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Topics

Introduction to SQL

What is SQL?SQL History SQL Standards SQL vs NoSQL SQL Database Management Systems

SQL Basics

SQL Syntax SQL Comments SQL Data Types SQL Operators SQL Expressions SQL Literals SQL Identifiers SQL Keywords SQL Case Sensitivity

SQL Database Fundamentals

Database Concepts Tables and Fields Primary Keys Foreign Keys Indexes Constraints Normalization Denormalization SQL Schema Design

SQL Data Manipulation

SQL SELECT Statement SQL INSERT Statement SQL UPDATE Statement SQL DELETE Statement SQL MERGE Statement SQL Aliases SQL Wildcards SQL LIKE Operator SQL IN Operator SQL BETWEEN Operator SQL NULL Values SQL ORDER BY Clause SQL LIMIT Clause SQL OFFSET Clause

SQL Filtering and Sorting

SQL WHERE Clause SQL AND, OR, NOT Operators SQL GROUP BY Clause SQL HAVING Clause SQL DISTINCT Keyword SQL TOP Clause

SQL Joins

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

SQL Functions

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

SQL Subqueries

SQL Subquery Basics Correlated Subqueries Nested Subqueries SQL EXISTS Operator SQL ANY and ALL Operators Subqueries in SELECT Subqueries in FROM Subqueries in WHERE

SQL Views

Creating SQL Views Altering SQL Views Dropping SQL Views Updatable Views Materialized Views View Limitations

SQL Transactions

SQL Transaction Basics ACID Properties BEGIN TRANSACTION COMMIT ROLLBACK SAVEPOINT Transaction Isolation Levels

SQL Data Definition

SQL CREATE TABLE SQL ALTER TABLE SQL DROP TABLE SQL TRUNCATE TABLE SQL CREATE INDEX SQL DROP INDEX SQL CREATE DATABASE SQL ALTER DATABASE SQL DROP DATABASE

SQL Data Control

SQL GRANT SQL REVOKE SQL Roles SQL Users SQL Privileges

SQL Performance Optimization

SQL Query Optimization SQL Execution Plans SQL Index Optimization SQL Query Tuning SQL Caching SQL Partitioning

Advanced SQL Concepts

SQL Stored Procedures SQL Triggers SQL Cursors SQL Common Table Expressions SQL Window Functions SQL Pivot and Unpivot SQL JSON Operations SQL XML Operations SQL Full-Text Search

SQL Best Practices

SQL Naming Conventions SQL Code Organization SQL Error Handling SQL Security Best Practices SQL Backup and Recovery SQL Version Control

SQL Conversion Functions

SQL conversion functions are essential tools in database management, allowing you to transform data from one type to another. These functions play a crucial role in data manipulation and reporting.

Purpose of Conversion Functions

Conversion functions serve several important purposes:

Data type compatibility: Ensure proper comparisons and operations between different data types
Formatting: Present data in a specific format for display or analysis
Data cleaning: Convert inconsistent data into a standardized format

Common SQL Conversion Functions

1. CAST

The CAST function converts a value from one data type to another.

SELECT CAST(column_name AS data_type) FROM table_name;

2. CONVERT

Similar to CAST, CONVERT changes data types but offers additional style options for certain conversions.

SELECT CONVERT(data_type[(length)], expression [, style]) FROM table_name;

3. TO_CHAR

Converts numbers or dates to a string format.

SELECT TO_CHAR(date_column, 'YYYY-MM-DD') FROM table_name;

4. TO_DATE

Converts a string to a date format.

SELECT TO_DATE('2023-05-15', 'YYYY-MM-DD') FROM dual;

Practical Examples

Example 1: Converting Numeric to String

SELECT CAST(price AS VARCHAR(10)) AS price_string
FROM products;

Example 2: Date Formatting

SELECT TO_CHAR(order_date, 'Month DD, YYYY') AS formatted_date
FROM orders;

Best Practices

Always validate input data before conversion to avoid errors
Use appropriate data types to optimize storage and performance
Consider using SQL Indexes on frequently converted columns for better query performance
Be aware of potential data loss when converting to a less precise data type

Related Concepts

To further enhance your understanding of SQL data manipulation, explore these related topics:

Mastering SQL conversion functions is crucial for effective data management and analysis. By understanding these functions, you can ensure data consistency and improve the overall quality of your database operations.