PHP&MYSQL review outline_PHP tutorial

PHP&MYSQL review outline 1

1. PHP syntax

◆ Data type

PHP has only three basic data types: integers, floating point numbers (or real numbers, double precision numbers) and strings. Strings can use single quotes and double quotes, but they have different meanings: variables can only be used within double quotes.

◆ Variables

Add "$" in front of the variable. When using a variable, you do not need to specify (or define) the type of the variable in advance. Different types of data can be assigned to the same variable. But if you want to use global variables, you must use global instructions (or add them to the $GLOBALS[] array). To use static variables, use static instructions.

◆ Array

Using an array does not require specifying its type and size, it can be used directly. Elements of the same array can have different data types.

◇ Scalar array

Use the following assignment statement to generate a scalar array:

　$a[0]=100;
​$a[1]="Hello";
​$a[2]=23.4;

If the subscript is omitted, the subscript values ​​will be automatically arranged in order.

◇ Associative array

Use the following assignment statement to generate an associative array:

　$students[name]= 'Zhang San';
​$students[age]= 20;
​$students[tel]= '65032905-8097';

When accessing the database, a record can be used as an associative array, with the field name in square brackets.

◆ Operator

Generally retains the operators of C language. Added string concatenation character "." (use "->" when accessing object members). Added "=>" operator, used to assign initial value to array. In addition, logical AND ("&&") and logical OR ("||") can also be used with "and" and "or", and logical exclusive OR "xor" is added.

◆ Basic sentences

It is required to master the if-else statement, switch-case statement, for statement, while statement, do-while statement, continue statement, and break statement. require statement and include statement, used to insert a disk file. The difference is: if used in a conditional statement, include only inserts the file when the condition is met, while require always inserts. The format is:

include("file name");
require("file name");

◆ Definition and use of functions

Use function to define a function without specifying the function type and parameter type.

Function function name (parameter 1, parameter 2,...)
{ Statement 1;
Statement 2;......
}

It is allowed to add "&" before the parameters so that the parameters can transfer data in both directions. It is also allowed to assign default values ​​to parameters.

2. MYSQL syntax

Numeric type

Column type

Amount of storage required

TINYINT

1 byte

SMALLINT

2 bytes

MEDIUMINT

3 bytes

INT

4 bytes

INTEGER

4 bytes

BIGINT

8 bytes

FLOAT(X)

4 if X < = 24 or 8 if 25 < = X < = 53

FLOAT

4 bytes

DOUBLE

8 bytes

DOUBLE PRECISION

8 bytes

REAL

8 bytes

DECIMAL(M,D)

M bytes (D+2, if M < D)

NUMERIC(M,D)

M bytes (D+2, if M < D)

Date and time types
Column type

Amount of storage required

DATE

3 bytes

DATETIME

8 bytes

TIMESTAMP

4 bytes

TIME

3 bytes

YEAR

1 byte

String type
Column type

Amount of storage required

CHAR(M)

M bytes, 1 <= M <= 255

VARCHAR(M)

L+1 bytes, where L <= M and 1 <= M <= 255

TINYBLOB, TINYTEXT

L+1 bytes, here L< 2 ^ 8

BLOB, TEXT

L+2 bytes, where L< 2 ^ 16

MEDIUMBLOB, MEDIUMTEXT

L+3 bytes, here L< 2 ^ 24

LONGBLOB, LONGTEXT

L+4 bytes, where L< 2 ^ 32

ENUM('value1','value2',...)

1 or 2 bytes, depending on the number of enumeration values ​​(maximum 65535)

SET('value1','value2',...)

1, 2, 3, 4 or 8 bytes, depending on the number of set members (up to 64 members)

1. Create a new database

CREATE　DATABASE　Database name

2. Display database

SHOW　DATABASES

3. Open the database

USE database name

4. Display the tables in the database

SHOW　TABLES

5. Display table structure

DESCRIBE table name or SHOW COLUMNS FROM table name

6. Create table

CREATE　TABLE　Table name (field name Data type (data size) [NOT　NULL][PRIMARY KEY[AUTO＿INCREMENT]],...)

