diff --git a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/Coalesce.java b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/Coalesce.java
new file mode 100644
index 000000000..78eb52446
--- /dev/null
+++ b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/Coalesce.java
@@ -0,0 +1,96 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.kernel.exps;
+
+import org.apache.openjpa.kernel.Filters;
+import org.apache.openjpa.kernel.StoreContext;
+
+/**
+ * An in-memory representation of a coalesce expression
+ *
+ * @author Catalina Wei
+ */
+public class Coalesce 
+    extends Val {
+
+    private final Val[] _val;
+
+    /**
+     * Constructor.
+     */
+    Coalesce(Val[] val) {
+        _val = val;
+    }
+
+    @Override
+    protected Object eval(Object candidate, Object orig, StoreContext ctx,
+        Object[] params) {
+        for (int i = 0; i < _val.length-1; i++) {
+            Object o1 = _val[i].eval(candidate, orig, ctx, params);
+            if (o1 != null)
+               return o1;
+           else
+               continue;
+        }
+        return _val[_val.length-1].eval(candidate, orig, ctx, params);
+    }
+
+    protected Object eval(Object candidate, StoreContext ctx,
+        Object[] params) {
+        for (int i = 0; i < _val.length-1; i++) {
+            Object o1 = _val[i].eval(candidate, null, ctx, params);
+            if (o1 != null)
+               return o1;
+           else
+               continue;
+        }
+        return _val[_val.length-1].eval(candidate, null, ctx, params);
+    }
+
+    /**
+     * Compare the two values.
+     */
+    protected boolean compare(Object o1, Object o2) {
+        return (o1 == null && o2 == null)
+            || (o1 != null && o1.equals(o2));
+    }
+
+    public Val[] getVal() {
+        return _val;
+    }
+
+    public Class getType() {
+        Class c1 = _val[0].getType();
+        for (int i = 1; i < _val.length; i++) {
+            Class c2 = _val[i].getType();
+            c1 = Filters.promote(c1, c2);
+        }
+        return c1;
+    }
+
+    public void setImplicitType(Class type) {       
+    }
+
+    public void acceptVisit(ExpressionVisitor visitor) {
+        visitor.enter(this);
+        for (int i = 0; i < _val.length; i++)
+            _val[i].acceptVisit(visitor);
+        visitor.exit(this);
+    }
+}
diff --git a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/GeneralCase.java b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/GeneralCase.java
new file mode 100644
index 000000000..f6231eef0
--- /dev/null
+++ b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/GeneralCase.java
@@ -0,0 +1,94 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.kernel.exps;
+
+import org.apache.openjpa.kernel.Filters;
+import org.apache.openjpa.kernel.StoreContext;
+import org.apache.openjpa.lib.util.Localizer;
+
+/**
+ * An in-memory representation of a general case expression
+ *
+ * @author Catalina Wei
+ */
+class GeneralCase
+    extends Val {
+
+    private static final Localizer _loc = Localizer.forPackage(
+        GeneralCase.class);
+
+    private final Exp[] _exp;
+    private final Val _val;
+
+    public GeneralCase(Exp[] exp, Val val) {
+        _exp = exp;
+        _val = val;
+    }
+
+    protected Object eval(Object candidate, Object orig, StoreContext ctx,
+        Object[] params) {
+        for (int i = 0; i < _exp.length; i++) {
+            boolean compare = ((WhenCondition) _exp[i]).getExp().
+                eval(candidate, orig, ctx, params);
+            
+            if (compare)
+                return ((WhenCondition) _exp[i]).getVal().
+                    eval(candidate, orig, ctx, params);
+            else
+                continue;
+        }
+        return _val.eval(candidate, orig, ctx, params);
+    }
+
+    protected Object eval(Object candidate,StoreContext ctx,
+        Object[] params) {
+
+        for (int i = 0; i < _exp.length; i++) {
+            boolean compare = ((WhenCondition) _exp[i]).getExp().
+                eval(candidate, null, ctx, params);
+                
+            if (compare)
+                return ((WhenCondition) _exp[i]).getVal().
+                    eval(candidate, null, ctx, params);
+            else
+                continue;
+        }
+        return _val.eval(candidate, null, ctx, params);
+    }
+
+    public Class getType() {
+        Class c1 = _val.getType();
+        for (int i = 0; i < _exp.length; i++) {
+            Class c2 = ((WhenCondition) _exp[i]).getVal().getType();
+            c1 = Filters.promote(c1, c2);
+        }
+        return c1;
+    }
+
+    public void setImplicitType(Class type) {
+    }
+
+    public void acceptVisit(ExpressionVisitor visitor) {
+        visitor.enter(this);
+        for (int i = 0; i < _exp.length; i++)
+            _exp[i].acceptVisit(visitor);
+        _val.acceptVisit(visitor);
+        visitor.exit(this);
+    }
+}
diff --git a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/InMemoryExpressionFactory.java b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/InMemoryExpressionFactory.java
index 653fbd9fc..1ccfea0e8 100644
--- a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/InMemoryExpressionFactory.java
+++ b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/InMemoryExpressionFactory.java
@@ -727,32 +727,36 @@ public class InMemoryExpressionFactory
 	}
 
     public Value generalCaseExpression(Expression[] exp, Value val) {
-        // TODO Auto-generated method stub
-        return null;
+        Exp[] exps = new Exp[exp.length];
+        for (int i = 0; i < exp.length; i++)
+            exps[i] = (Exp) exp[i];
+        return new GeneralCase(exps, (Val) val);
     }
 
