , which returns information at the ResultSet level

The reason for using the ResultSetMetaData object in this example is to restrict the column
information to just the columns being displayed and to defer discussion of the DatabaseMetaData
object until ResultSets have been discussed, since it makes heavy use of ResultSets to return
information.

JDBC ResultSetMetaData provides access to different kinds of information about the data in a
table, including column names and data types. Some of the most useful ResultSet MetaData
methods are the following:

int getColumnCount()

String getColumnName(int column)

String getColumnTypeName(int column)

The following usage is very straightforward. To get the names of all columns in a table, for example, a
simple query is executed to return a ResultSet used to get the ResultSetMetaData . This is then
queried for the desired information.

String SQLCommand = "SELECT * FROM "+tableName+";";

try {

Connection con = DriverManager.getConnection(url);

Statement stmt = con.createStatement();

ResultSet rs = stmt.executeQuery(SQLCommand);

ResultSetMetaData md = rs.getMetaData();

String[] columnNames = new String[md.getColumnCount()];

for(int i=0;i<columnNames.length;i++){

columnNames[i] = md.getColumnLabel(i+1);

}

con.close();

}