Start Coding

Subjects

JAVASCRIPTHTMLCSSPYTHONSQLJAVACPPCSHARPPHPTYPESCRIPTCRUBYGOSWIFTKOTLINRUSTRBASHSCALAOBJECTIVE-CDARTPERLLUAMATLABXMLJSONMARKDOWNASSEMBLYLATEXYAMLSOLIDITYBLOCKCHAIN

Topics

Introduction to SQL

What is SQL?SQL HistorySQL StandardsSQL vs NoSQLSQL Database Management Systems

SQL Basics

SQL SyntaxSQL CommentsSQL Data TypesSQL OperatorsSQL ExpressionsSQL LiteralsSQL IdentifiersSQL KeywordsSQL Case Sensitivity

SQL Database Fundamentals

Database ConceptsTables and FieldsPrimary KeysForeign KeysIndexesConstraintsNormalizationDenormalizationSQL Schema Design

SQL Data Manipulation

SQL SELECT StatementSQL INSERT StatementSQL UPDATE StatementSQL DELETE StatementSQL MERGE StatementSQL AliasesSQL WildcardsSQL LIKE OperatorSQL IN OperatorSQL BETWEEN OperatorSQL NULL ValuesSQL ORDER BY ClauseSQL LIMIT ClauseSQL OFFSET Clause

SQL Filtering and Sorting

SQL WHERE ClauseSQL AND, OR, NOT OperatorsSQL GROUP BY ClauseSQL HAVING ClauseSQL DISTINCT KeywordSQL TOP Clause

SQL Joins

SQL INNER JOINSQL LEFT JOINSQL RIGHT JOINSQL FULL OUTER JOINSQL CROSS JOINSQL Self JOINSQL Natural JOINSQL Multiple JOINs

SQL Functions

SQL Aggregate FunctionsSQL Scalar FunctionsSQL String FunctionsSQL Numeric FunctionsSQL Date FunctionsSQL Conversion FunctionsSQL System FunctionsSQL User-Defined Functions

SQL Subqueries

SQL Subquery BasicsCorrelated SubqueriesNested SubqueriesSQL EXISTS OperatorSQL ANY and ALL OperatorsSubqueries in SELECTSubqueries in FROMSubqueries in WHERE

SQL Views

Creating SQL ViewsAltering SQL ViewsDropping SQL ViewsUpdatable ViewsMaterialized ViewsView Limitations

SQL Transactions

SQL Transaction BasicsACID PropertiesBEGIN TRANSACTIONCOMMITROLLBACKSAVEPOINTTransaction Isolation Levels

SQL Data Definition

SQL CREATE TABLESQL ALTER TABLESQL DROP TABLESQL TRUNCATE TABLESQL CREATE INDEXSQL DROP INDEXSQL CREATE DATABASESQL ALTER DATABASESQL DROP DATABASE

SQL Data Control

SQL GRANTSQL REVOKESQL RolesSQL UsersSQL Privileges

SQL Performance Optimization

SQL Query OptimizationSQL Execution PlansSQL Index OptimizationSQL Query TuningSQL CachingSQL Partitioning

Advanced SQL Concepts

SQL Stored ProceduresSQL TriggersSQL CursorsSQL Common Table ExpressionsSQL Window FunctionsSQL Pivot and UnpivotSQL JSON OperationsSQL XML OperationsSQL Full-Text Search

SQL Best Practices

SQL Naming ConventionsSQL Code OrganizationSQL Error HandlingSQL Security Best PracticesSQL Backup and RecoverySQL Version Control

SQL Identifiers: Naming Database Objects

SQL identifiers are names used to identify various database objects such as tables, columns, views, and indexes. They play a crucial role in SQL Database Management Systems, allowing developers and users to reference specific elements within a database.

Understanding SQL Identifiers

In SQL, identifiers serve as unique labels for database objects. They are essential for creating, modifying, and querying data structures. Proper use of identifiers ensures clarity and prevents naming conflicts in your database schema.

Basic Rules for SQL Identifiers

  • Must begin with a letter (a-z, A-Z) or underscore (_)
  • Can contain letters, numbers, and underscores
  • Cannot exceed 128 characters in most database systems
  • Should not be SQL Keywords
  • Case-sensitivity varies depending on the database system and configuration

Examples of SQL Identifiers

Here are some valid SQL identifier examples:


CREATE TABLE employees (
    employee_id INT PRIMARY KEY,
    first_name VARCHAR(50),
    last_name VARCHAR(50),
    hire_date DATE
);

CREATE VIEW senior_employees AS
SELECT * FROM employees
WHERE hire_date < '2010-01-01';

In this example, "employees", "employee_id", "first_name", "last_name", "hire_date", and "senior_employees" are all SQL identifiers.

Quoted Identifiers

Some database systems allow the use of quoted identifiers, which provide more flexibility in naming:


CREATE TABLE "My Table" (
    "Column 1" INT,
    "2nd Column" VARCHAR(50)
);

Quoted identifiers can include spaces and special characters, but they may require extra attention when querying.

Best Practices for SQL Identifiers

  1. Use descriptive names that reflect the purpose of the object
  2. Maintain consistency in naming conventions across your database
  3. Avoid using reserved SQL Keywords as identifiers
  4. Consider using prefixes or suffixes to group related objects
  5. Use underscores for multi-word identifiers (e.g., "order_details" instead of "orderdetails")

Case Sensitivity in SQL Identifiers

SQL Case Sensitivity varies among different database management systems:

  • MySQL: Case-insensitive by default on Windows, case-sensitive on Unix-based systems
  • PostgreSQL: Case-sensitive, but converts unquoted identifiers to lowercase
  • Oracle: Case-insensitive by default, but stores identifiers in uppercase
  • SQL Server: Case-insensitive by default, but can be configured for case sensitivity

It's crucial to understand the case sensitivity rules of your specific database system to avoid potential issues.

Conclusion

SQL identifiers are fundamental to database design and management. By following best practices and understanding the rules governing identifiers, you can create clear, maintainable, and efficient database structures. Remember to consult your specific database system's documentation for any system-specific guidelines or limitations regarding identifiers.