[#5623] Add Name.first() and Name.last()

jOOQ/src/main/java/org/jooq/Name.java

@@ -71,6 +71,16 @@ import org.jooq.conf.Settings;
  */
 public interface Name extends QueryPart {
 
+    /**
+     * Get the first segment of the qualified name (usually a {@link Catalog} or {@link Schema} name).
+     */
+    String first();
+
+    /**
+     * Get the last segment of the qualified name (usually a {@link Table}, {@link Field}, or {@link Parameter} name).
+     */
+    String last();
+
     /**
      * The qualified name of this SQL identifier.
      */

jOOQ/src/main/java/org/jooq/impl/NameImpl.java

@@ -90,7 +90,7 @@ final class NameImpl extends AbstractQueryPart implements Name {
             }
         }
         else {
-            ctx.literal(qualifiedName[qualifiedName.length - 1]);
+            ctx.literal(last());
         }
     }
 
@@ -99,6 +99,24 @@ final class NameImpl extends AbstractQueryPart implements Name {
         return null;
     }
 
+    @Override
+    public final String first() {
+        for (int i = 0; i < qualifiedName.length; i++)
+            if (qualifiedName[i] != null)
+                return qualifiedName[i];
+
+        return null;
+    }
+
+    @Override
+    public final String last() {
+        for (int i = qualifiedName.length - 1; i >= 0; i--)
+            if (qualifiedName[i] != null)
+                return qualifiedName[i];
+
+        return null;
+    }
+
     @Override
     public final String[] getName() {
         return qualifiedName;
@@ -120,7 +138,7 @@ final class NameImpl extends AbstractQueryPart implements Name {
         if (qualifiedName.length != 1)
             throw new IllegalStateException("Cannot create a DerivedColumnList from a qualified name : " + Arrays.asList(qualifiedName));
 
-        return new DerivedColumnListImpl(qualifiedName[0], fieldNames);
+        return new DerivedColumnListImpl(first(), fieldNames);
     }
 
 
@@ -132,7 +150,7 @@ final class NameImpl extends AbstractQueryPart implements Name {
 
     @Override
     public final DerivedColumnListImpl fields(BiFunction<? super Field<?>, ? super Integer, ? extends String> fieldNameFunction) {
-        return new DerivedColumnListImpl(qualifiedName[0], fieldNameFunction);
+        return new DerivedColumnListImpl(first(), fieldNameFunction);
     }