[5.4] Can't Wrap DB Names Containing Spaces When Aliasing (#17312)

* Can't Wrap DB Names Containing Spaces When Aliasing

Database names containing spaces are perfectly legal in Microsoft SQL Server.

Currently, when using SQL Server, if you have a database which includes spaces, the grammar handles wrapping it fine.

So this:

My Sample Database.dbo.my_table.my_column

Correctly becomes:

[My Sample Database].[dbo].[my_table].[my_column]

*But* if you also try to alias a column when the database contains spaces, it breaks.

This:

My Sample Database.dbo.my_table.my_column AS my_aliased_column

Becomes:

[My] AS [Sample]

I have traced the error to Database/Grammar/wrapAliasedValue() using explode( ' ' ) - the code thinks the spaces in the database name are the spaces around the "AS".

We can fix this by using regex instead of explode, splitting on the "AS" more accurately.

Just replace the explode with this:

$segments = preg_split( '/\s+as\s+/i', $value );

Note: When you have an Eloquent belongsToMany method that has to include the database name (eg. we need to join across DBs), this type of alias is created automatically, generating this error.

I originally committed this to 5.3 (laravel/framework#17292) and was asked to commit here instead.

* Adding Tests

RE: laravel/framework#17312

Grammar.php

@@ -71,17 +71,17 @@ public function wrap($value, $prefixAlias = false)
      */
     protected function wrapAliasedValue($value, $prefixAlias = false)
     {
-        $segments = explode(' ', $value);
+        $segments = preg_split( '/\s+as\s+/i', $value );
 
         // If we are wrapping a table we need to prefix the alias with the table prefix
         // as well in order to generate proper syntax. If this is a column of course
         // no prefix is necessary. The condition will be true when from wrapTable.
         if ($prefixAlias) {
-            $segments[2] = $this->tablePrefix.$segments[2];
+            $segments[1] = $this->tablePrefix.$segments[1];
         }
 
         return $this->wrap(
-            $segments[0]).' as '.$this->wrapValue($segments[2]
+            $segments[0]).' as '.$this->wrapValue($segments[1]
         );
     }