1. Data Query Language (DQL)

• SELECT
  SELECT column1, column2, ... FROM table_name WHERE condition GROUP BY column1, column2, ... HAVING condition ORDER BY column1, column2

2. Data Definition Language (DDL)

• CREATE TABLE
  CREATE TABLE table_name ( column1 datatype constraints, column2 datatype constraints, ... );
• ALTER TABLE
  • Add Column
    ALTER TABLE table_name ADD column_name datatype constraints;
  • Drop Column
    ALTER TABLE table_name DROP COLUMN column_name;
  • Modify Column
    ALTER TABLE table_name MODIFY COLUMN column_name datatype constraints;
• DROP TABLE
  DROP TABLE table_name;
• CREATE INDEX
  CREATE INDEX index_name ON table_name (column1, column2, ...);
• DROP INDEX
  DROP INDEX index_name;

3. Data Manipulation Language (DML)

• INSERT INTO
  INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...);
• UPDATE
  UPDATE table_name SET column1 = value1, column2 = value2, ... WHERE condition;
• DELETE
  DELETE FROM table_name WHERE condition;

4. Data Control Language (DCL)

• GRANT
  GRANT privilege_type ON object_name TO user_name;
• REVOKE
  REVOKE privilege_type ON object_name FROM user_name;

5. Transaction Control Language (TCL)

• COMMIT
  COMMIT;
• ROLLBACK
  ROLLBACK;
• SAVEPOINT
  SAVEPOINT savepoint_name;
• SET TRANSACTION
  SET TRANSACTION ISOLATION LEVEL level;

6. Join Operations

• INNER JOIN
  SELECT columns FROM table1 INNER JOIN table2 ON table1.column = table2.column;
• LEFT JOIN (LEFT OUTER JOIN)
  SELECT columns FROM table1 LEFT JOIN table2 ON table1.column = table2.column;
• RIGHT JOIN (RIGHT OUTER JOIN)
  SELECT columns FROM table1 RIGHT JOIN table2 ON table1.column = table2.column;
• FULL JOIN (FULL OUTER JOIN)
  SELECT columns FROM table1 FULL JOIN table2 ON table1.column = table2.column;

7. Subqueries

• Basic Subquery
  SELECT column1 FROM table_name WHERE column2 = (SELECT column2 FROM another_table WHERE condition);
• Correlated Subquery
  SELECT column1 FROM table1 t1 WHERE EXISTS (SELECT 1 FROM table2 t2 WHERE t1.column = t2.column);

8. Set Operations

• UNION
  SELECT column1, column2 FROM table1 UNION SELECT column1, column2 FROM table2;
• INTERSECT
  SELECT column1, column2 FROM table1 INTERSECT SELECT column1, column2 FROM table2;
• EXCEPT (or MINUS in some SQL dialects)
  SELECT column1, column2 FROM table1 EXCEPT SELECT column1, column2 FROM table2;

9. Aggregate Functions

• COUNT
  SELECT COUNT(column_name) FROM table_name;
• SUM
  SELECT SUM(column_name) FROM table_name;
• AVG
  SELECT AVG(column_name) FROM table_name;
• MAX
  SELECT MAX(column_name) FROM table_name;
• MIN
  SELECT MIN(column_name) FROM table_name;

10. Conditional Expressions

• CASE
  SELECT column1, CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ELSE result_default END AS alias_name FROM table_name;

11. String Functions

• CONCAT
  SELECT CONCAT(column1, column2) AS concatenated_column FROM table_name;
• SUBSTRING
  SELECT SUBSTRING(column_name FROM start_position FOR length) AS sub_column FROM table_name;
• LENGTH
  SELECT LENGTH(column_name) AS length FROM table_name;

12. Date and Time Functions

• NOW
  SELECT NOW() AS current_datetime;
• DATEADD
  SELECT DATEADD(day, number_of_days, date_column) AS new_date FROM table_name;
• DATEDIFF
  SELECT DATEDIFF(day, start_date, end_date) AS days_diff FROM table_name;

13. Data Types

• Numeric Types: INT, FLOAT, DECIMAL, etc.
• Character Types: VARCHAR, CHAR, TEXT, etc.
• Date and Time Types: DATE, TIME, DATETIME, TIMESTAMP, etc.

14. Constraints

• PRIMARY KEY
  column_name datatype PRIMARY KEY
• FOREIGN KEY
  FOREIGN KEY (column_name) REFERENCES other_table(column_name)
• UNIQUE
  column_name datatype UNIQUE
• NOT NULL
  column_name datatype NOT NULL
• DEFAULT
  column_name datatype DEFAULT default_value

This list should give you a solid overview of SQL syntax and operations.