MySQL是一種開源的數據庫管理系統，它的查詢命令可用于從數據庫中提取數據。以下是MySQL查詢常用的基本命令：

SELECT：從表中選擇一些特定的列或者所有的列。
語法：SELECT column1, column2, ...... FROM table_name;
示例：SELECT * FROM customers;
SELECT CustomerID, CustomerName FROM customers;
FROM：用于指定要查詢的表名稱。
語法：SELECT column1, column2, ...... FROM table_name;
示例：SELECT * FROM customers;
WHERE：從指定的表中選取符合條件的行。
語法：SELECT column1, column2, ...... FROM table_name WHERE condition;
示例：SELECT * FROM customers WHERE Country='Germany';
ORDER BY：按照指定列對結果集進行排序。
語法：SELECT column1, column2, ...... FROM table_name ORDER BY column_name ASC|DESC;
示例：SELECT * FROM customers ORDER BY Country ASC;
SELECT * FROM customers ORDER BY Country DESC;
GROUP BY：對查詢結果按照指定列進行分組。
語法：SELECT column1, column2, ...... FROM table_name GROUP BY column_name;
示例：SELECT COUNT(CustomerID), Country FROM customers GROUP BY Country;
HAVING：結合GROUP BY一起使用，過濾分組后的數據。
語法：SELECT column1, column2, ...... FROM table_name GROUP BY column_name HAVING condition;
示例：SELECT COUNT(CustomerID), Country FROM customers GROUP BY Country HAVING COUNT(CustomerID) >5;

以上是MySQL查詢的基本命令，它們可以混合使用，以滿足不同場景的需求。