orcel常用语句教程

Oracle 常用 SQL 语句教程：

1. 创建表：

CREATE TABLE table_name (
   column1 datatype [ NULL | NOT NULL ],
   column2 datatype [ NULL | NOT NULL ],
   ...
   columnN datatype [ NULL | NOT NULL ]
);

2. 修改表：

ALTER TABLE table_name
   ADD column_name datatype;

ALTER TABLE table_name
   MODIFY column_name datatype;

ALTER TABLE table_name
   DROP COLUMN column_name;

3. 插入数据：

INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...);

4. 更新数据：

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

5. 删除数据：

DELETE FROM table_name WHERE condition;

6. 查询数据：

SELECT column1, column2, ... FROM table_name WHERE condition;

7. 排序：

SELECT column1, column2, ...
FROM table_name
ORDER BY column1 [ASC | DESC], column2 [ASC | DESC], ...;

8. 分组：

SELECT column1, COUNT(column2)
FROM table_name
GROUP BY column1;

9. 连接：

SELECT column1, column2, ...
FROM table1
JOIN table2
ON table1.column_name = table2.column_name;

10. 子查询：

SELECT column1, column2, ...
FROM table_name
WHERE column_name IN (SELECT column_name FROM table_name2 WHERE condition);