How to Translate Complex MySQL Statements with PREPARE, EXECUTE, and DEALLOCATE into Laravel Eloquent?

Translating Complex MySQL Statements into Laravel Eloquent

Laravel Eloquent provides an elegant mechanism to execute SQL queries using expressive PHP code. However, converting complex multi-statement MySQL queries can be intimidating. This article guides you through transforming such queries into Eloquent, specifically addressing the challenges presented by statements like PREPARE, EXECUTE, SET, and DEALLOCATE.

Query Conversion Approach

To convert the provided MySQL query, we will predominantly use raw queries in Eloquent. Here's the breakdown:

DB::table('item_details')->selectRaw('GROUP_CONCAT(...) INTO @sql')->get();
DB::statement('SET @sql = CONCAT(...)');
DB::statement('PREPARE stmt FROM @sql');
DB::statement('EXECUTE stmt');
DB::statement('DEALLOCATE PREPARE stmt');

Converting these into Eloquent code, we get:

$result = DB::table('item_details')->selectRaw('GROUP_CONCAT(...) INTO @sql')->get();
$sql = DB::selectOne('select @sql')->{'@sql'};
$results = ItemDetails::select('item_number', DB::raw('SUM(quantity) as total_quantity'))->selectRaw($sql)->groupBy('item_number')->get();

This approach employs a series of raw queries to achieve the desired result. The initial query concatenates the desired SQL into a user variable @sql. Subsequently, PHP retrieves this variable using a separate query and then constructs an Eloquent query to execute the final SQL statement, which includes the concatenated SQL.

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