Optimized code for database-sqlsever. (#7719)

Author: limingxinleo

src/Connection.php

@@ -977,6 +977,9 @@ public function setTablePrefix(string $prefix): static
 
     /**
      * Set the table prefix and return the grammar.
+     * @template T of Grammar
+     * @param T $grammar
+     * @return T
      */
     public function withTablePrefix(Grammar $grammar): Grammar
     {

src/Query/Builder.php

@@ -124,10 +124,8 @@ class Builder
 
     /**
      * The table joins for the query.
-     *
-     * @var array
      */
-    public $joins;
+    public ?array $joins = null;
 
     /**
      * The where constraints for the query.
@@ -1273,7 +1271,7 @@ public function orWhereYear($column, $operator, $value = null)
      * Add a nested where statement to the query.
      *
      * @param string $boolean
-     * @return Builder|static
+     * @return static
      */
     public function whereNested(Closure $callback, $boolean = 'and')
     {