13-Php and Mysql

7/31/2019 13-Php and Mysql

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PHP and MySQL

John Ryan B. Lorca

Instructor I

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Introduction to MySQL

SQL is a standard computer language for accessingand manipulating databases.

SQL stands for Structured Query Language

SQL allows you to access a database

SQL is an ANSI standard computer language

SQL can execute queries against a database

SQL can retrieve data from a database

SQL can insert new records in a database

SQL can delete records from a database

SQL can update records in a database

SQL is easy to learn

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SQL is an ANSI (American National Standards Institute)standard computer language for accessing andmanipulating database systems. SQL statements are usedto retrieve and update data in a database. SQL works withdatabase programs like MS Access, DB2, Informix, MS SQLServer, Oracle, Sybase, etc.

Unfortunately, there are many different versions of the SQLlanguage, but to be in compliance with the ANSI standard,they must support the same major keywords in a similarmanner (such as SELECT, UPDATE, DELETE, INSERT, WHERE,and others).

Note: Most of the SQL database programs also have theirown proprietary extensions in addition to the SQLstandard!

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SQL links

Tutorials http://www.w3schools.com/sql/

http://www.sqlzoo.net

http://sqlcourse.com (part 2) http://sqlcourse2/com (part 1)

MySQL online reference manual

http://dev.mysql.com/doc/mysql/en/Reference.html

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http://www.w3schools.com/sql/http://www.sqlzoo.net/http://sqlcourse.com/http://sqlcourse2/comhttp://dev.mysql.com/doc/mysql/en/Reference.htmlhttp://dev.mysql.com/doc/mysql/en/Reference.htmlhttp://sqlcourse2/comhttp://sqlcourse.com/http://www.sqlzoo.net/http://www.w3schools.com/sql/http://www.w3schools.com/sql/


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SQL Database Tables

A database most often contains one or more tables. Each table isidentified by a name

(e.g. "Customers" or "Orders"). Tables contain records (rows) withdata.

Below is an example of a table called "Persons":

The table above contains three records (one for each person) andfour columns

(LastName, FirstName, Address, and City).

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With SQL, we can query a database and have a

result set returned.

A query like this:

Gives a result set like this:

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WARNING Always assume that everything is case sensitive,

especially table names.

This is not the case in Windows XP but it is thecase in Linux

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Entering commands (1)

Show all the databases SHOW DATABASES;

mysql> SHOW DATABASES;

+-------------+| Database |

+-------------+

| bookstore |

| employee_db |

| mysql || student_db |

| test |

| web_db |

+-------------+

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Choosing a database and showing its tables USE test;

SHOW tables;

mysql> USE test;Database changed

mysql> SHOW tables;

+----------------+

| Tables_in_test |

+----------------+

| books |

| name2 || names |

| test |

+----------------+

4 rows in set (0.00 sec)

mysql>

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Database concepts (1)

A relational database management systemconsists of a number of databases.

Each database consists of a number of tables.

Example table

isbn title author pub year price

bookstable

rows

(records)

column

headings

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Some SQL data types (1)

Each entry in a row has a type specified by thecolumn.

Numeric data types

TINYINT, SMALLINT, MEDIUMINT, INT, BIGINT

FLOAT(display_length, decimals)

DOUBLE(display_length, decimals) DECIMAL(display_length, decimals)

NUMERIC is the same as DECIMAL

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Some SQL data types (2)

Date and time types DATE

format is YYYY-MM-DD

DATETIME

format YYYY-MM-DD HH:MM:SS

TIMESTAMP

format YYYYMMDDHHMMSS

TIME

format HH:MM:SS

YEAR

default length is 4

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SQL data types (3)

String types CHAR

fixed length string, e.g., CHAR(20)

VARCHAR variable length string, e.g., VARCHAR(20)

BLOB, TINYBLOB, MEDIUMBLOB, LONGBLOB

same as TEXT, TINYTEXT ...

ENUM

list of items from which value is selected

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SQL commands SHOW, USE

SHOW Display databases or tables in current database;

Example (command line client):

show databases; show tables;

USE

Specify which database to use Example

use bookstore;

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Introduction to MySQL Data

Definition Language CREATE creates a database table

CREATE TABLE table_name

(

column_name1 column_type1,column_name2 column_type2,

...

column_nameN column_typeN

);

Note: To create a database use the statement

CREATE db_name;

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Definition Language Specifying primary keys


(

column_name1 column_type1 NOT NULLDEFAULT '0',

column_name2 column_type2,

...

column_nameN column_typeN,PRIMARY KEY (column_name1)

);

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Definition Language

autoincrement primary integer keys


( column_name1 column_type1 PRIMARY

KEY NOT NULL DEFAULT '0'

AUTO_INCREMENT,

column_name2 column_type2,...

column_nameN column_typeN,

);

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Definition Language

Can also create UNIQUE keys. They are similar to PRIMARY KEYS

but can have NULL values.

Can also create INDEX fields.

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Manipulation Language

SQL Data Manipulation Language (DML)

SQL (Structured Query Language) is a syntax forexecuting queries. But the SQL

language also includes a syntax to update, insert, and

delete records. These query and update commands together form the

Data Manipulation Language

(DML) part of SQL:

SELECT - extracts data from a database table UPDATE - updates data in a database table

DELETE - deletes data from a database table

INSERT INTO - inserts new data into a database table

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The SQL SELECT Statement Syntax

The SELECT statement is used to select data

from a table. The tabular result is stored in a

result table (called the result-set).

