[zendframework/zendframework#5857] Better logic for resetting select

- Reset the select object whenever any of the various setters are called that
  could modify the behavior of the select.

src/Db/AbstractDb.php

@@ -189,6 +189,7 @@ public function getExclude()
     public function setExclude($exclude)
     {
         $this->exclude = $exclude;
+        $this->select  = null;
         return $this;
     }
 
@@ -210,7 +211,8 @@ public function getField()
      */
     public function setField($field)
     {
-        $this->field = (string) $field;
+        $this->field  = (string) $field;
+        $this->select = null;
         return $this;
     }
 
@@ -232,7 +234,8 @@ public function getTable()
      */
     public function setTable($table)
     {
-        $this->table = (string) $table;
+        $this->table  = (string) $table;
+        $this->select = null;
         return $this;
     }
 
@@ -255,6 +258,7 @@ public function getSchema()
     public function setSchema($schema)
     {
         $this->schema = $schema;
+        $this->select = null;
         return $this;
     }
 
@@ -280,8 +284,7 @@ public function setSelect(Select $select)
      */
     public function getSelect()
     {
-        if ($this->select instanceof Select
-            && ($this->getSchema() === null || $this->getTable() === '' || $this->getField() === '' || $this->getExclude() === null)) {
+        if ($this->select instanceof Select) {
             return $this->select;
         }