PascalCase allows for tables to clearly identify their relationship within the Query collection hierarchies.
An exception can be made when naming junction tables. The use of underscores can be used to separate the table names from the relationship, as in Student_in_Class and Product_in_Category.
When columns are referenced in PHP using model classes, they are done so using object properties, so using camel case is consistent with how object properties are written and accessed across other repositories.
Most tables will use a single identifying column as the primary key. In this case, they should simple be named id, rather than other commonly used patterns such as id_customer, or customerId.
Database columns should be named using the same conventions as object properties, as when the database is loaded into PHP it will inevitably be represented by object properties.