CREATE DOMAIN: Built-in data types can now only be changed if no tables exist.

h2/src/main/org/h2/command/ddl/CreateUserDataType.java

@@ -14,6 +14,7 @@ import org.h2.engine.Session;
 import org.h2.engine.UserDataType;
 import org.h2.message.Message;
 import org.h2.table.Column;
+import org.h2.table.Table;
 import org.h2.value.DataType;
 
 /**
@@ -39,7 +40,6 @@ public class CreateUserDataType extends DefineCommand {
     }
 
     public void setIfNotExists(boolean ifNotExists) {
-        // TODO user data type: if exists - probably better use 'or replace'
         this.ifNotExists = ifNotExists;
     }
 
@@ -55,8 +55,14 @@ public class CreateUserDataType extends DefineCommand {
             throw Message.getSQLException(ErrorCode.USER_DATA_TYPE_ALREADY_EXISTS_1, typeName);
         }
         DataType builtIn = DataType.getTypeByName(typeName);
-        if (builtIn != null && !builtIn.hidden) {
-            throw Message.getSQLException(ErrorCode.USER_DATA_TYPE_ALREADY_EXISTS_1, typeName);
+        if (builtIn != null) {
+            if (!builtIn.hidden) {
+                throw Message.getSQLException(ErrorCode.USER_DATA_TYPE_ALREADY_EXISTS_1, typeName);
+            }
+            Table table = session.getDatabase().getFirstUserTable();
+            if (table != null) {
+                throw Message.getSQLException(ErrorCode.USER_DATA_TYPE_ALREADY_EXISTS_1, typeName + " (" + table.getSQL() + ")");
+            }
         }
         int id = getObjectId(false, true);
         UserDataType type = new UserDataType(db, id, typeName);

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

@@ -14,7 +14,6 @@ import org.h2.compress.Compressor;
 import org.h2.constant.ErrorCode;
 import org.h2.constant.SysProperties;
 import org.h2.engine.Database;
-import org.h2.engine.DbObject;
 import org.h2.engine.Mode;
 import org.h2.engine.Session;
 import org.h2.engine.Setting;
@@ -25,7 +24,6 @@ import org.h2.result.LocalResult;
 import org.h2.schema.Schema;
 import org.h2.table.Table;
 import org.h2.tools.CompressTool;
-import org.h2.util.ObjectArray;
 import org.h2.util.StringUtils;
 import org.h2.value.CompareMode;
 import org.h2.value.ValueInt;
@@ -94,12 +92,9 @@ public class Set extends Prepared {
         }
         case SetTypes.COLLATION: {
             session.getUser().checkAdmin();
-            ObjectArray array = database.getAllSchemaObjects(DbObject.TABLE_OR_VIEW);
-            for (int i = 0; i < array.size(); i++) {
-                Table table = (Table) array.get(i);
-                if (table.getCreateSQL() != null) {
-                    throw Message.getSQLException(ErrorCode.COLLATION_CHANGE_WITH_DATA_TABLE_1, table.getSQL());
-                }
+            Table table = database.getFirstUserTable();
+            if (table != null) {
+                throw Message.getSQLException(ErrorCode.COLLATION_CHANGE_WITH_DATA_TABLE_1, table.getSQL());
             }
             CompareMode compareMode;
             StringBuffer buff = new StringBuffer(stringValue);

h2/src/main/org/h2/engine/Database.java

@@ -2124,4 +2124,20 @@ public class Database implements DataHandler {
         }
     }
 
+    /**
+     * Get the first user defined table.
+     *
+     * @return the table or null if no table is defined
+     */
+    public Table getFirstUserTable() {
+        ObjectArray array = getAllSchemaObjects(DbObject.TABLE_OR_VIEW);
+        for (int i = 0; i < array.size(); i++) {
+            Table table = (Table) array.get(i);
+            if (table.getCreateSQL() != null) {
+                return table;
+            }
+        }
+        return null;
+    }
+
 }