SQL Basic Syntax

SQL DML and DDL can divide SQL into two parts: Data manipulation Language (DML) and data definition language (DDL).

SQL (Structured Query language) is the syntax for executing queries. However, the SQL language also contains syntax for updating, inserting, and deleting records.

The query and update Directives form the DML portion of SQL:

• SELECT -get data from a database table
• Update-updating data in a database table
• Delete-deletes data from the database table
• INSERT INTO-inserts data into a database table

The Data definition language (DDL) portion of SQL gives us the ability to create or delete tables. We can also define indexes (keys), specify links between tables, and impose constraints between tables.

The most important DDL statement in SQL:

• CREATE database-creating new databases
• alter database-Modify Databases
• CREATE TABLE-Creates a new table
• ALTER TABLE -Change (change) database table
• Drop Table-delete tables
• CREATE index-Creating indexes (search key)
• Drop Index-delete indexes

Example (Mysql):

We have a personnel database with such a data sheet:

City

Id	LastName	FirstName	Address
1	Adams	John	Oxford Street	London
2	Bush	George	Fifth Avenue	New York
3	Carter	Thomas	Changan Street	Beijing

First create the database:

Create Database w3s;

To view the database that was created:

show databases;

Select the database you want to use:

Use DatabaseName;

Create a table:

CREATE TABLE TableName (------------------------------------------------)

To view the structure of a table:

DESC TableName;

To insert data into a table:

INSERT INTO tablename VALUES (--------) inserts all properties

INSERT INTO TableName (P1,P2,P3--) VALUES (n1, N2,N3--); order to correspond

Get the data from the table:

Select P1,p2,p3---PN from TableName;

Get all the data in the table by using the wildcard character *

Reference:

Http://www.w3school.com.cn/sql/sql_syntax.asp

Http://www.runoob.com/sql/sql-syntax.html

SQL Basic Syntax