/** Returns a table's primary key columns as a Set of strings. */
public static Set<String> getPrimaryKey(DatabaseMetaData metadata, String tableName)
throws Exception {
Set<String> columns = new HashSet<String>();
ResultSet keys =
metadata.getPrimaryKeys(
metadata.getConnection().getCatalog(), metadata.getUserName(), tableName);
while (keys.next()) {
columns.add(keys.getString(PRIMARY_PK_COL_NAME));
}
keys.close();
return columns;
}
/** Returns a table's columns */
public static List<Column> getColumns(DatabaseMetaData metadata, String tableName)
throws Exception {
List<Column> columns = new ArrayList<Column>();
PreparedStatement stmt =
metadata.getConnection().prepareStatement("SELECT * FROM " + tableName);
ResultSetMetaData rsmeta = stmt.getMetaData();
for (int i = 1, ii = rsmeta.getColumnCount(); i <= ii; ++i) {
columns.add(new Column(rsmeta, i));
}
stmt.close();
return columns;
}
/**
* Returns a table's foreign keys and their columns as a Map from the key name to the ForeignKey
* object.
*
* <p>A foreign key may not have a name. On such a database, 2 foreign keys must reference 2
* different tables. Otherwise there's no way to tell them apart and the foreign key information
* reported by DatabaseMetaData becomes ill-formed.
*/
public static Map<String, ForeignKey> getForeignKeys(DatabaseMetaData metadata, String tableName)
throws Exception {
ResultSet keys =
metadata.getImportedKeys(
metadata.getConnection().getCatalog(), metadata.getUserName(), tableName);
Map<String, ForeignKey> map = new HashMap<String, ForeignKey>();
while (keys.next()) {
String table = keys.getString(IMPORTED_PK_TAB_NAME);
String name = keys.getString(IMPORTED_FK_KEY_NAME);
if (name == null || name.length() == 0) name = "UNNAMED_FK_" + table;
ForeignKey key = map.get(name);
if (key == null) {
map.put(name, key = new ForeignKey(table));
}
key.add(keys.getString(IMPORTED_FK_COL_NAME));
}
keys.close();
return map;
}
