Changes based on feedback form Noel Grandin

* Renamed enum NULL_CONSTRAINT to NullConstraintType
* Replaced some switches with if-statement
* Check for Oracle-Mode when parsing Oracles-SQLs NOT NULL ENABLE
VALIDATE syntax. NOTE: 
* Added DbTypeEnum-class to Mode to have a String-free dbType check
featuring the method Database.isDbTypeOneOf(DbTypeEnum... dbTypes)

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

@@ -18,6 +18,7 @@ import java.util.Comparator;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
+
 import org.h2.api.ErrorCode;
 import org.h2.api.Trigger;
 import org.h2.command.ddl.AlterIndexRename;
@@ -93,7 +94,7 @@ import org.h2.engine.Constants;
 import org.h2.engine.Database;
 import org.h2.engine.DbObject;
 import org.h2.engine.FunctionAlias;
-import org.h2.engine.Mode;
+import org.h2.engine.Mode.DbTypeEnum;
 import org.h2.engine.Procedure;
 import org.h2.engine.Right;
 import org.h2.engine.Session;
@@ -820,7 +821,7 @@ public class Parser {
         }
         currentPrepared = command;
         int start = lastParseIndex;
-        if (!readIf("FROM") && database.getMode() == Mode.getMySQL()) {
+        if (!readIf("FROM") && database.isDbTypeOneOf(DbTypeEnum.MySQL)) {
             readIdentifierWithSchema();
             read("FROM");
         }
@@ -4073,10 +4074,9 @@ public class Parser {
         } else if (readIf("VISIBLE")) {
             column.setVisible(true);
         }
-        NULL_CONSTRAINT nullConstraint = parseNotNullConstraint();
+        NullConstraintType nullConstraint = parseNotNullConstraint();
         switch (nullConstraint) {
         case NULL_IS_ALLOWED:
-
             column.setNullable(true);
             break;
         case NULL_IS_NOT_ALLOWED:
@@ -4121,13 +4121,8 @@ public class Parser {
             column.setPrimaryKey(true);
             column.setAutoIncrement(true, start, increment);
         }
-        nullConstraint = parseNotNullConstraint();
-        switch (nullConstraint) {
-        case NULL_IS_NOT_ALLOWED:
+        if (NullConstraintType.NULL_IS_NOT_ALLOWED == parseNotNullConstraint()) { 
             column.setNullable(false);
-            break;
-        default:
-            // do nothing
         }
         if (readIf("AUTO_INCREMENT") || readIf("BIGSERIAL") || readIf("SERIAL")) {
             parseAutoIncrement(column);
@@ -5876,7 +5871,7 @@ public class Parser {
             readIf("COLUMN"); // optional
             String columnName = readColumnIdentifier();
             AlterTableAlterColumn command = null;
-            NULL_CONSTRAINT nullConstraint = parseNotNullConstraint();
+            NullConstraintType nullConstraint = parseNotNullConstraint();
             switch (nullConstraint) {
             case NULL_IS_ALLOWED:
             case NULL_IS_NOT_ALLOWED:
@@ -5885,7 +5880,7 @@ public class Parser {
                 command.setIfTableExists(ifTableExists);
                 Column column = columnIfTableExists(schema, tableName, columnName, ifTableExists);
                 command.setOldColumn(column);
-                if (nullConstraint == NULL_CONSTRAINT.NULL_IS_ALLOWED) {
+                if (nullConstraint == NullConstraintType.NULL_IS_ALLOWED) {
                     command.setType(CommandInterface.ALTER_TABLE_ALTER_COLUMN_NULL);
                 } else {
                     command.setType(CommandInterface.ALTER_TABLE_ALTER_COLUMN_NOT_NULL);
@@ -5950,7 +5945,7 @@ public class Parser {
                 command.setTableName(tableName);
                 command.setIfTableExists(ifTableExists);
                 command.setOldColumn(column);
-                NULL_CONSTRAINT nullConstraint = parseNotNullConstraint();
+                NullConstraintType nullConstraint = parseNotNullConstraint();
                 switch (nullConstraint) {
                 case NULL_IS_ALLOWED:
                     command.setType(CommandInterface.ALTER_TABLE_ALTER_COLUMN_NULL);
@@ -6372,14 +6367,8 @@ public class Parser {
                             unique.setTableName(tableName);
                             command.addConstraintCommand(unique);
                         }
-
-                        NULL_CONSTRAINT nullConstraint = parseNotNullConstraint();
-                        switch (nullConstraint) {
-                        case NULL_IS_NOT_ALLOWED:
+                        if (NullConstraintType.NULL_IS_NOT_ALLOWED == parseNotNullConstraint()) {
                             column.setNullable(false);
-                            break;
-                        default:
-                            // do nothing
                         }
                         if (readIf("CHECK")) {
                             Expression expr = readExpression();
@@ -6482,32 +6471,34 @@ public class Parser {
         return command;
     }
 
