SQL常用语法及示例汇总

SQL（Structured Query Language）是用于管理和操作数据库的标准编程语言，是数据存储、查询、更新和管理的核心工具。以下是SQL的9种基础语法： 1. SELECT语句：基本查询语句，用于从数据库中选取数据。示例：SELECT * FROM table_name; 2. FROM子句：指定要查询的表。示例：SELECT column_name FROM table_name; 3. WHERE子句：过滤满足特定条件的记录。示例：SELECT column_name FROM table_name WHERE condition; 4. ORDER BY子句：对结果集进行排序。示例：SELECT column_name FROM table_name ORDER BY column_name ASC/DESC; 5. GROUP BY子句：对数据进行分组。示例：SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name; 6. HAVING子句：过滤GROUP BY后的结果。示例：SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name HAVING COUNT(*) > some_value; 7. JOIN操作：合并两个或更多表的数据。示例：SELECT * FROM table1 JOIN table2 ON table1.id = table2.id; 8. INSERT语句：向表中插入新记录。示例：INSERT INTO table_name (column1, column2) VALUES (value1, value2); 9. UPDATE语句：更新现有记录。示例：UPDATE table_name SET column1 = value1 WHERE condition;