Index: openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/StringLength.java
===================================================================
--- openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/StringLength.java	(revision 566297)
+++ openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/StringLength.java	(working copy)
@@ -53,6 +53,8 @@
         SQLBuffer buf, int index) {
         DBDictionary dict = ctx.store.getDBDictionary();
         String func = dict.stringLengthFunction;
+        if (getValue() instanceof Lit || getValue() instanceof Param)
+            func = dict.addCastAsString(func, "{0}", " AS VARCHAR(1000))");
         dict.assertSupport(func != null, "StringLengthFunction");
 
         int idx = func.indexOf("{0}");
Index: openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/ToLowerCase.java
===================================================================
--- openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/ToLowerCase.java	(revision 566297)
+++ openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/ToLowerCase.java	(working copy)
@@ -42,6 +42,8 @@
 
         DBDictionary dict = ctx.store.getDBDictionary();
         String func = dict.toLowerCaseFunction;
+        if (getValue() instanceof Lit || getValue() instanceof Param)
+            func = dict.addCastAsString(func, "{0}", " AS VARCHAR(1000))");
         dict.assertSupport(func != null, "ToLowerCaseFunction");
 
         int idx = func.indexOf("{0}");
Index: openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/ToUpperCase.java
===================================================================
--- openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/ToUpperCase.java	(revision 566297)
+++ openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/ToUpperCase.java	(working copy)
@@ -42,6 +42,8 @@
 
         DBDictionary dict = ctx.store.getDBDictionary();
         String func = dict.toUpperCaseFunction;
+        if (getValue() instanceof Lit || getValue() instanceof Param)
+            func = dict.addCastAsString(func, "{0}", " AS VARCHAR(1000))");
         dict.assertSupport(func != null, "ToUpperCaseFunction");
 
         int idx = func.indexOf("{0}");
Index: openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/Trim.java
===================================================================
--- openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/Trim.java	(revision 566297)
+++ openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/Trim.java	(working copy)
@@ -152,6 +152,9 @@
             dict.assertSupport(func != null, "TrimTrailingFunction");
         }
 
+        if (_val instanceof Lit || _val instanceof Param)
+           func = dict.addCastAsString(func, "{0}", " AS VARCHAR(1000))");
+
         int fromPart = func.indexOf("{0}");
         int charPart = func.indexOf("{1}");
         if (charPart == -1)
Index: openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/UnaryOp.java
===================================================================
--- openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/UnaryOp.java	(revision 566297)
+++ openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/UnaryOp.java	(working copy)
@@ -125,6 +125,7 @@
         sql.append(getOperator());
         sql.append("(");
         _val.appendTo(sel, ctx, state, sql, 0);
+        sql.addCastForParam(getOperator(), _val);
         sql.append(")");
     }
 
Index: openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/AbstractDB2Dictionary.java
===================================================================
--- openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/AbstractDB2Dictionary.java	(revision 566297)
+++ openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/AbstractDB2Dictionary.java	(working copy)
@@ -19,6 +19,8 @@
 package org.apache.openjpa.jdbc.sql;
 
 import org.apache.openjpa.jdbc.kernel.exps.FilterValue;
+import org.apache.openjpa.jdbc.kernel.exps.Val;
+import org.apache.openjpa.meta.JavaTypes;
 
 /**
  * Base dictionary for the IBM DB2 family of databases.
@@ -36,9 +38,9 @@
 
         // DB2-based databases have restrictions on having uncast parameters
         // in string functions
-        toUpperCaseFunction = "UPPER(CAST({0} AS VARCHAR(1000)))";
-        toLowerCaseFunction = "LOWER(CAST({0} AS VARCHAR(1000)))";
-        stringLengthFunction = "LENGTH(CAST({0} AS VARCHAR(1000)))";
+        toUpperCaseFunction = "UPPER({0})";
+        toLowerCaseFunction = "LOWER({0})";
+        stringLengthFunction = "LENGTH({0})";
         concatenateFunction = "(CAST({0} AS VARCHAR(1000)))||"
             + "(CAST({1} AS VARCHAR(1000)))";
 
@@ -100,5 +102,33 @@
             buf.append(") AS INTEGER)");
         }
         buf.append(")");
+    }    
+
+    /**
+     * add CAST for a scalar function where operand is a param
+     * @param func original string
+     * @param target string to look for
+     * @param asString
+     * @return
+     */
+    public String addCastAsString(String func, String target, String asString) {
+        String fstring = func;
+        if (func.indexOf(target) != -1)
+            fstring = func.replace(target, "CAST(" + target + asString);
+        return fstring;
+    }
+
+    /**
+     * add CAST for a function operator where operand is a param
+     * @param func function name
+     * @param val 
+     * @return
+     */
+    public String addCastAsType(String func, Val val) {
+        String fstring = null;
+        String type = getTypeName(getJDBCType(JavaTypes.getTypeCode(                  
+                val.getType()), false));
+        fstring = "CAST(? AS " + type + ")";
+        return fstring;
     }
 }
Index: openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/DBDictionary.java
===================================================================
--- openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/DBDictionary.java	(revision 566297)
+++ openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/DBDictionary.java	(working copy)
@@ -92,7 +92,6 @@
 import org.apache.openjpa.lib.log.Log;
 import org.apache.openjpa.lib.util.Localizer;
 import org.apache.openjpa.lib.util.Localizer.Message;
-import org.apache.openjpa.meta.FieldMetaData;
 import org.apache.openjpa.meta.JavaTypes;
 import org.apache.openjpa.util.GeneralException;
 import org.apache.openjpa.util.OpenJPAException;
@@ -2541,6 +2540,28 @@
     protected void appendLength(SQLBuffer buf, int type) {        
     }
 
+    /**
+     * add CAST for a scalar function where operand is a param
+     * @param func  original string
+     * @param target string to look for
+     * @param asString
+     * @return
+     */
+    public String addCastAsString(String func, String target, String asString) {
+        return func;
+    }
+    
+    /**
+     * add CAST for a function operator where operand is a param
+     * @param func  function name
+     * @param val 
+     * @return
+     */
+    public String addCastAsType(String func, Val val) {
+        return null;
+    }    
+
+
     ///////////
     // DDL SQL
     ///////////
Index: openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/SQLBuffer.java
===================================================================
--- openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/SQLBuffer.java	(revision 566324)
+++ openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/SQLBuffer.java	(working copy)
@@ -31,6 +31,7 @@
 
 import org.apache.commons.lang.ObjectUtils;
 import org.apache.openjpa.jdbc.kernel.JDBCFetchConfiguration;
+import org.apache.openjpa.jdbc.kernel.exps.Val;
 import org.apache.openjpa.jdbc.schema.Column;
 import org.apache.openjpa.jdbc.schema.Sequence;
 import org.apache.openjpa.jdbc.schema.Table;
@@ -593,6 +594,19 @@
     }
 
     /**
+     * Replace SQL '?' with CAST string if required by DB platform
+     * @param oper
+     * @param val
+     */
+    public void addCastForParam(String oper, Val val) {
+        if (_sql.charAt(_sql.length()-1) == '?') {
+            String castString = _dict.addCastAsType(oper, val);
+            if (castString != null)
+                _sql.replace(_sql.length()-1, _sql.length(), castString);
+        }
+    }
+
+    /**
      * Represents a subselect.
      */
     private static class Subselect {