-    private enum NULL_CONSTRAINT {
+    private enum NullConstraintType {
         NULL_IS_ALLOWED, NULL_IS_NOT_ALLOWED, NO_NULL_CONSTRAINT_FOUND
     }
 
-    private NULL_CONSTRAINT parseNotNullConstraint() {
-        NULL_CONSTRAINT nullConstraint = NULL_CONSTRAINT.NO_NULL_CONSTRAINT_FOUND;
+    private NullConstraintType parseNotNullConstraint() {
+        NullConstraintType nullConstraint = NullConstraintType.NO_NULL_CONSTRAINT_FOUND;
         if ((isToken("NOT") || isToken("NULL"))) {
             if (readIf("NOT")) {
                 read("NULL");
-                nullConstraint = NULL_CONSTRAINT.NULL_IS_NOT_ALLOWED;
+                nullConstraint = NullConstraintType.NULL_IS_NOT_ALLOWED;
             } else {
                 read("NULL");
-                nullConstraint = NULL_CONSTRAINT.NULL_IS_ALLOWED;
+                nullConstraint = NullConstraintType.NULL_IS_ALLOWED;
             }
+            if (database.isDbTypeOneOf(DbTypeEnum.Oracle)) {
                 if (readIf("ENABLE")) {
                     readIf("VALIDATE"); // Leave constraint 'as is'
-                if (readIf("NOVALIDATE")) { // Turn off constraint, thus allow NULLs
-                    nullConstraint = NULL_CONSTRAINT.NULL_IS_ALLOWED;
+                    if (readIf("NOVALIDATE")) { // Turn off constraint, allow NULLs
+                        nullConstraint = NullConstraintType.NULL_IS_ALLOWED;
                     }
                 }
-            if (readIf("DISABLE")) { // Turn off constraint, thus allow NULLs
-                nullConstraint = NULL_CONSTRAINT.NULL_IS_ALLOWED;
+                if (readIf("DISABLE")) { // Turn off constraint, allow NULLs
+                    nullConstraint = NullConstraintType.NULL_IS_ALLOWED;
                     readIf("VALIDATE"); // ignore validate
                     readIf("NOVALIDATE"); // ignore novalidate
                 }
             }
+        }
         return nullConstraint;
     }
 

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

@@ -18,6 +18,7 @@ import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.atomic.AtomicReference;
+
 import org.h2.api.DatabaseEventListener;
 import org.h2.api.ErrorCode;
 import org.h2.api.JavaObjectSerializer;
@@ -26,6 +27,7 @@ import org.h2.command.CommandInterface;
 import org.h2.command.ddl.CreateTableData;
 import org.h2.command.dml.SetTypes;
 import org.h2.constraint.Constraint;
+import org.h2.engine.Mode.DbTypeEnum;
 import org.h2.index.Cursor;
 import org.h2.index.Index;
 import org.h2.index.IndexType;
@@ -2376,6 +2378,16 @@ public class Database implements DataHandler {
         return mode;
     }
 
+    public boolean isDbTypeOneOf(DbTypeEnum... dbTypes) {
+        DbTypeEnum currentDbType = mode.getDbTypeEnum();
+        for (DbTypeEnum dbType : dbTypes) {
+            if (currentDbType == dbType) {
+                return true;
+            }
+        }
+        return false;
+    }
+    
     public boolean isMultiThreaded() {
         return multiThreaded;
     }

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

@@ -23,7 +23,25 @@ public class Mode {
      */
     static final String REGULAR = "REGULAR";
 
-    private static final HashMap<String, Mode> MODES = New.hashMap();
+    public static enum DbTypeEnum {
+        REGULAR, UNKNOWN, DB2 , Derby, HSQLDB, Ignite, MSSQLServer, MySQL, Oracle, PostgreSQL;
+    
+        public static DbTypeEnum parse(String modeAsStr) {
+            DbTypeEnum result = DbTypeEnum.UNKNOWN;
+            if (modeAsStr != null) {
+                modeAsStr = StringUtils.toUpperEnglish(modeAsStr.trim());
+                for (DbTypeEnum m: DbTypeEnum.values()) {
+                   if (m.name().toUpperCase().equals(modeAsStr)) {
+                       result = m;
+                       break;
+                   }
+                }
+            }
+            return result;
+        }    
+    }
+    
+    private static final HashMap<DbTypeEnum, Mode> MODES = New.hashMap();
 
