TABLES AND SQL

Controlling Tables Programmatically

By: Amit Kumar Singh

Tables

• 2 Dimensional matrix• Unique name

SQL

• Structured Query Language • ANSI standard computer language

• Allows you to access a database

• Execute queries, retrieve, insert, delete, update records

• Freedom from intricacy & details of database softwares.

• EASY TO LEARN

Creating Tables

• CREATE TABLE table_name

( column_name1 data_type, column_name2 data_type, ....... ) ;

Example, • CREATE TABLE Person  (

LastName varchar(30), FirstName varchar, Address varchar, Age int(3)  ) ;

• Create Table tbldemo

( Name text(30),

Age integer,

Gender text(1)

);• Data type depends on the Database management software you are using

SQL ALTER TABLE

• ALTER TABLE table_name ADD COLUMN_name datatype

• ALTER TABLE table_name DROP COLUMN column_name

• Example,

• ALTER TABLE tbldemo ADD COLUMN date_of_birth datetime

• ALTER TABLE tbldemo DROP COLUMN marks;

SQL INSERT

• INSERT INTO table_name VALUES (value1, value2,....)

• INSERT INTO table_name (column_name1,column_name2,...)VALUES(value1, value2,....)

• Example,

• INSERT INTO tbldemo VALUES ('Amit', 22, 'm', #8/22/1982#, 27474017);

• INSERT INTO tbldemo ( Name, Age, Gender, date_of_birth )

VALUES ('Preeti', 22, 'f', #2/18/1982#);

SQL SELECT

• SELECT column_name(s) FROM table_name

• SELECT * FROM table_name

• SELECT * INTO new_table_name FROM original_table_name

• SELECT column_name(s) FROM table_name WHERE condition

• Example,

• SELECT Name FROM tbldemo WHERE GENDER='f';

SQL UPDATE

• UPDATE table_nameSET column_name=new_value[, column_name=new_value]WHERE column_name=some_value ;

• Example,

• UPDATE tbldemo SET phone_no = 22523250 WHERE name='ShriRam';

SQL DELETE

• DELETE FROM table_name WHERE condition

• DELETE FROM table_name (Note: Deletes the entire table!!)

• Example,• DELETE FROM tbldemo WHERE Gender='f';

SQL DROP TABLE

• DROP TABLE table_name

• Example,

• DROP TABLE tbldemo;

More SQL…

• http://www.w3schools.com/sql/default.asp

• http://w3.one.net/~jhoffman/sqltut.htm