- SELECT - 从数据库中提取数据
SELECT column_name,column_name
FROM table_name;
SELECT DISTINCT column_name,column_name
FROM table_name;
DISTINCT 关键词用于返回唯一不同的值。
- UPDATE - 更新数据库中的数据
UPDATE table_name
SET column1=value1,column2=value2,...
WHERE some_column=some_value;
- DELETE - 从数据库中删除数据
DELETE FROM table_name
WHERE some_column=some_value;
- INSERT INTO - 向数据库中插入新数据
INSERT INTO table_name (column1,column2,column3,...)
VALUES (value1,value2,value3,...);
INSERT INTO table_name
VALUES (value1,value2,value3,...);
- CREATE DATABASE - 创建新数据库
CREATE DATABASE my_db;
- CREATE TABLE - 创建新表
CREATE TABLE table_name
(
column_name1 data_type(size),
column_name2 data_type(size),
column_name3 data_type(size),
....
);
- ALTER TABLE - 变更(改变)数据库表
ALTER TABLE table_name
ADD column_name datatype
ALTER TABLE table_name
DROP COLUMN column_name
- DROP TABLE - 删除表
DROP TABLE table_name
- CREATE INDEX - 创建索引(搜索键)
CREATE INDEX index_name
ON table_name (column_name)
- DROP INDEX - 删除索引
ALTER TABLE table_name DROP INDEX index_name