diff --git a/src/main/java/org/gcube/accounting/utility/postgresql/PostgreSQLQuery.java b/src/main/java/org/gcube/accounting/utility/postgresql/PostgreSQLQuery.java
index 8833737..45534e2 100644
--- a/src/main/java/org/gcube/accounting/utility/postgresql/PostgreSQLQuery.java
+++ b/src/main/java/org/gcube/accounting/utility/postgresql/PostgreSQLQuery.java
@@ -1,6 +1,7 @@
 package org.gcube.accounting.utility.postgresql;
 
 import java.io.Serializable;
+import java.sql.SQLException;
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.SortedSet;
@@ -8,9 +9,14 @@ import java.util.TimeZone;
 import java.util.TreeSet;
 
 import org.gcube.documentstore.records.Record;
+import org.postgresql.core.Utils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class PostgreSQLQuery {
 
+	protected static final Logger logger = LoggerFactory.getLogger(PostgreSQLQuery.class);
+	
 	private static final String UTC_TIME_ZONE = "UTC";
 	
 	public static final TimeZone DEFAULT_TIME_ZONE = TimeZone.getTimeZone(UTC_TIME_ZONE);
@@ -19,12 +25,12 @@ public class PostgreSQLQuery {
 	
 	protected StringBuffer stringBuffer;
 	
-	protected String getQuotedString(String string) {
-		StringBuffer buffer = new StringBuffer();
-		buffer.append("'");
-		buffer.append(string);
-		buffer.append("'");
-		return buffer.toString();
+	protected String getQuotedString(String string) throws SQLException {
+		StringBuilder builder = new StringBuilder();
+		builder.append("'");
+		Utils.escapeLiteral(builder, string, false);
+		builder.append("'");
+		return builder.toString();
 	}
 	
 	protected void appendString(String string) {
@@ -33,11 +39,11 @@ public class PostgreSQLQuery {
 		stringBuffer.append("'");
 	}
 	
-	protected void appendValue(Serializable serializable) {
+	protected void appendValue(Serializable serializable) throws SQLException {
 		stringBuffer.append(getValue(serializable));
 	}
 	
-	protected String getValue(Serializable serializable) {
+	protected String getValue(Serializable serializable) throws SQLException {
 		if(serializable instanceof Number) {
 			return serializable.toString();
 		}
@@ -94,8 +100,14 @@ public class PostgreSQLQuery {
 		}
 		stringBuffer.append(") VALUES");
 		stringBuffer.append(values);
-		stringBuffer.append(");");
-		return stringBuffer.toString();
+		stringBuffer.append(")");
+		stringBuffer.append(" ON CONFLICT (");
+		String dbField = recordToDBFields.getTableField(Record.ID);
+		stringBuffer.append(dbField);
+		stringBuffer.append(") DO NOTHING;");
+		String ret = stringBuffer.toString();
+		logger.trace("Created query {}", ret);
+		return ret;
 	}
 	
 }