MySQL Tutorial 1 – How to Use MySQL

1. MySQL Tutorial 1 – How to Use MySQL CSCI 2140 TA: Jiye Li jiye@cs.dal.ca May 26, 2005 http://flame.cs.dal.ca/~jiye/CSCI2140/ MySQL Tutorial - 1

2. Agenda • Getting familiar with our network system • Introducing MySQL • SQL basics • create, add, select, modify, delete • Exercises (see handout) MySQL Tutorial - 1

3. How to get a UNIX account • Sun workstation or ssh program (putty) • Log into torch.cs.dal.ca • Username: discover • Passwd: query • Enter your student number • Ask Help Desk MySQL Tutorial - 1

4. How to get a Windows account • Username: the same as torch account • Password: student ID number. Don’t forget ‘B’ is capitalized. MySQL Tutorial - 1

5. What is MySQL? • MySQL is a database management system (DBMS) for relational databases • Online Manual • http://dev.mysql.com/doc/ • MySQL is installed on torch • Each user ID stands for a database • Create tables under this database MySQL Tutorial - 1

6. How to Login to MySQL • Go on torch.cs.dal.ca • Run mysql to login torch: ~$ mysql -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 123943 to server version: 4.0.12 Type 'help;' or '\h' for help. Type '\c' to clear the buffer. mysql> Lower case Student ID MySQL Tutorial - 1

7. How to Logout • Use the command exit or quit torch: ~$ mysql -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 123975 to server version: 4.0.12 Type 'help;' or '\h' for help. Type '\c' to clear the buffer. mysql> exit Bye torch: ~$ MySQL Tutorial - 1

8. Use your database • After login MySQL, use your own database before creating tables torch: ~$ mysql -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 125213 to server version: 4.0.12 Type 'help;' or '\h' for help. Type '\c' to clear the buffer. mysql> use jiye; Database changed mysql> Your user ID MySQL Tutorial - 1

9. SQL Basics • Suppose we would like to create a few tables, such as employee table, employer table and payment table, representing a database about employee information. MySQL Tutorial - 1

10. How to write commands in MySQL • How to create a table • Primary Keys and Foreign Keys • How to add records • How to select records • How to modify records • How to delete records MySQL Tutorial - 1

11. How to create tables • Use create create table <table_name> (column_name data_type [not null] … , column_name data_type [not null], primary key (column_name)); • To show the structure of the table describe <table_name>; MySQL Tutorial - 1

12. Example mysql> create table employee( empno smallint(4) not null auto_increment, name char (8) not null, job char (4) , salary int (8) not null, deptno int (4) not null, primary key (empno) ); MySQL Tutorial - 1

13. Primary Key • Primary Key is a column or set of columns • Uniquely identifies the rest of the data in any given row. For Example: in the employee table, employee number is the primary key. MySQL Tutorial - 1

14. Foreign Key • A foreign key is a column in a table • This column is a primary key of another table • Any data in a foreign key column must have corresponding data in the other table • http://dev.mysql.com/doc/mysql/en/innodb-foreign-key-constraints.html MySQL Tutorial - 1

15. Foreign Key • The goal of using foreign keys is that, tables can be related without repeating data • Note that foreign keys in SQL are used to check and enforce referential integrity, not to join tables. If you want to get results from multiple tables from a SELECT statement, you do this by performing a join between them: SELECT * FROM t1, t2 WHERE t1.id = t2.id; MySQL Tutorial - 1

16. Example – Create table with foreign keys employee2 create table employee2( empno smallint(4) not null, salary float, primary key (empno) ) type = innodb; create table employer ( id smallint(4), employee_no smallint(4), index employ_ind (employee_no), foreign key(employee_no) references employee2(empno) on delete cascade) type=innodb; employer MySQL Tutorial - 1

17. The Syntax of a Foreign Key Constraint Definition [CONSTRAINT [symbol]] FOREIGN KEY (index_col_name, ...) REFERENCES table_name (index_col_name, ...) [ON DELETE {CASCADE | SET NULL | NO ACTION | RESTRICT}] [ON UPDATE {CASCADE | SET NULL | NO ACTION | RESTRICT}] • Both tables have to be InnoDB type • InnoDB provides MySQL with a transaction-safe storage engine with commit, rollback, and crash recovery capabilities. http://dev.mysql.com/doc/mysql/en/innodb-overview.html MySQL Tutorial - 1

