SQL Naming Conventions (2024 Tutorial & Examples) (2024)

FAQs

What is the proper naming convention in SQL? ›

Database names must follow these rules: They must be unique within an installation. They must begin with an alphabetic character (not the underscore). No special characters other than the underscore, dollar sign, and at symbol (@) are allowed for regular identifiers.

Examples of naming conventions may include: Children's names may be alphabetical by birth order. In some Asian cultures, siblings commonly share a middle name. In many cultures the son is usually named after the father or grandfather.

A primary key is a field or a set of fields in the database table that uniquely identifies records in the database table. A table can have only one primary key. The naming conventions for a primary key constraint should have a "PK_" prefix, followed by the table name. The syntax should be "PK_<TableName>".

Since each foreign key value must exactly match the corresponding primary key value, the foreign key must contain the same number and data type of columns as the primary key, and these key columns must be in the same order. A foreign key can also have different column names than the primary key.

There are also a number of conventions which are enforced by the SQL engine. Though these vary somewhat between SQL “flavors”, SQL columns and table names should begin with a letter, not end in an underscore, and should contain only alphanumeric characters. Column and table names should not contain spaces.

Should SQL table names be singular or plural? ›

So Which Should I Use: Singular or Plural? The correct answer is that there is no right or wrong when naming database tables — just be consistent from the start. The only wrong answer with database table names is to use a combination of plural and singular.

SQL Table Letter-casing Conventions. For table names, you may use PascalCasing ( camelCasing with the first letter also capitalized) or lowercasing conventions, as long as you are consistent. In either case, table names should only contain alphabetic characters (no "_" or "-").

Object names should be full English words. In general avoid abbreviations, especially if they're just the type that removes vowels. Most SQL databases support at least 30-character names which should be more than enough for a couple English words. PostgreSQL supports up to 63-character for identifiers.

MySQL, Oracle, PostgreSQL, Microsoft SQL Server, MongoDB, Redis, Elasticsearch, Cassandra, MariaDB, IBM Db2.

Instance names are limited to 16 characters. The first character in the instance name must be a letter. Acceptable letters are the ones defined by the Unicode Standard 2.0. These letters include Latin characters a-z, A-Z, and letter characters from other languages.

For SQL naming, the qualified form is a schema-name followed by a period (.) and an SQL identifier. For system naming, the qualified form is a schema-name followed by a slash (/) followed by an SQL identifier¹. The unqualified form of a view-name is an SQL identifier.

A variable name can only contain alpha-numeric characters and underscores ( a-z, A-Z , 0-9 , and _ ) Variable names are case-sensitive (age, Age and AGE are three different variables) There is no limit on the length of the variable name. A variable name cannot contain spaces.