navigate创建表，查询表

Question

不会创建，和查询，修改，删除都不会
create database
select

Answer 1

创建数据库

CREATE DATABASE databasename;

创建表

CREATE TABLE tablename (
   column1 datatype,
   column2 datatype,
   column3 datatype,
   .....
);

插入数据

向表中插入数据

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

查询数据

查询表中所有数据

SELECT * FROM tablename;

指定要查询的列

SELECT column1, column2, .... FROM tablename;

使用 WHERE 语句进行筛选

SELECT * FROM tablename WHERE column1 = some_value;

排序

SELECT * FROM tablename ORDER BY column1 ASC/DESC;

分组运算

SELECT column1, COUNT(column2), AVG(column3) FROM tablename GROUP BY column1;

更新数据

更新表中数据

UPDATE tablename SET column1 = value1, column2 = value2, .... WHERE some_column = some_value;

删除数据

删除表中数据

DELETE FROM tablename WHERE some_column = some_value;

删除表

DROP TABLE tablename;

删除数据库

DROP DATABASE databasename;