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SQL Dictionary

SQL Dictionary

Beginners Guide: Overview, Features, and Learning Path	An overview of SQL, features and trade-offs, key feature explanations, and a recommended learning order for this dictionary.
[Setup] SQL Execution Environment	Steps for setting up an environment to execute SQL.
Creating and Running .sql Files	How to write .sql files and execute them in each database.
SELECT	Basic syntax for retrieving rows and columns.
WHERE	Filtering rows by condition.
AND / OR / NOT	Logical operators for combining multiple conditions.
LIKE	Pattern-matching search.
IS NULL / IS NOT NULL	Checking for NULL values.
ORDER BY	Sorting query results.
LIMIT / OFFSET	Specifying the number of rows to retrieve and the starting position.
INSERT	Inserting rows into a table.
UPDATE	Updating existing rows.
DELETE	Deleting rows from a table.
TRUNCATE	Quickly deleting all rows from a table.
COUNT	Counting the number of rows or records.
SUM / AVG	Calculating sums and averages.
MAX / MIN	Finding maximum and minimum values.
GROUP BY / HAVING	Grouping data and filtering aggregated results.
INNER JOIN	Joining rows that match in both tables.
LEFT JOIN / RIGHT JOIN	Joining while keeping all rows from one table.
FULL OUTER JOIN	Joining while keeping all rows from both tables.
CROSS JOIN	A Cartesian product join that generates all combinations.
SELF JOIN	Joining a table with itself.
Subqueries (Scalar and Row)	Subqueries that return a single value or row.
IN / EXISTS	Checking for matches against subquery results.
ALL / ANY	Comparing against all or any values returned by a subquery.
Correlated Subqueries	Subqueries that reference the outer query.
UNION / UNION ALL	Vertically combining results from multiple SELECT statements.
INTERSECT / EXCEPT	Extracting common rows or the difference between result sets.
OVER / PARTITION BY	Basic syntax for window functions.
ROW_NUMBER / RANK / DENSE_RANK	Assigning ranks and sequential numbers to rows.
LAG / LEAD	Referencing values from preceding or following rows.
SUM / AVG (Window)	Calculating running totals and moving averages.
CONCAT / LENGTH	Concatenating strings and getting their length.
SUBSTRING / TRIM	Extracting substrings and trimming leading/trailing whitespace.
UPPER / LOWER / REPLACE	Converting case and replacing strings.
LIKE (Function) / POSITION	Searching for character positions and checking pattern matches.
ROUND / CEIL / FLOOR	Rounding numeric values.
ABS / MOD / POWER	Absolute values, modulo, and exponentiation.
CURRENT_DATE / NOW	Getting the current date and time.
DATE_ADD / DATEDIFF	Adding/subtracting dates and calculating date differences.
EXTRACT / FORMAT	Extracting year, month, day, etc. from a date and formatting it.
CASE	Switching values based on conditional logic.
COALESCE / NULLIF	Replacing NULL with another value.
CAST / CONVERT	Converting data types.
CREATE TABLE	Creating a table.
Constraints (NOT NULL / UNIQUE / DEFAULT)	Basic column-level constraints.
PRIMARY KEY / FOREIGN KEY	Primary key and foreign key constraints.
ALTER TABLE	Modifies the definition of an existing table.
CREATE INDEX	Creates or drops an index on a table.
VIEW	Creates, updates, or drops a view.
WITH (CTE)	Improves query readability using Common Table Expressions.
TRANSACTION / COMMIT / ROLLBACK	Begins, commits, or rolls back a transaction.
GRANT / REVOKE	Grants or revokes privileges for a user.
EXPLAIN	Displays the execution plan of a query.
AUTO_INCREMENT / SERIAL / IDENTITY	A feature that automatically assigns sequential numbers to a primary key column; MySQL uses AUTO_INCREMENT, PostgreSQL uses SERIAL, SQL Server uses IDENTITY.
BETWEEN ... AND ...	An operator that specifies an inclusive range condition; usable with numbers, dates, and strings.
Comments -- / # / /* */	Three comment types: single-line (--), MySQL-only single-line (#), and block comments (/* */).
Data Types	An overview of major SQL data types including numeric, string, date, and boolean types, with notes on differences across DBMSes.
GROUP_CONCAT / STRING_AGG	Aggregate functions that concatenate multiple row values within a group into a single string; MySQL uses GROUP_CONCAT, PostgreSQL and SQL Server use STRING_AGG.
IF() / IIF() Functions	Shortcut functions that return different values based on a condition; MySQL uses IF(), SQL Server uses IIF().
INSERT INTO ... SELECT	Syntax for bulk-inserting the results of a SELECT statement into another table, used for copying data between tables or filtered extraction.

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