SQL

pepper

Why SQL

• File I/O is a great deal of code• Optimal file organization and indexing is

critical and a great deal of code and theory implementation

• File locking• Security concerns• Much more

Different SQL Servers

• Mysql (open source – no cost to use though may cost to embed and resell outside gpl)

• Ms sql (microsoft )• Oracle• Sybase• Access• Older AS/400 – SQL machine

Structure

• SQL Server runs a service • accepts sql commands using their version of

the standard query language• Allows access to the data inside the SQL server• Organized into databases• Tables (like spreadsheets) inside databases• Gui management interface – Access / mysql workbench / mssql studio mgr

Your databases• Connect with : mysql -u yourdbuser -p yourdatabase– The –p means the password will be entered later. You can

also put the password right after the p as in pmypassword. No spaces and no quotes

– Your database name is your db user and is usually your ecampus logon name

– You should also be able to connect to pepperdb• See your tables

show tables• See information inside your table select * from tablename

Create a table• CREATE TABLE table_name (column_name column_type );• Plus insert PRIMARY KEY ( id ) at end• Ex: • create table tut(

id INT NOT NULL AUTO_INCREMENT,title VARCHAR(100) NOT NULL,type VARCHAR(40) NOT NULL,date DATE, PRIMARY KEY ( id ) );

Credit to : http://www.tutorialspoint.com/mysql/mysql-create-tables.htm

Create a related table

• Create table types ( type VARCHAR(40) NOT NULL, name VARCHAR(100) NOT NULL, manager int not null,PRIMARY KEY ( type) );

Table picture from wikipedia

Insert a row• INSERT INTO table_name ( field1, field2,...fieldN )

VALUES ( value1, value2,...valueN );• Examples:• INSERT INTO tut ( title, type, submission_date)

VALUES ("Learn PHP", "php",NOW());• INSERT INTO tut (title, type, submission_date)

VALUES ("Learn MySQL", "db",NOW());• INSERT INTO tut (title, type, submission_date)

VALUES ("Learn Oracle", "db",NOW());

Credit: http://www.tutorialspoint.com/mysql/mysql-insert-query.htm

Insert rows into another table

• INSERT INTO types values ("php", "php tutorials",10);

• INSERT INTO types values ("db", "database tutorials",20);

Query your tables

• select * from tut ;• select * from types;• select * from types inner join tut on

tut.type = types.type;

Select statement

• Select – keyword indicating just looking• List all columns (* for all; table.column)• From – keyword indicating table names follow• Table name• Join type + next table + on + matching fields• Where – keyword indicating row selection• Column = something

Switch to another database

• Show databases• Use <database name>

MySQL Workbench

• Mysql IDE• Free community version– Install with connector/J so you can connect to java– Your server password is critical

• Models vs Database vs Server Instance– Model forward engineer to database– Forward engineer script can be run on panther

Java and Sql• Need a connection driver– Mysql : connecter /j -> jdbc– Java: – Add mysql connector/j jar file to your IDE– Your code: • Import java.sql.*• Load the jdbc driver inside your code

– Class.forName("com.mysql.jdbc.Driver").newInstance();

• Create a connection object– Connection conn =

DriverManager.getConnection("jdbc:mysql://localhost:3306","root","root");

Java and SQL cont

• Make an sql statement object– Statement st = conn.createStatement();

• Build a statement– String aSQLst = "create database warehouse"

• Execute the statement– st.execute(aSQLst);

Java and SQL get results• Select statement will return a result as a result set

object• Create the result set object– ResultSet rs = null

• Execute your select– rs = st.execute("select * from mytable");

• Loop through results:while (rs.next()){

int num = rs.getInt("numColumn");String word = rs.getString("name");}

Summary

• What is SQL• How to open a database• How to create tables• How to query tables – very, very basic• How to switch database context• Using SQL with Java