     // Modes are also documented in the features section
 
@@ -178,14 +196,14 @@ public class Mode {
      */
     public Set<String> disallowedTypes = Collections.emptySet();
 
-    private final String name;
+    private final DbTypeEnum dbTypeEnum;
 
     static {
-        Mode mode = new Mode(REGULAR);
+        Mode mode = new Mode(DbTypeEnum.REGULAR);
         mode.nullConcatIsNull = true;
         add(mode);
 
-        mode = new Mode("DB2");
+        mode = new Mode(DbTypeEnum.DB2);
         mode.aliasColumnName = true;
         mode.supportOffsetFetch = true;
         mode.sysDummy1 = true;
@@ -200,7 +218,7 @@ public class Mode {
         mode.allowDB2TimestampFormat = true;
         add(mode);
 
-        mode = new Mode("Derby");
+        mode = new Mode(DbTypeEnum.Derby);
         mode.aliasColumnName = true;
         mode.uniqueIndexSingleNull = true;
         mode.supportOffsetFetch = true;
@@ -210,7 +228,7 @@ public class Mode {
         mode.supportedClientInfoPropertiesRegEx = null;
         add(mode);
 
-        mode = new Mode("HSQLDB");
+        mode = new Mode(DbTypeEnum.HSQLDB);
         mode.aliasColumnName = true;
         mode.convertOnlyToSmallerScale = true;
         mode.nullConcatIsNull = true;
@@ -223,7 +241,7 @@ public class Mode {
         mode.supportedClientInfoPropertiesRegEx = null;
         add(mode);
 
-        mode = new Mode("MSSQLServer");
+        mode = new Mode(DbTypeEnum.MSSQLServer);
         mode.aliasColumnName = true;
         mode.squareBracketQuotedNames = true;
         mode.uniqueIndexSingleNull = true;
@@ -235,7 +253,7 @@ public class Mode {
         mode.supportedClientInfoPropertiesRegEx = null;
         add(mode);
 
-        mode = new Mode("MySQL");
+        mode = new Mode(DbTypeEnum.MySQL);
         mode.convertInsertNullToZero = true;
         mode.indexDefinitionInCreateTable = true;
         mode.lowerCaseIdentifiers = true;
@@ -249,7 +267,7 @@ public class Mode {
         mode.prohibitEmptyInPredicate = true;
         add(mode);
 
-        mode = new Mode("Oracle");
+        mode = new Mode(DbTypeEnum.Oracle);
         mode.aliasColumnName = true;
         mode.convertOnlyToSmallerScale = true;
         mode.uniqueIndexSingleNullExceptAllColumnsAreNull = true;
@@ -262,7 +280,7 @@ public class Mode {
         mode.prohibitEmptyInPredicate = true;
         add(mode);
 
-        mode = new Mode("PostgreSQL");
+        mode = new Mode(DbTypeEnum.PostgreSQL);
         mode.aliasColumnName = true;
         mode.nullConcatIsNull = true;
         mode.supportOffsetFetch = true;
@@ -285,19 +303,19 @@ public class Mode {
         mode.disallowedTypes = disallowedTypes;
         add(mode);
 
-        mode = new Mode("Ignite");
+        mode = new Mode(DbTypeEnum.Ignite);
         mode.nullConcatIsNull = true;
         mode.allowAffinityKey = true;
         mode.indexDefinitionInCreateTable = true;
         add(mode);
     }
 
-    private Mode(String name) {
-        this.name = name;
+    private Mode(DbTypeEnum dbTypeEnum) {
+        this.dbTypeEnum = dbTypeEnum;
     }
 
     private static void add(Mode mode) {
-        MODES.put(StringUtils.toUpperEnglish(mode.name), mode);
+        MODES.put(mode.dbTypeEnum, mode);
     }
 
     /**
@@ -307,15 +325,24 @@ public class Mode {
      * @return the mode object
      */
     public static Mode getInstance(String name) {
-        return MODES.get(StringUtils.toUpperEnglish(name));
+        DbTypeEnum dbTypeEnum = DbTypeEnum.parse(name);
+        return MODES.get(dbTypeEnum);
+    }
+    
+    public static Mode getInstance(DbTypeEnum dbTypeEnum) {
+        return  MODES.get(dbTypeEnum);
     }
 
     public static Mode getMySQL() {
-        return getInstance("MySQL");
+        return getInstance(DbTypeEnum.MySQL);
+    }
+    
+    public DbTypeEnum getDbTypeEnum() {
+        return dbTypeEnum;
     }
 
     public String getName() {
-        return name;
+        return dbTypeEnum.name();
     }
 
 }