CLOB

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.

Syntax

{CLOB |CHARACTER LARGE OBJECT} [ ( length [{K |M |G}] ) ]

Default

A CLOB without a specified length is defaulted to two gigabytes (2,147,483,647).

Corresponding Compile-Time Java Type

java.sql.Clob

JDBC Metadata Type (java.sql.Types)

CLOB

Use the getClob method on the java.sql.ResultSet to retrieve a CLOB handle to the underlying data.

Related Information

See java.sql.Blob and java.sql.Clob.

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);
        }
    }
}