private static String loadUpdate(LoadConfiguration config, String prefix) {
		StringBuilder b = new StringBuilder();
		String name = config.getTable() + "_ext_" + prefix;
		b.append("UPDATE ");
		b.append(config.getTable());
		b.append(" into_table set ");

		for (int i = 0; i < config.getUpdateColumns().size(); i++) {
			b.append(config.getUpdateColumns().get(i) + "=from_table." + config.getUpdateColumns().get(i));
			if (i + 1 < config.getUpdateColumns().size()) {
				b.append(", ");
			}
		}

		b.append(" FROM ");
		b.append(name);
		b.append(" from_table where ");

		for (int i = 0; i < config.getMatchColumns().size(); i++) {
			b.append("into_table." + config.getMatchColumns().get(i) + "=from_table." + config.getMatchColumns().get(i));
			if (i + 1 < config.getMatchColumns().size()) {
				b.append(" and ");
			}
		}

		if (StringUtils.hasText(config.getUpdateCondition())) {
			b.append(" and " + config.getUpdateCondition());
		}

		return b.toString();
	}
Builds sql clause to load data into a database.

@param config
           Load configuration.
@param prefix
           Prefix for temporary resources.
@return
           the load DDL
extensions/spring-xd-extension-gpfdist/src/main/java/org/springframework/xd/greenplum/support/SqlUtils.java