SQL cheat sheet (123 dòng):
----- Basic Commands - Nhóm lệnh cơ bản -----
-- Select data from a table
SELECT column1, column2
FROM table_name;
-- Select all columns
SELECT * FROM table_name;
-- Insert data into a table
INSERT INTO table_name (column1, column2)
VALUES (value1, value2);
-- Update data in a table
UPDATE table_name
SET column1 = value1, column2 = value2
WHERE condition;
-- Delete data from a table
DELETE FROM table_name
WHERE condition;
----- Filtering Data - Lọc -----
-- Where clause
SELECT column1, column2
FROM table_name
WHERE condition;
-- Logical operators
SELECT column1, column2
FROM table_name
WHERE condition1 AND condition2;
WHERE condition1 OR condition2;
-- Pattern matching
SELECT column1, column2
FROM table_name
WHERE column1 LIKE 'pattern%';
----- Aggregating Data - Tổng hợp -----
-- Count
SELECT COUNT(column_name)
FROM table_name;
-- Sum
SELECT SUM(column_name)
FROM table_name;
-- Average
SELECT AVG(column_name)
FROM table_name;
-- Min and Max
SELECT MIN(column_name)
FROM table_name;
SELECT MAX(column_name)
FROM table_name;
----- Grouping and Sorting - Nhóm vs Sắp xếp -----
-- Group By
SELECT column1, COUNT(*)
FROM table_name
GROUP BY column1;
-- Having (with Group By)
SELECT column1, COUNT(*)
FROM table_name
GROUP BY column1
HAVING COUNT(*) > 1;
-- Order By
SELECT column1, column2
FROM table_name
ORDER BY column1 ASC;
ORDER BY column1 DESC;
----- Joining Tables - Nối bảng -----
-- Inner Join
SELECT a.column1, b.column2
FROM table1 a
INNER JOIN table2 b ON a.common_column = b.common_column;
-- Left Join
SELECT a.column1, b.column2
FROM table1 a
LEFT JOIN table2 b ON a.common_column = b.common_column;
-- Right Join
SELECT a.column1, b.column2
FROM table1 a
RIGHT JOIN table2 b ON a.common_column = b.common_column;
-- Full Outer Join
SELECT a.column1, b.column2
FROM table1 a
FULL OUTER JOIN table2 b ON a.common_column = b.common_column;
-----Miscellaneous - Lặt vặt-----
-- Create Table
CREATE TABLE table_name (
column1 datatype PRIMARY KEY,
column2 datatype,
column3 datatype
);
-- Drop Table
DROP TABLE table_name;
-- Alter Table
ALTER TABLE table_name
ADD column_name datatype;
ALTER TABLE table_name
DROP COLUMN column_name;