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Manipulation LanguageThe SQL SELECT Statement Example

To select the content of columns named "LastName" and "FirstName",

from the database table called "Persons", use a SELECT statement like this:

The database table "Persons":

The result

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Select All Columns

To select all columns from the "Persons" table,

use a * symbol instead of column names, like

this:

Result

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The SELECT DISTINCT Statement Syntax

The DISTINCT keyword is used to return only distinct

(different) values.

The SELECT statement returns information from tablecolumns. But what if we only want to select distinct

elements?

With SQL, all we need to do is to add a DISTINCT

keyword to the SELECT statement:

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Manipulation LanguageUsing the DISTINCT keyword

To select ALL values from the column named "Company" we use a SELECT

statement

like this:

"Orders" table

Results

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Manipulation LanguageUsing the DISTINCT keyword

Note that "W3Schools" is listed twice in the result-set.

To select only DIFFERENT values from the column named "Company" we use a

SELECT DISTINCT statement like this:

Result

Now "W3Schools" is listed only once in the result-set.

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Manipulation LanguageThe WHERE Clause - Syntax To conditionally select data from a table, a WHERE clause can be added to

the SELECT statement.

With the WHERE clause, the following operators can be used:

Note: In some versions of SQL the operator may be written as != 30


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Manipulation LanguageUsing the WHERE Clause

To select only the persons living in the city "Sandnes", we add a WHERE

clause to the SELECT statement:

"Persons" table

Result

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Manipulation LanguageUsing Quotes Note that we have used single quotes around the conditional values in the

examples.

SQL uses single quotes around text values (most database systems will also

accept

double quotes). Numeric values should not be enclosed in quotes. For text values:

For numeric values:

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The LIKE Condition - Syntax The LIKE condition is used to specify a search for

a pattern in a column.

A "%" sign can be used to define wildcards(missing letters in the pattern) both before andafter the pattern.

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Manipulation LanguageUsing LIKE

The following SQL statement will return persons with first names that start

with an 'O':

The following SQL statement will return persons with first names that end

with an 'a':

The following SQL statement will return persons with first names that

contain the pattern 'la':

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The INSERT INTO Statement Syntax

The INSERT INTO statement is used to insert

new rows into a table.

You can also specify the columns for whichyou want to insert data:

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Insert a New Row

This "Persons" table:

And this SQL statement:

Will give this result:

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The Update Statement Syntax

The UPDATE statement is used to modify the

data in a table.

Person

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Update one Column in a Row

We want to add a first name to the person

with a last name of "Rasmussen":

Result

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Update several Columns in a Row

We want to change the address and add the

name of the city:

Result

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The DELETE Statement Syntax

The DELETE statement is used to delete rows

in a table.

Person

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Delete a Row

"Nina Rasmussen" is going to be deleted:

Result

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Delete All Rows

It is possible to delete all rows in a table

without deleting the table. This means that

the table structure, attributes, and indexes

will be intact:

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Manipulation LanguageSort the Rows

The ORDER BY clause is used to sort the rows.

Orders:

To display the company names in alphabetical order:

Result:

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Sort the Rows

To display the company names in alphabetical order

AND the OrderNumber in numerical order:

Result:

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Sort the Rows

To display the company names in reverse

alphabetical order:

Result:

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Manipulation LanguageSort the Rows To display the company names in reverse alphabetical order AND the

OrderNumber in numerical order:

Result:

Notice that there are two equal company names (W3Schools) in the result

above. The only time you will see the second column in ASC order would

be when there are duplicated values in the first sort column, or a handful

of nulls.

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AND & OR

AND and OR join two or more conditions in a

WHERE clause.

The AND operator displays a row if ALL

conditions listed are true. The OR operator

displays a row if ANY of the conditions listed

are true.

Original Table (used in the examples)

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AND & OR

Use AND to display each person with the first

name equal to "Tove", and the last name

equal to "Svendson":

Result:

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AND & OR

Use OR to display each person with the first

name equal to "Tove", or the last name equal

to "Svendson":

Result:

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AND & OR

You can also combine AND and OR (use

parentheses to form complex expressions):

Result:

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I t d ti t M SQL D t


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IN The IN operator may be used if you know

the exact value you want to return for at

least one of the columns.


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IN

To display the persons with LastName equal to

"Hansen" or "Pettersen", use the following

SQL:

Result:

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BETWEEN ... AND

The BETWEEN ... AND operator selects a range

of data between two values. These values can

be numbers, text, or dates.


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BETWEEN ... AND

To display the persons alphabetically between

(and including) "Hansen" and exclusive

"Pettersen", use the following SQL:

Result:

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Manipulation Language BETWEEN ... AND IMPORTANT!

The BETWEEN...AND operator is treated differently in different databases.

With some databases a person with the LastName of "Hansen" or"Pettersen" will not be listed (BETWEEN..AND only selects fields that arebetween and excluding the test values).

With some databases a person with the last name of "Hansen" or"Pettersen" will be listed (BETWEEN..AND selects fields that are betweenand including the test values).

With other databases a person with the last name of "Hansen" will belisted, but "Pettersen" will not be listed (BETWEEN..AND selects fieldsbetween the test values, including the first test value and excluding the

last test value). Therefore: Check how your database treats the BETWEEN....AND operator!

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BETWEEN ... AND

To display the persons outside the range used

in the previous example, use the NOT

operator:

Result:

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PHP and MySQL

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13-Php and Mysql

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