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Database
- mysql
장은영
[email protected]
Contents

Database
– DBMS
– Relational model

SQL
– MySQL
Database

Database
– a collection of data
– Entity, relationship

DBMS
– Database management system
DBMS

Why use a DBMS?
–
–
–
–
–
efficient access
reduced application development time
data integrity and security
concurrent access
recovery from system crash
Relational model
Most widely used data model
 Relation

– A set of records
– Schema
• Name of a relation, name of each fields
– Instance
• A table with rows and columns
Students(sid:string, sname:string, snum:integer)
Fields (attributes, columns)
Field names
Tuples
(records, rows)
sid
sname
snum
euny
Chang Eun Young
99
cavalist Ryu Han Seung
99
netj
00
Jaeho Shin
SQL
Structured query language
 Standard language for interacting
with a DBMS
 Data definition
 Manipulation

MySQL

Connect
– mysql [–h host] [–u user] [–p[password]]
[dbname]
>mysql -u euny -p test
Enter password: ********
Welcome to the MySQL monitor. Commands end with ;
or \g.
Your MySQL connection id is 14 to server version:
3.23.34a
Type 'help;' or '\h' for help. Type '\c' to clear
the buffer
mysql>
MySQL

Data definition
– CREATE/DROP DATABASE dbname;
– SHOW DATABASES;
– USE dbname;
– CREATE TABLE table_name (field_name type,..,
constraints,..);
– SHOW TABLES;
– SHOW COLUMNS FROM table_name;
– DROP TABLE table_name;
MySQL

Data manipulation
– INSERT INTO table_name [(field_name,..)]
VALUES (value,..);
– DELETE FROM table_name
WHERE condition;
– UPDATE table_name
SET field_name=value,..
[WHERE condition];
MySQL

Data manipulation(2)
– SELECT field_name [as field_name],..
FROM table_name
[WHERE condition]
[ORDER BY field_name];
– =, <, >, AND, OR, NOT
(field_name LIKE “_%….”)
MySQL

ALTER TABLE
– ALTER TABLE table_name
[RENAME new_table_name]/
[ADD field_name type]/
[DROP field_name]/
[CHANGE name new_name new_type];
mysql> show databases;
+----------+
| Database |
+----------+
| mysql
|
| test
|
+----------+
2 rows in set (0.00 sec)
mysql> use test;
Database changed
mysql> create database test2;
Query OK, 1 row affected (0.00 sec)
mysql> CREATE TABLE Students(
-> sid VARCHAR(8) NOT NULL,
-> sname VARCHAR(20),
-> snum INT,
-> PRIMARY KEY(sid));
Query OK, 0 rows affected (0.01 sec)
•Data Type :
•CHAR, VARCHAR, INT [Unsigned], FLOAT
•DATE, TEXT/BLOB, SET, ENUM
•Constraints :
•PRIMARY/FOREIGN KEY, NOT NULL
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| students
|
+----------------+
1 row in set (0.00 sec)
mysql> show columns from students;
+-------+-------------+------+-----+---------+-------+
| Field | Type
| Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| sid
| varchar(8) |
| PRI |
|
|
| sname | varchar(20) | YES |
| NULL
|
|
| snum | int(11)
| YES |
| NULL
|
|
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.01 sec)
mysql> INSERT INTO Students
-> VALUES ('euny', 'Chang Eun-young', 99);
Query OK, 1 row affected (0.00 sec)
…
mysql> SELECT * FROM Students;
+----------+-----------------+------+
| sid
| sname
| snum |
+----------+-----------------+------+
| euny
| Chang Eun-young |
99 |
| cavalist | Ryu Han Seung
|
99 |
| netj
| Jaeho Shin
| 2000 |
+----------+-----------------+------+
3 rows in set (0.00 sec)
mysql> DELETE FROM Students
-> WHERE sid='euny';
Query OK, 1 row affected (0.00 sec)
mysql> UPDATE Students
-> SET sid='asdf'
-> WHERE sid='euny';
Query OK, 1 row affected (0.00 sec)
mysql> SELECT * FROM Students;
+----------+-----------------+------+
| sid
| sname
| snum |
+----------+-----------------+------+
| asdf
| Chang Eun-young |
99 |
| cavalist | Ryu Han Seung
|
99 |
| netj
| Jaeho Shin
| 2000 |
+----------+-----------------+------+
1 row in set (0.00 sec)
mysql> SELECT * FROM Students ORDER BY sname;
+----------+-----------------+------+
| sid
| sname
| snum |
+----------+-----------------+------+
| asdf
| Chang Eun-young |
99 |
| netj
| Jaeho Shin
| 2000 |
| cavalist | Ryu Han Seung
|
99 |
+----------+-----------------+------+
3 rows in set (0.02 sec)
mysql> SELECT sname FROM Students WHERE snum=99;
+-----------------+
| sname
|
+-----------------+
| Chang Eun-young |
| Ryu Han Seung
|
+-----------------+
1 row in set (0.00 sec)