-    public Value simpleCaseExpression(Value caseOperand, Expression[] exp, Value val) {
-        // TODO Auto-generated method stub
-        return null;
+    public Value simpleCaseExpression(Value caseOperand, Expression[] exp,
+        Value val) {
+            Exp[] exps = new Exp[exp.length];
+            for (int i = 0; i < exp.length; i++)
+                exps[i] = (Exp) exp[i];
+            return new SimpleCase((Val) caseOperand, exps, (Val) val);
     }
 
     public Expression whenCondition(Expression exp, Value val) {
-        // TODO Auto-generated method stub
-        return null;
+        return new WhenCondition((Exp) exp, (Val) val);
     }
 
     public Expression whenScalar(Value val1, Value val2) {
-        // TODO Auto-generated method stub
-        return null;
+        return new WhenScalar((Val) val1, (Val) val2);
     }
 
     public Value coalesceExpression(Value[] val) {
-        // TODO Auto-generated method stub
-        return null;
+        Val[] vals = new Val[val.length];
+        for (int i = 0; i < val.length; i++)
+            vals[i] = (Val) val[i];
+        return new Coalesce(vals);
     }
 
     public Value nullIfExpression(Value val1, Value val2) {
-        // TODO Auto-generated method stub
-        return null;
+        return new NullIf((Val) val1, (Val) val2);
     }
 }
diff --git a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/NullIf.java b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/NullIf.java
new file mode 100644
index 000000000..d9f6d6e4a
--- /dev/null
+++ b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/NullIf.java
@@ -0,0 +1,103 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.kernel.exps;
+
+import org.apache.openjpa.kernel.Filters;
+import org.apache.openjpa.kernel.StoreContext;
+
+/**
+ * An in-memory representation of a nullif expression
+ *
+ * @author Catalina Wei
+ */
+public class NullIf 
+    extends Val {
+
+    private final Val _val1;
+    private final Val _val2;
+
+    /**
+     * Constructor.
+     */
+    NullIf(Val val1, Val val2) {
+        _val1 = val1;
+        _val2 = val2;
+    }
+
+    @Override
+    protected Object eval(Object candidate, Object orig, StoreContext ctx,
+        Object[] params) {
+        Object o1 = _val1.eval(candidate, orig, ctx, params);
+        Object o2 = _val2.eval(candidate, orig, ctx, params);
+        if (o1 != null && o2 != null) {
+            Class c = Filters.promote(o1.getClass(), o2.getClass());
+            o1 = Filters.convert(o1, c);
+            o2 = Filters.convert(o2, c);
+        }
+        if (compare(o1, o2))
+            return null;
+        else
+            return o1;        
+    }
+
+    protected Object eval(Object candidate, StoreContext ctx,
+            Object[] params) {
+        Object o1 = _val1.eval(candidate, null, ctx, params);
+        Object o2 = _val2.eval(candidate, null, ctx, params);
+        if (o1 != null && o2 != null) {
+            Class c = Filters.promote(o1.getClass(), o2.getClass());
+            o1 = Filters.convert(o1, c);
+            o2 = Filters.convert(o2, c);
+        }
+        if (compare(o1, o2))
+            return null;
+        else
+            return o1;        
+    }
+
+    /**
+     * Compare the two values.
+     */
+    protected boolean compare(Object o1, Object o2) {
+        return (o1 == null && o2 == null)
+            || (o1 != null && o1.equals(o2));
+    }
+
+    public Val getVal1() {
+        return _val1;
+    }
+
+    public Val getVal2() {
+        return _val2;
+    }
+
+    public Class getType() {
+        return _val1.getType();
+    }
+
+    public void setImplicitType(Class type) {       
+    }
+
+    public void acceptVisit(ExpressionVisitor visitor) {
+        visitor.enter(this);
+        _val1.acceptVisit(visitor);
+        _val2.acceptVisit(visitor);
+        visitor.exit(this);
+    }
+}
diff --git a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/SimpleCase.java b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/SimpleCase.java
new file mode 100644
index 000000000..54dbe991f
--- /dev/null
+++ b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/SimpleCase.java
@@ -0,0 +1,91 @@
+package org.apache.openjpa.kernel.exps;
+
+import org.apache.openjpa.kernel.Filters;
+import org.apache.openjpa.kernel.StoreContext;
+
+/**
+ * An in-memory representation of a simple case expression
+ *
+ * @author Catalina Wei
+ */
+public class SimpleCase extends Val {
+    private final Val _caseOperand;
+    private final Exp[] _exp;
