Yet more lastInsertedId revamping. Third time's the charm.

src/main/java/com/samskivert/jdbc/BaseLiaison.java

@@ -38,12 +38,11 @@ public abstract class BaseLiaison implements DatabaseLiaison
 
     @Deprecated
     public int lastInsertedId (Connection conn, String table, String column) throws SQLException {
-        Integer id = lastInsertedId(conn, null, table, column);
-        return (id == null) ? -1 : id;
+        return lastInsertedId(conn, null, table, column);
     }
 
     // from DatabaseLiaison
-    public Integer lastInsertedId (Connection conn, Statement istmt, String table, String column)
+    public int lastInsertedId (Connection conn, Statement istmt, String table, String column)
         throws SQLException
     {
         // if this JDBC driver supports getGeneratedKeys, use it!
@@ -53,7 +52,18 @@ public abstract class BaseLiaison implements DatabaseLiaison
                 return rs.getInt(column);
             }
         }
-        return null;
+        return fetchLastInsertedId(conn, table, column);
+    }
+
+    /**
+     * Requests the last inserted id for the specified table and column. This is used if a JDBC
+     * driver does not support {@code getGeneratedKeys} or an attempt to use that failed.
+     */
+    protected int fetchLastInsertedId (Connection conn, String table, String column)
+        throws SQLException
+    {
+        throw new SQLException(
+            "Unable to obtain last inserted id [table=" + table + ", column=" + column + "]");
     }
 
     // from DatabaseLiaison

src/main/java/com/samskivert/jdbc/DatabaseLiaison.java

@@ -55,9 +55,10 @@ public interface DatabaseLiaison
      *
      * @param istmt the insert statement that generated the keys. May be null if the ORM doesn't
      * have the statement handy.
-     * @return the requested inserted id, or null if no last inserted id can be obtained.
+     * @return the requested inserted id.
+     * @throws SQLException if we are unable to obtain the last inserted id.
      */
-    public Integer lastInsertedId (Connection conn, Statement istmt, String table, String column)
+    public int lastInsertedId (Connection conn, Statement istmt, String table, String column)
         throws SQLException;
 
     /**

src/main/java/com/samskivert/jdbc/HsqldbLiaison.java

@@ -72,13 +72,10 @@ public class HsqldbLiaison extends BaseLiaison
         // HSQL's IDENTITY() does not create any database entities that we need to delete
     }
 
-    @Override // from DatabaseLiaison
-    public Integer lastInsertedId (Connection conn, Statement istmt, String table, String column)
+    @Override
+    protected int fetchLastInsertedId (Connection conn, String table, String column)
         throws SQLException
     {
-        Integer id = super.lastInsertedId(conn, istmt, table, column);
-        if (id != null) return id;
-
         // HSQL does not keep track of per-table-and-column insertion data, so we are pretty much
         // going on blind faith here that we're fetching the right ID. In the overwhelming number
         // of cases that will be so, but it's still not pretty.
@@ -86,7 +83,7 @@ public class HsqldbLiaison extends BaseLiaison
          try {
              stmt = conn.createStatement();
              ResultSet rs = stmt.executeQuery("call IDENTITY()");
-             return rs.next() ? rs.getInt(1) : null;
+             return rs.next() ? rs.getInt(1) : super.fetchLastInsertedId(conn, table, column);
          } finally {
              JDBCUtil.close(stmt);
          }

src/main/java/com/samskivert/jdbc/MySQLLiaison.java

@@ -49,16 +49,19 @@ public class MySQLLiaison extends BaseLiaison
         // AUTO_INCREMENT does not create any database entities that we need to delete
     }
 
-    @Override // from DatabaseLiaison
-    public Integer lastInsertedId (Connection conn, Statement istmt, String table, String column)
+    @Override // from BaseLiaison
+    public int lastInsertedId (Connection conn, Statement istmt, String table, String column)
         throws SQLException
     {
-        // MySQL hackily reports the last inserted key as GENERATED_KEY, so we call super with that
-        // "column name"; but if that doesn't work (we're using an old JDBC driver without support
-        // for returning generated keys), fall back to the old old method
-        Integer id = super.lastInsertedId(conn, istmt, table, "GENERATED_KEY");
-        if (id != null) return id;
+        // MySQL uses "GENERATED_KEY" as the column name for the last inserted key, so we have to
+        // hackily pass that to our super method to get things to work
+        return super.lastInsertedId(conn, istmt, table, "GENERATED_KEY");
+    }
 
+    @Override
+    protected int fetchLastInsertedId (Connection conn, String table, String column)
+        throws SQLException
+    {
         // MySQL does not keep track of per-table-and-column insertion data, so we are pretty much
         // going on blind faith here that we're fetching the right ID. In the overwhelming number
         // of cases that will be so, but it's still not pretty.
@@ -66,7 +69,7 @@ public class MySQLLiaison extends BaseLiaison
         try {
             stmt = conn.createStatement();
             ResultSet rs = stmt.executeQuery("select LAST_INSERT_ID()");
-            return rs.next() ? rs.getInt(1) : null;
+            return rs.next() ? rs.getInt(1) : super.fetchLastInsertedId(conn, table, column);
         } finally {
             JDBCUtil.close(stmt);
         }

src/main/java/com/samskivert/jdbc/PostgreSQLLiaison.java

@@ -34,14 +34,10 @@ public class PostgreSQLLiaison extends BaseLiaison
                 msg.indexOf("An I/O error occured while sending to the backend") != -1);
     }
 
-    // from DatabaseLiaison
-    public Integer lastInsertedId (Connection conn, Statement istmt, String table, String column)
+    @Override
+    protected int fetchLastInsertedId (Connection conn, String table, String column)
         throws SQLException
     {
-        // try the default first, which uses JDBC's getGeneratedKeys mechanism
-        Integer id = super.lastInsertedId(conn, istmt, table, column);
-        if (id != null) return id;
-
         // PostgreSQL's support for auto-generated ID's comes in the form of appropriately named
         // sequences and DEFAULT nextval(sequence) modifiers in the ID columns. To get the next ID,
         // we use the currval() method which is set in a database sessions when any given sequence
@@ -50,7 +46,7 @@ public class PostgreSQLLiaison extends BaseLiaison
         try {
             ResultSet rs = stmt.executeQuery(
                 "select currval('\"" + table + "_" + column + "_seq\"')");
-            return rs.next() ? rs.getInt(1) : null;
+            return rs.next() ? rs.getInt(1) : super.fetchLastInsertedId(conn, table, column);
         } finally {
             JDBCUtil.close(stmt);
         }