7. Modify table

A. Add new domain

Format: ALTER TABLE table name ADD COLUMN field name data type (data size) NOT NULL...

B. Modify domain

Format: ALTER TABLE table name CHANGE COLUMN field name field definition

C. Delete domain

Format: ALTER TABLE table name DROP COLUMN domain name

8. Delete table

Format: DROP　TABLE　Table name

9. Select query

Format: SELECT Domain name [AS Domain alias]...FROM Table name [WHERE Condition][GROUP BY...][HAVING...][ORDER BY...]

10. Add a single record

insert into table name (field 1, field 2,...) values ​​(value 1, value 2,...)

11. Add multiple records

insert into　table name (field 1, field 2,...) select field from　table where condition;

12. Update record

update table name set field name = new value where condition

13. Delete records

delete from table name where condition

3. Examples

1． IF…ELSE program

Please enter your gender:

Male

Female

if ($gender=="woman")

echo "

Hello, Miss

";

else

echo "<>Hello Sir

";

?>

2． IF…ELSEIF…ELSE program

Operator 1:

Operator 2:

What operation do you want to perform?

add

minus

Multiply

except

Result:

Equals

if ($operation == "Add")

{$x = $num1 + $num2;

print $x;}

elseif ($operation == "Minus")

{$x = $num1 - $num2;

print $x;}

elseif ($operation == "Multiple")

{$x = $num1 * $num2;

print $x;}

elseif ($operation == "except")

{$x=$num1/$num2;

print $x;}

else

print $x;

?>

3. for loop program

$sum=0;

for ($i=1; $i<=100; $i++) //Enter the loop

{

$sum+=$i; //Execute once to add $sum to $i

}

echo $sum; //Display results

?>

4． while program

$sum=0;

while ($i<=100)                                                       

{

$sum+=$i;

$i++;

};

echo $sum;

?>

5． do … while program

What is the upper limit of summation?

$sum=0; $i=1;

do {                                                                  

$sum+=$i;

$i++;

}

while ($i<=$up);                               

echo "Start from 1 and add to".($i-1);

echo "
";

echo "The sum is".$sum;

?>

6． Function routine

function cal ($cal_nu)                                              

{

$cal_sqr=$cal_nu*$cal_nu;

$cal_cub=$cal_nu*$cal_nu*$cal_nu;

return array($cal_sqr, $cal_cub);

}

?>

Please enter a number

list($sqr, $cub) = cal($nu_input);

echo $nu_input; echo "The square of "is:"; echo $sqr;

echo "
";

echo $nu_input; echo "The cube of " is: "; echo $cub;

?>

7． Create data table

mysql_connect("localhost","s990402","zq");

mysql_select_db("s990402");

$str="CREATE TABLE students(

id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,

name CHAR(10),

age INT,

tel VARCHAR(20),
​addr VARCHAR(30)

)";
$result=mysql_query($str);

if($result)
echo "Data table "students" created successfully!";
else

echo "Data table creation failed!";

?>
8． Add record

$cn=mysql_connect("localhost","s990402","zq");
mysql_select_db("s990402",$cn);
$ins=mysql_query("INSERT INTO students(nam,age,tel,addr)

VALUES('$nam',$age,'$tel','$addr')",$cn);

if($ins)

echo "New records have been added to the database.";

else
echo "Record addition failed.";
?>

9． Browsing history

mysql_connect("localhost","s990402","zq");
mysql_select_db("s990402");
$q=mysql_query("SELECT * FROM students ORDER BY age DESC");
while($a=mysql_fetch_array($q))
　　print "
　　　　"
?>

姓名	年龄	电话	住址
$a[name]	$a[age]	$a[tel]	$a[addr]

10． 删除记录(本程序文件名为del.php)

$cn=mysql_connect("localhost","s990402","zq");
mysql_select_db("s990402",$cn);
if($id>0) mysql_query("DELETE FROM students WHERE id=$id",$cn);
?>

$q=mysql_query("SELECT * FROM students ORDER BY age DESC",$cn);
while($a=mysql_fetch_array($q))
　print "
　　　
　　　"
?>

	姓名	年龄	电话	住址
删除	$a[nam]	$a[age]	$a[tel]	$a[addr]

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