+    private final Val _val;
+
+    SimpleCase(Val caseOperand, Exp[] exp, Val val) {
+        _caseOperand = caseOperand;
+        _exp = exp;
+        _val = val;
+    }
+
+    @Override
+    protected Object eval(Object candidate, Object orig, StoreContext ctx,
+        Object[] params) {
+        Object o1 = _caseOperand.eval(candidate, orig, ctx, params);
+        for (int i = 0; i < _exp.length; i++) {
+            Object o2 = ((WhenScalar) _exp[i]).getVal1().
+                eval(candidate, orig, ctx, params);
+            if (o1 != null && o2 != null) {
+                Class c = Filters.promote(o1.getClass(), o2.getClass());
+                o1 = Filters.convert(o1, c);
+                o2 = Filters.convert(o2, c);
+            }
+            if (compare(o1, o2))
+                return ((WhenScalar) _exp[i]).getVal2().
+                    eval(candidate, orig, ctx, params);
+            else
+                continue;
+        }
+        return _val.eval(candidate, orig, ctx, params);
+    }
+
+    protected Object eval(Object candidate,StoreContext ctx,
+            Object[] params) {
+        Object o1 = _caseOperand.eval(candidate, null, ctx, params);
+        for (int i = 0; i < _exp.length; i++) {
+            Object o2 = ((WhenScalar) _exp[i]).getVal1().
+                eval(candidate, null, ctx, params);
+            if (o1 != null && o2 != null) {
+                Class c = Filters.promote(o1.getClass(), o2.getClass());
+                o1 = Filters.convert(o1, c);
+                o2 = Filters.convert(o2, c);
+            }
+            if (compare(o1, o2))
+                return ((WhenScalar) _exp[i]).getVal2().
+                    eval(candidate, null, ctx, params);
+            else
+                continue;
+        }
+        return _val.eval(candidate, null, ctx, params);
+    }
+
+    /**
+     * Compare the two values.
+     */
+    protected boolean compare(Object o1, Object o2) {
+        return (o1 == null && o2 == null)
+            || (o1 != null && o1.equals(o2));
+    }
+
+    public Class getType() {
+        Class c1 = _val.getType();
+        for (int i = 0; i < _exp.length; i++) {
+            Class c2 = ((WhenScalar) _exp[i]).getVal1().getType();
+            c1 = Filters.promote(c1, c2);
+        }
+        return c1;
+    }
+
+    public void setImplicitType(Class type) {       
+    }
+
+    public void acceptVisit(ExpressionVisitor visitor) {
+        visitor.enter(this);
+        _caseOperand.acceptVisit(visitor);
+        for (int i = 0; i < _exp.length; i++)
+            _exp[i].acceptVisit(visitor);
+        _val.acceptVisit(visitor);
+        visitor.exit(this);
+    }
+}
diff --git a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/WhenCondition.java b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/WhenCondition.java
new file mode 100644
index 000000000..a2cbb3c6f
--- /dev/null
+++ b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/WhenCondition.java
@@ -0,0 +1,49 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.kernel.exps;
+
+public class WhenCondition 
+    extends Exp {
+
+    private final Exp _exp;
+    private final Val _val;
+
+    /**
+     * Constructor.
+     */
+    WhenCondition(Exp exp, Val val) {
+        _exp = exp;
+        _val = val;
+    }
+
+    public Exp getExp() {
+        return _exp;
+    }
+
+    public Val getVal() {
+        return _val;
+    }
+
+    public void acceptVisit(ExpressionVisitor visitor) {
+        visitor.enter(this);
+        _exp.acceptVisit(visitor);
+        _val.acceptVisit(visitor);
+        visitor.exit(this);
+    }
+}
diff --git a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/WhenScalar.java b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/WhenScalar.java
new file mode 100644
index 000000000..560247d01
--- /dev/null
+++ b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/WhenScalar.java
@@ -0,0 +1,49 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.kernel.exps;
+
+public class WhenScalar 
+    extends Exp {
+
+    private final Val _val1;
+    private final Val _val2;
+
+    /**
+     * Constructor.
+     */
+    WhenScalar(Val val1, Val val2) {
+        _val1 = val1;
+        _val2 = val2;
+    }
+
+    public Val getVal1() {
+        return _val1;
+    }
+
+    public Val getVal2() {
+        return _val2;
+    }
+
+    public void acceptVisit(ExpressionVisitor visitor) {
+        visitor.enter(this);
+        _val1.acceptVisit(visitor);
+        _val2.acceptVisit(visitor);
+        visitor.exit(this);
+    }
+}