Trigger that are called before a select statement are now supported.

h2/src/main/org/h2/api/Trigger.java

@@ -29,6 +29,11 @@ public interface Trigger {
      */
     int DELETE = 4;
 
+    /**
+     * The trigger is called for SELECT statements.
+     */
+    int SELECT = 8;
+
     /**
      * This method is called by the database engine once when initializing the
      * trigger.

h2/src/main/org/h2/command/Parser.java

@@ -3707,6 +3707,8 @@ public class Parser {
                 typeMask |= Trigger.UPDATE;
             } else if (readIf("DELETE")) {
                 typeMask |= Trigger.DELETE;
+            } else if (readIf("SELECT")) {
+                typeMask |= Trigger.SELECT;
             } else {
                 throw getSyntaxError();
             }

h2/src/main/org/h2/command/dml/Query.java

@@ -177,6 +177,11 @@ public abstract class Query extends Prepared {
      */
     public abstract void updateAggregate(Session s) throws SQLException;
 
+    /**
+     * Call the before triggers on all tables.
+     */
+    public abstract void fireBeforeSelectTriggers() throws SQLException;
+
     public boolean isQuery() {
         return true;
     }
@@ -216,6 +221,7 @@ public abstract class Query extends Prepared {
     }
 
     public ResultInterface query(int limit) throws SQLException {
+        fireBeforeSelectTriggers();
         if (!session.getDatabase().getOptimizeReuseResults()) {
             return queryWithoutCache(limit);
         }

h2/src/main/org/h2/command/dml/Select.java

@@ -10,6 +10,7 @@ import java.sql.SQLException;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
+import org.h2.api.Trigger;
 import org.h2.constant.ErrorCode;
 import org.h2.constant.SysProperties;
 import org.h2.engine.Constants;
@@ -791,6 +792,12 @@ public class Select extends Query {
         return set;
     }
 
+    public void fireBeforeSelectTriggers() throws SQLException {
+        for (TableFilter filter : filters) {
+            filter.getTable().fire(session, Trigger.SELECT, true);
+        }
+    }
+
     private double preparePlan() throws SQLException {
         TableFilter[] topArray = topFilters.toArray(new TableFilter[topFilters.size()]);
         for (TableFilter t : topArray) {

h2/src/main/org/h2/command/dml/SelectUnion.java

@@ -353,4 +353,9 @@ public class SelectUnion extends Query {
         return null;
     }
 
+    public void fireBeforeSelectTriggers() throws SQLException {
+        left.fireBeforeSelectTriggers();
+        right.fireBeforeSelectTriggers();
+    }
+
 }

h2/src/main/org/h2/schema/TriggerObject.java

@@ -20,6 +20,7 @@ import org.h2.message.Trace;
 import org.h2.result.Row;
 import org.h2.table.Table;
 import org.h2.util.ClassUtils;
+import org.h2.util.StatementBuilder;
 import org.h2.value.DataType;
 import org.h2.value.Value;
 
@@ -96,15 +97,19 @@ public class TriggerObject extends SchemaObjectBase {
      * or after any rows have been processed, once for each statement.
      *
      * @param session the session
+     * @param type the trigger type
      * @param beforeAction if this method is called before applying the changes
      */
-    public void fire(Session session, boolean beforeAction) throws SQLException {
-        if (rowBased || before != beforeAction) {
+    public void fire(Session session, int type, boolean beforeAction) throws SQLException {
+        if (rowBased || before != beforeAction || (typeMask & type) == 0) {
             return;
         }
         load(session);
         Connection c2 = session.createConnection(false);
-        boolean old = session.setCommitOrRollbackDisabled(true);
+        boolean old = false;
+        if (type != Trigger.SELECT) {
+            old = session.setCommitOrRollbackDisabled(true);
+        }
         Value identity = session.getScopeIdentity();
         try {
             triggerCallback.fire(c2, null, null);
@@ -113,9 +118,11 @@ public class TriggerObject extends SchemaObjectBase {
                             triggerClassName, e.toString());
         } finally {
             session.setScopeIdentity(identity);
+            if (type != Trigger.SELECT) {
                 session.setCommitOrRollbackDisabled(old);
             }
         }
+    }
 
     private Object[] convertToObjectList(Row row) {
         if (row == null) {
@@ -256,22 +263,23 @@ public class TriggerObject extends SchemaObjectBase {
     }
 
     public String getTypeNameList() {
-        StringBuilder buff = new StringBuilder();
+        StatementBuilder buff = new StatementBuilder();
         if ((typeMask & Trigger.INSERT) != 0) {
+            buff.appendExceptFirst(", ");
             buff.append("INSERT");
         }
         if ((typeMask & Trigger.UPDATE) != 0) {
-            if (buff.length() > 0) {
-                buff.append(", ");
-            }
+            buff.appendExceptFirst(", ");
             buff.append("UPDATE");
         }
         if ((typeMask & Trigger.DELETE) != 0) {
-            if (buff.length() > 0) {
-                buff.append(", ");
-            }
+            buff.appendExceptFirst(", ");
             buff.append("DELETE");
         }
+        if ((typeMask & Trigger.SELECT) != 0) {
+            buff.appendExceptFirst(", ");
+            buff.append("SELECT");
+        }
         return buff.toString();
     }