--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/nabble/model/TagImpl.java	Thu Mar 21 19:15:52 2019 -0600
@@ -0,0 +1,138 @@
+package nabble.model;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.sql.Types;
+import java.util.ArrayList;
+import java.util.List;
+import fschmidt.db.postgres.DbDatabaseImpl;
+
+
+final class TagImpl {
+
+	private TagImpl() {}  // never
+
+	static void addTag(Site site,Node node,User user,String label) {
+		try {
+			Connection con = site.getDb().getConnection();
+			PreparedStatement stmt = con.prepareStatement(
+				"insert into tag (node_id,user_id,label) values (?,?,?)"
+			);
+			if( node == null ) {
+				stmt.setNull( 1, Types.INTEGER );
+			} else {
+				stmt.setLong( 1, node.getId() );
+			}
+			if( user == null ) {
+				stmt.setNull( 2, Types.INTEGER );
+			} else {
+				stmt.setLong( 2, user.getId() );
+			}
+			stmt.setString( 3, label );
+			DbDatabaseImpl.executeUpdateIgnoringDuplicateKeys(stmt);
+			stmt.close();
+			con.close();
+		} catch(SQLException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	static int countTags(SiteKey siteKey,String sqlCondition) {
+		try {
+			Connection con = siteKey.getDb().getConnection();
+			try {
+				Statement stmt = con.createStatement();
+				ResultSet rs = stmt.executeQuery(
+					"select count(*) as n from tag where " + sqlCondition
+				);
+				rs.next();
+				int n = rs.getInt("n");
+				rs.close();
+				stmt.close();
+				return n;
+			} finally {
+				con.close();
+			}
+		} catch(SQLException e) {
+			throw new RuntimeException("sqlCondition = "+sqlCondition,e);
+		}
+	}
+
+	static List<String> findTagLabels(Site site,String sqlCondition) {
+		try {
+			List<String> list = new ArrayList<String>();
+			Connection con = site.getDb().getConnection();
+			Statement stmt = con.createStatement();
+			ResultSet rs = stmt.executeQuery(
+				"select distinct label from tag where " + sqlCondition
+			);
+			while( rs.next() ) {
+				list.add( rs.getString("label") );
+			}
+			rs.close();
+			stmt.close();
+			con.close();
+			return list;
+		} catch(SQLException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	static List<Long> findTagUserIds(Site site,String sqlCondition) {
+		try {
+			List<Long> list = new ArrayList<Long>();
+			Connection con = site.getDb().getConnection();
+			Statement stmt = con.createStatement();
+			ResultSet rs = stmt.executeQuery(
+				"select distinct user_id from tag where " + sqlCondition
+			);
+			while( rs.next() ) {
+				list.add( rs.getLong("user_id") );
+			}
+			rs.close();
+			stmt.close();
+			con.close();
+			return list;
+		} catch(SQLException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	static List<Long> findTagNodeIds(Site site,String sqlCondition) {
+		try {
+			List<Long> list = new ArrayList<Long>();
+			Connection con = site.getDb().getConnection();
+			Statement stmt = con.createStatement();
+			ResultSet rs = stmt.executeQuery(
+				"select distinct node_id from tag where " + sqlCondition
+			);
+			while( rs.next() ) {
+				list.add( rs.getLong("node_id") );
+			}
+			rs.close();
+			stmt.close();
+			con.close();
+			return list;
+		} catch(SQLException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	static void deleteTags(SiteKey siteKey,String sqlCondition) {
+		try {
+			Connection con = siteKey.getDb().getConnection();
+			Statement stmt = con.createStatement();
+			stmt.executeUpdate(
+				"delete from tag where " + sqlCondition
+			);
+			stmt.close();
+			con.close();
+		} catch(SQLException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+}