18. The Syntax of a Foreign Key Constraint Definition • InnoDB rejects any INSERT or UPDATE operation that attempts to create a foreign key value in a child table without a matching candidate key value in the parent table. • CASCADE: Delete or update the row from the parent table and automatically delete or update the matching rows in the child table. • SET NULL: Delete or update the row from the parent table and set the foreign key column(s) in the child table to NULL. This is only valid if the foreign key columns do not have the NOT NULL qualifier specified. • NO ACTION: NO ACTION means no action in the sense that an attempt to delete or update a primary key value will not be allowed to proceed if there is a related foreign key value in the referenced table. • RESTRICT: Rejects the delete or update operation for the parent table. NO ACTION and RESTRICT are the same as omitting the ON DELETE or ON UPDATE clause. (Some database systems have deferred checks, and NO ACTION is a deferred check. In MySQL, foreign key constraints are checked immediately, so NO ACTION and RESTRICT are the same.) • SET DEFAULT: This action is recognized by the parser, but InnoDB rejects table definitions containing ON DELETE SET DEFAULT or ON UPDATE SET DEFAULT clauses. MySQL Tutorial - 1

19. MySQL Table Types • If we want to use Foreign Key • InnoDB tables • Otherwise • Default table type, MyISAM • In SQL queries you can freely mix InnoDB type tables with other table types of MySQL, even within the same query. MySQL Tutorial - 1

20. How to add records • Use insert insert into <table_name> values (column_value, …, column_value); MySQL Tutorial - 1

21. Example insert into employee values (1000,'Wilson','Clrk',1700,10); insert into employee values (1001,'Smith','Slsm',2500,40); insert into employee values (1003,'Reed','Anlt',3500,30); insert into employee values (1005,'Watson','Mngr',4500,30); insert into employee values (1009,'Allen','Mngr',3800,40); insert into employee values (1010,'Turner','Clrk',1800,50); insert into employee values (2000,'Chen','Mngr',2900,10); insert into employee values (2100,'Ramirez','Mngr',3650,50); insert into employee values (2130,'McDonnel','Clrk',1625,60); insert into employee values (2140,'Simpson','Drvr',825,60); MySQL Tutorial - 1

22. Example On Slide 17 insert into employee2 values (100, 200.85); insert into employee2 values (200, 129.54); insert into employee2 values (300, 98.17); insert into employer values (51, 100); insert into employer values (52, 100); insert into employer values (53, 200); insert into employer values (54, 300); MySQL Tutorial - 1

23. How to Select Records • select * from <table_name>; • select * from <table_name> where <column_name> = <qualifier>; • select * from <table_name> where <column_name> = <qualifier> order by <column_name>; • select <column_name, …> from <table_name>; • select <distinct column_name, …> from <table_name> MySQL Tutorial - 1

24. Example select * from employee; select * from employee where empno = 1000; select * from employee where job = 'Clrk' order by salary; select name, empno from employee; select job from employee; select distinct job from employee; MySQL Tutorial - 1

25. Example On Slide 17 select empno from employee2; select empno from employee2 where salary >=50 and salary < 150; select * from employee2, employer; select id, empno from employer m, employee2 n where m.employee_no = n.empno; MySQL Tutorial - 1

26. How to Modify Records • Use update to modify attribute values of (some) tuples in a table update <table_name> set <column i > = <expression i>, …, <column j> = <expression j> [where <condition>]; MySQL Tutorial - 1

27. Example update employee set job = ‘Drvr’, deptno = 20 , salary = salary + 1000 where name = 'Reed’; update employee set salary = salary * 1.15 where deptno in (10, 40); MySQL Tutorial - 1

28. How to Delete Records • Use delete delete from <table_name> [where <condition>]; MySQL Tutorial - 1

29. Example delete from employee where salary < 2000; delete from employee; Note: this command will delete all the records in the “employee” table. MySQL Tutorial - 1

30. Tip1: How to Load Command • Execute a SQL script file. Take a file name as an argument. • Save SQL commands into a file <name> • Execute the commands: • mysql> source <name>; MySQL Tutorial - 1

31. Example • In file “temp.sql” select * from employee; select name from employee where salary < 3000; • mysql> source temp.sql; MySQL Tutorial - 1

32. Tip2: How to Save Results • Save results • tee <file> Set outfile. Append everything into given outfile <file>. All the information displayed on screen is stored in <file>. MySQL Tutorial - 1

33. Example mysql>tee result; mysql> select * from employee; mysql> notee; mysql> exit torch: ~$ cat result mysql> select * from employee; EMPNO NAME JOB SALARY DEPTNO ---------- -------- ---- ---------- ---------- 1000 Wilson Clrk 1720 10 1001 Smith Slsm 2500 40 ………… 10 rows selected. mysql> notee; torch: ~$ MySQL Tutorial - 1

34. Appendix: MySQL Data Types MySQL Tutorial - 1

35. Appendix: MySQL under Unix • A few commands • use username; • show tables; • show columns from employee; • help; • exit; • SQL commands (select, insert, delete,…) MySQL Tutorial - 1

36. Appendix: MySQL Control Center • Graphical user interface (GUI) to the MySQL database server • Supports interactive use, including syntax highlighting and tab completion • Download from • http://dev.mysql.com/downloads/other/mysqlcc.html MySQL Tutorial - 1

37. Appendix: MySQL Control Center Student ID MySQL Tutorial - 1