A CLOB (character large object) value can be up to 2,147,483,647 characters long. A CLOB is used to store unicode character-based data, such as large documents in any character set.
The length is given in number characters for both CLOB, unless one of the suffixes K, M, or G is given, relating to the multiples of 1024, 1024*1024, 1024*1024*1024 respectively.
Length is specified in characters (unicode) for CLOB.{CLOB |CHARACTER LARGE OBJECT}(length [{{K |M |G}]))
Corresponding Compile-Time Java Type
java.sql.Clob
JDBC Metadata Type (java.sql.Types)
CLOB
java.sql.Clob
CLOB
Use the getClob method on the java.sql.ResultSet to retrieve a CLOB handle to the underlying data.
import java.sql.*;
public class clob
{
public static void main(String[] args) {
try {
String url = "jdbc:derby:clobberyclob;create=true";
Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance();
Connection conn = DriverManager.getConnection(url);
Statement s = conn.createStatement();
s.executeUpdate("CREATE TABLE documents (id INT, text CLOB(64 K))");
conn.commit();
// --- add a file
java.io.File file = new java.io.File("asciifile.txt");
int fileLength = (int) file.length();
// - first, create an input stream
java.io.InputStream fin = new java.io.FileInputStream(file);
PreparedStatement ps = conn.prepareStatement("INSERT
INTO documents VALUES (?, ?)");
ps.setInt(1, 1477);
// - set the value of the input parameter to the input stream
ps.setAsciiStream(2, fin, fileLength);
ps.execute();
conn.commit();
// --- reading the columns
ResultSet rs = s.executeQuery("SELECT text FROM documents
WHERE id = 1477");
while (rs.next()) {
java.sql.Clob aclob = rs.getClob(1);
java.io.InputStream ip = rs.getAsciiStream(1);
int c = ip.read();
while (c > 0) {
System.out.print((char)c);
c = ip.read();
}
System.out.print("\n");
// ...
}
} catch (Exception e) {
System.out.println("Error! "+e);
}
}
}