Poor Naming Standards Presented by: Niño R. Ricon Alain Anuevo MIT Presented to Dr. Armando and to the class of Database Design

A. Database naming conventions The following types of database objects are discussed here: 1. Tables 2. Columns (incl. Primary, Foreign and Composite Keys) 3. Indexes 4. Constraints 5. Views 6. Stored Procedures 7. Triggers

ALL DATABASE OBJECTS Limit the name to 30 characters Use only letters or underscores Try to use underscore characters as little as possible Use a letter as the first character of the name Avoid abbreviations Avoid acronyms Makes the name readable Avoid using spaces in names even if the system allows it

1. TABLES Rule #1: Plural Names - This rule is applicable because tables are logical collections of one or more entities as records - just like collection classes are logical collections of one or more objects. Example: Customers instead of Customer UserRoles instead of UserRole

1. TABLES Rule #2: Prefixes- if used correctly, table prefixes can help you organize your tables into related groups or distinguish them from other unrelated tables ELSE they can cause you to have to type a lot of unnecessary characters. Example: for a healthcare application you might give your tables an "Hc" prefix so that all of the tables for that application would appear in alphabetized lists together.

1. TABLES Rule #3: Notation - For all parts of the table name, including prefixes, use Pascal Case. Using this notation will distinguish your table names from SQL keywords. Example: "SELECT CustomerId_Pk, CustomerName FROM MyAppGroupTable WHERE CustomerName = '%S'" shows the notation for the table name distinguishing it from the SQL keywords used in the query.

1. TABLES Rule #4: Special Characters The underscore character has a place in other object names but, not for tables Using Pascal Case for your table name allows for the upper-case letter to denote the first letter of a new word or name Do not use numbers in your table names Do not use spaces in your table names Example: PurchaseOrder instead of Purchase_Order SalesOrder instead of [sales order] SalesInventory instead of sales inventory 1

1. TABLES Rule #5: Abbreviations- avoid using abbreviations if possible. Example: Accounts instead of Accnts Hours instead of Hrs

1. TABLES Rule #6: Junction/Intersection Tables - its handle many to many relationships, should be named by concatenating the names of the tables that have a one to many relationship with the junction table. Example: You might have "Doctors" and "Patients" tables. Since doctors can have many patients and patients can have many doctors (specialists) you need a table to hold the data for those relationships in a junction table. This table should be named "DoctorsPatients". Since this convention can result in lengthy table names, abbreviations sometimes may be used at your discretion.

2. COLUMNS - Just like with naming tables, avoid using abbreviations, acronyms or special characters. All column names should use Pascal Case to distinguish them from SQL keywords. Rule #1: Identify Primary Key Fields- For fields that are the primary key for a table and uniquely identify each record in the table, the name should simply be “Id“ since, that's what it is - an identification field. Example: Customer table with primary key fields named ID

2. COLUMNS Rule #2: Foreign Key fields- it should have the exact same name as they do in the parent table where the field is the primary key - with one exception - the table name should be specified. Example: Customer table where primary key fields named ID and the foreign key is CustomerID from the Orders table.

2. COLUMNS Rule #3: Composite Keys- If you have tables with composite keys (more than one field makes up the unique value) then instead of just “Id“ you should use a descriptor before the “Id“ characters. Example: ID, ModuleID, CodeID

2. COLUMNS Rule #4: Prefixes- Do not prefix your fields with "fld_" or "Col_" as it should be obvious in SQL statements which items are columns (before or after the FROM clause). Including a two or three character data type prefix for the field is optional and not recommended, Example: "IntCustomerId" for a numeric type or "VcName" for a varchar type.

2. COLUMNS Rule #5: Data Type Specific Naming Example: Boolean data types = “IsDeleted” or ”HasPermission” Date/Time data types = “RuntimeHours” or “ScheduledMinutes”

3. INDEXES Rule #1: Naming Conventions Indexes Structure: {TableName}{ColumnsIndexed}{U/N}{C/N} where: U/N - Unique or Non-Unique C/N – Clustered or Non-Clustered Example: OrderDetailsOrderIdCustomerIdNN - indicates a non- unique, non-clustered index on the OrderId and CustomerId columns in the OrderDetails table.

3. INDEXES Rule #2: Prefixes and Suffixes Avoid "idx" or "IDX_" before your indexes. A suffix of "_idx" or "IDX" is not necessary.

4. CONSTRAINTS Rule #1: Naming Conventions Syntax: {constraint type}{table name}_{field name} Examples: 1. PkProducts_Id - primary key constraint on the Id field of the products table 2. FkOrders_ProductId - foreign key constraint on the productId field in the Orders table 3. CkCustomers_AccountRepId - check constraint on the accountRepId field in the Customers table

4. CONSTRAINTS Rule #2: Prefixes Primary Key: Pk Foreign Key: Fk Check: Ck Unique: Un

5. VIEWS Rule #1: Prefixes While it is pointless to prefix tables, it can be helpful for views. Prefixing your views with "Vw" or "View" is a helpful reminder that you're dealing with a view, and not a table. Whatever type of prefix you choose to apply, use at least 2 letters and not just "V" because a prefix should use more more than one letter or its meaning can be ambiguous.

5. VIEWS Rule #2: View Types For simple views that just join one or more tables with no selection criteria, combine the names of the tables joined. Example: Joining the "Customers" and "StatesAndProvinces" table to create a view of Customers and their respective geographical data should be given a name like "VwCustomersStatesAndProvinces".

6. STORED PROCEDURES Rule #1: Prefixes or Suffixes 1. Group by the type of CRUD operation Example: “CreateProductInfo” or “CreateOrder” 2. GRUD operation they perform Example: “ProductInfoCreate” or “OrdersCreate” 3. Performs an operation like validation, use the verb and noun combination Example: “ValidateLogin”

6. STORED PROCEDURES Rule #2: Grouping Prefixes If you have many stored procedures, you might want to consider using a grouping prefix that can be used to identify which parts of an application the stored procedure is used by. Example: "Prl" – Payroll related procedures "Hr" - Human Resources related procedures

6. STORED PROCEDURES Rule #3: Bad Prefixes Do not prefix your stored procedures with something that will cause the system to think it is a system procedure Example: "sp_", "xp_" or "dt_" – in SQL Server

7. TRIGGERS Rule #1: Prefixes/Suffixes To distinguish triggers from other database objects, it is helpful to add "Trg" as a prefix or suffix. Example: “ Trg_ProductsIns “, “ ProductsInsTrg “, “ Products_InsTrg” or InsProducts_Trg

7. TRIGGERS Rule #2: Multiple Operations If a trigger handles more than one operation (both INSERT and UPDATE for example) then include both operation abbreviations in your name. Example: "Products_InsUpdTrg" or "TrgProducts_UpdDel"

7. TRIGGERS Rule #3: Multiple Triggers Some systems allow multiple triggers per operation per table but make sure the names of these triggers are easy to distinguish. Example: "Users_Validate Address_InsTrg" "Users_MakeActionEntries_InsTrg".