SQL Guidelines

Table names

1. Table names must begin with the PrestaShop "_DB_PREFIX_" prefix.

   ... FROM `'. _DB_PREFIX_.'customer` ...

2. Table names must have the same name as the object they reflect: "ps_cart".

3. Table names have to stay singular: "ps_order".

4. Language data have to be stored in a table named exactly like the object's table, and with the "_lang" suffix: "ps_product_lang".

SQL query

1. Keywords must be written in uppercase.

   SELECT `firstname`
   FROM `'._DB_PREFIX_.'customer`

2. Back quotes ("`") must be used around SQL field names and table names.

   SELECT p.`foo`, c.`bar`
   FROM `'._DB_PREFIX_.'product` p, `'._DB_PREFIX_.'customer` c

3. Table aliases have to be named by taking the first letter of each word, and must be lowercase.

   SELECT p.`id_product`, pl.`name`
   FROM `'._DB_PREFIX_.'product` p
   NATURAL JOIN `'._DB_PREFIX_.'product_lang` pl

4. When conflicts between table aliases occur, the second character has to be also used in the name.

   SELECT ca.`id_product`, cu.`firstname`
   FROM `'._DB_PREFIX_.'cart` ca, `'._DB_PREFIX_.'customer` cu

5. A new line has to be created for each clause.

   $query = 'SELECT pl.`name`
   FROM `'._DB_PREFIX_.'product_lang` pl
   WHERE pl.`id_product` = 17';

6. It is forbidden to make a JOIN in a WHERE clause.