diff --git a/sqlExport.py b/sqlExport.py
index 9f294fb..82c74ff 100644
--- a/sqlExport.py
+++ b/sqlExport.py
@@ -72,7 +72,9 @@ try:
 
     c.execute("CREATE TABLE IF NOT EXISTS transactions (" +
               createDefinitionsFromTableMap(tableMapping['transactions']) +
-              ", CONSTRAINT `fk_member_uid` FOREIGN KEY (uid) REFERENCES members(uid));")
+              ", UNIQUE (" +
+              ','.join(f'`{k}`' for k in tableMapping['transactions'].keys()) +
+              "), FOREIGN KEY (uid) REFERENCES members(uid));")
               #-- FOREIGN KEY event_id REFERENCES event eid
 
     c.execute("""CREATE TABLE IF NOT EXISTS labels (
diff --git a/tableMapping.yaml b/tableMapping.yaml
index 0ad28c9..8e26562 100644
--- a/tableMapping.yaml
+++ b/tableMapping.yaml
@@ -78,9 +78,8 @@ members:
 transactions:
   'sid': {type: CHAR(27)}
   'uid': {type: CHAR(24)}
-  # TODO: this is a terrible PK
-  'timestamp': {type: 'INT(11) PRIMARY KEY', source: '_dp'} # TODO: should be a real timestamp?
-  'type': {source: 'Transaction Type'}
+  'timestamp': {type: 'INT(11)', source: '_dp'} # TODO: should be a real timestamp?
+  'type': {type: 'VARCHAR(24)', source: 'Transaction Type'}
   'sum': {type: 'DECIMAL(13,4)'}
   'fee': {type: 'DECIMAL(13,4)'}
   'event_id': {source: 'eid'}