Questions tagged as 'indices'

Is it possible to create an index in mysql but the index field is a substring? For example: Create NON-UNIQUE INDEX nombreInidice on nombreTabla (SUBSTRING(nombreCampo FROM 1 FOR 4)) USING HASH;     

I do not understand what is wrong with this code //$expense_categories = explode(chr(13), $row[expense_categories]); $categoryResult=mysqli_query($db,"SELECT category_id,category FROM expense_categories order by category_id"); if(mysqli_num_ro...

My problem is this, I have a code that apparently is fine. What I try to do is join 2 indexes located in 2 folders. The code is as follows public static void addIndices(String indexPath, boolean create) throws IOException { Analyzer an...

I have a foreach () that in each iteration adds arrays of 40 elements to another array, as shown in the following code: foreach($aVideos as $aVideo) { $aVideosReproducciones[] = $this->obtenerReproducciones($aVideos); } Assuming th...

How optimal is it to create an index for the fields used in the WHERE of the UPDATE and DELETE statements? I have researched on the subject and in general I find split opinions, in general the penalty is mentioned for all the sentences that are...

Hello to everyone at StackOverflow !! I hope you are well. Regarding my query, I would appreciate knowing what is the advantage of using Indices-I understand I can have up to 250 per table-in my SQL tables and if there are cases in which they...