Hidden SQL Facts
Here are 50 things you might not know about SQL:
- SQL stands for Structured Query Language.
- It was first developed by IBM in the 1970s.
- SQL is not case-sensitive for keywords but is case-sensitive for data.
- SQL operates on relational databases, which store data in tables.
- There are different SQL database management systems (DBMS) like MySQL, PostgreSQL, SQLite, and Oracle.
- SQL can be used for data manipulation (INSERT, UPDATE, DELETE) and querying (SELECT).
- The SQL SELECT statement is used to retrieve data from a database.
- SQL supports various types of joins: INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.
- GROUP BY is used to aggregate data and apply functions like SUM, COUNT, AVG, etc.
- HAVING filters results after the GROUP BY clause.
- SQL's ORDER BY sorts query results in ascending or descending order.
- SQL supports subqueries, allowing you to nest one query within another.
- The UNION operator combines results from multiple SELECT statements.
- SQL views are virtual tables that store the result of a SELECT query.
- Transactions ensure data consistency and can be managed using BEGIN, COMMIT, and ROLLBACK.
- ACID (Atomicity, Consistency, Isolation, Durability) properties ensure data integrity.
- SQL injection is a security vulnerability that occurs when user input is not properly sanitized.
- Common data types in SQL include INTEGER, VARCHAR, DATE, and BOOLEAN.
- The ALTER TABLE statement is used to modify existing database tables.
- INDEXES improve query performance by providing faster data retrieval.
- Stored procedures are precompiled SQL code for specific tasks.
- Triggers are automatic actions that respond to certain events in the database.
- SQL supports regular expressions for advanced pattern matching.
- The CASE statement performs conditional logic in SQL queries.
- SQL supports scalar functions (UPPER, LOWER) and mathematical functions (ABS, ROUND).
- Common aggregate functions include MAX, MIN, SUM, AVG, and COUNT.
- The PRIMARY KEY uniquely identifies a row in a table.
- FOREIGN KEY establishes relationships between tables.
- SQL NULL represents the absence of a value.
- The COALESCE function returns the first non-null value in a list.
- Full-text search allows searching for text within a large body of text data.
- SQL's MERGE statement combines INSERT, UPDATE, and DELETE operations.
- Window functions perform calculations across a set of table rows.
- Common window functions are ROW_NUMBER, RANK, DENSE_RANK, and LAG.
- The OFFSET-FETCH clause is used for result pagination.
- Common table expressions (CTEs) simplify complex queries by creating temporary result sets.
- JSON functions allow storing, querying, and manipulating JSON data.
- Temporal tables store historical data, allowing you to track changes over time.
- SQL Workbench is a popular open-source SQL client tool.
- SQL Server Management Studio (SSMS) is a Microsoft tool for SQL Server.
- pgAdmin is a widely used open-source administration and management tool for PostgreSQL.
- SQL transactions can be managed using the COMMIT and ROLLBACK statements.
- The EXISTS operator checks for the existence of rows in a subquery.
- The ROW_NUMBER() function assigns a unique number to each row in a result set.
- Common table expressions (CTEs) improve query readability and reusability.
- The LIKE operator and wildcard characters allow pattern matching in queries.
- SQL's TRUNCATE statement removes all rows from a table without logging individual deletions.
- The CASE statement can perform conditional updates and inserts.
- The COALESCE function is used to return the first non-null value in a list of expressions.
- SQL is used not only in databases but also in data warehousing and data analytics platforms.
- Feel free to ask if you'd like more details on any of these points!