Added AggregateQueries#baseUserCount

Counts how many users Plan knows about

Plan/common/src/main/java/com/djrapitops/plan/db/sql/queries/AggregateQueries.java

@@ -0,0 +1,51 @@
+/*
+ *  This file is part of Player Analytics (Plan).
+ *
+ *  Plan is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License v3 as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Plan is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with Plan. If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.djrapitops.plan.db.sql.queries;
+
+import com.djrapitops.plan.db.access.Query;
+import com.djrapitops.plan.db.access.QueryAllStatement;
+import com.djrapitops.plan.db.sql.tables.UsersTable;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+/**
+ * Static method class for queries that count how many entries of particular kinds there are.
+ *
+ * @author Rsl1122
+ */
+public class AggregateQueries {
+
+    private AggregateQueries() {
+        /* Static method class */
+    }
+
+    /**
+     * Count how many users are in the Plan database.
+     *
+     * @return Count of base users, all users in a network.
+     */
+    public static Query<Integer> baseUserCount() {
+        String sql = "SELECT COUNT(1) as c FROM " + UsersTable.TABLE_NAME;
+        return new QueryAllStatement<Integer>(sql) {
+            @Override
+            public Integer processResults(ResultSet set) throws SQLException {
+                return set.next() ? set.getInt("c") : 0;
+            }
+        };
+    }
+}