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Functions in SQL

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Functions in SQL

SQL functions are built-in operations that perform calculations, transformations, and data processing tasks on database values.

📝Syntax
SELECT function_name(column)
FROM table_name;
functions-in-sql.sql
📝 Edit Code
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💡 This preview does not execute SQL; it’s for reading/editing the query.
💡What are SQL Functions?
  • 1Predefined operations in SQL.
  • 2Perform calculations and transformations.
  • 3Used in SELECT queries.
  • 4Simplify data handling.
💡Types of SQL Functions
  • 1String Functions (UPPER, LOWER).
  • 2Numeric Functions (ABS, ROUND).
  • 3Date Functions (NOW, CURDATE).
  • 4Aggregate Functions (COUNT, SUM).
💡String Functions
  • 1Used to manipulate text data.
  • 2Example: UPPER(name).
  • 3LOWER() converts to lowercase.
  • 4Useful in formatting output.
💡Numeric Functions
  • 1Used for mathematical operations.
  • 2ABS() returns absolute value.
  • 3ROUND() rounds numbers.
  • 4Useful in calculations.
💡Date Functions
  • 1Work with date and time values.
  • 2NOW() returns current timestamp.
  • 3CURDATE() returns current date.
  • 4Used in scheduling systems.
💡Aggregate Functions
  • 1Perform calculations on multiple rows.
  • 2COUNT(), SUM(), AVG().
  • 3Used in reporting.
  • 4Return single result.
🏢Real-world
  • 1Formatting names in reports.
  • 2Calculating totals and averages.
  • 3Processing date and time values.
  • 4Generating summary reports.
  • 5Data transformation in queries.
⚠Common Mistakes
  • 1Using wrong function type.
  • 2Applying functions on large datasets unnecessarily.
  • 3Ignoring performance impact.
  • 4Using functions in WHERE clause incorrectly.
✅Best Practices
  • 1Use appropriate function for task.
  • 2Avoid unnecessary function usage.
  • 3Be careful using functions in indexed columns.
  • 4Combine functions with optimized queries.
✅Quick Summary
  • SQL functions process and transform data.
  • Include string, numeric, date, and aggregate functions.
  • Used in SELECT queries.
  • Simplify data manipulation.
  • Improve query efficiency.
🎯Interview Questions
Q1. What are SQL functions?
Answer: Built-in operations to process and manipulate data.
Q2. What are types of SQL functions?
Answer: String, numeric, date, and aggregate functions.
Q3. What does UPPER() function do?
Answer: Converts text to uppercase.
Q4. What is COUNT() used for?
Answer: It counts the number of rows.
Q5. Where are SQL functions used?
Answer: In SELECT queries for data processing.
❓Quiz

Which function is used to count rows in SQL?

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Stored ProceduresCreating Stored ProceduresCalling Stored ProceduresUser-Defined FunctionsTriggers in SQLBEFORE TriggerWhat is SQL?History of SQLFeatures of SQLWhy Learn SQL?
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