<Html>
<Body>
<Form action = submitform. php3 method = GET>
Last name: <input type = text name = first_name size = 25 maxlength = 25>
Name: <input type = text name = last_name size = 25 maxlength = 25>
<P>
<Input type = submit>
</Form>
</Body>
</Html>
After you enter the data and press the submit button, this form will send the data to submitform. php3. The PHP script then processes the received data. The following is the submitform. php3 code:
<Html>
<Body>
<? Php
Mysql_connect (localhost, username, password );
Mysql_select_db (dbname );
Mysql_query ("insert into tablename (first_name, last_name)
VALUES ('$ first_name', '$ last_name ')
");
Print ($ first_name );
Print ("");
Print ($ last_name );
Print ("<p> ");
Print ("Thank you for entering the registry ");
?>
</Body>
</Html>
In the third line of the code, "username" and "password" represent the account and password for logging on to the MySQL database respectively. "Dbname" in the fifth line indicates the name of the MySQL database. "Tablename" in row 13th is the name of a data table in the database.
After you press submit, you can see that the name you entered is displayed in a new page. Let's take a look at the URL bar of the browser. its content should be like this:
... /Submitform. php3? First_name = Fred & last_name = Flintstone
Because we use the form GET method, data is transmitted to submitform. php3 through URL. Obviously, the GET method has limitations. when there is a lot of content to be passed, you cannot use GET, but you can only use POST method. However, no matter what method is used, after data transmission is complete, PHP automatically creates a variable with the same name (name attribute of the form) for the fields in each form.
PHP variables start with a dollar sign. the $ first_name and $ last_name variables are generated during php3 script processing. the content of the variables is what you input.
Let's check whether the name you entered is actually input into the database. Start MySQL and enter:
Mysql> select * from tablename;
You should be able to get a table with the content you just entered:
+ ------------ +
| First_name | last_name |
+ ------------ +
| Liu | Ruifeng
+ ------------ +
1 rows in set (0.00 sec)
Let's analyze how submitform. php3 works:
The first two lines of the script are:
Mysql_connect (localhost, username, password );
Mysql_select_db (dbname );
The two function calls are used to open the MySQL database. the specific parameter meanings have been mentioned just now.
The following line executes an SQL statement:
Mysql_query ("insert into tablename (first_name, last_name)
VALUES ('$ first_name', '$ last_name ')
");
The mysql_query function is used to execute an SQL query for the selected database. You can execute any SQL statement in the mysql_query function. The executed SQL statement must be enclosed in double quotation marks as a string, and the variables must be enclosed in single quotation marks.
One thing to note: the MySQL statement should end with a semicolon (;). The same applies to a line of PHP code, but the MySQL statement in the PHP script cannot contain a semicolon. That is to say, when you enter the mysql command at the MySQL> prompt, you should add a semicolon:
Insert into tablename (first_name, last_name)
VALUES ('$ first_name', '$ last_name ');
However, if this command appears in a PHP script, remove the semicolon. This is because some statements, such as SELECT and INSERT, can work with or without semicolons. However, there are still some statements, such as UPDATE, which won't work if you add a semicolon. To avoid trouble, remember this rule.
How PHP extracts data from MySQL
Now we create another HTML form to execute this task:
<Html>
<Body>
<Form action = searchform. php3 method = GET>
Enter your query content:
<P>
Last name: <input type = text name = first_name size = 25 maxlength = 25>
<P>
Name: <input type = text name = last_name size = 25 maxlength = 25>
<P>
<Input type = submit>
</Form>
</Body>
</Html>
Similarly, we need a php script to process this form. we will create another searchform. php3 file:
<Html>
<Body>
<? Php
Mysql_connect (localhost, username, password );
Mysql_select_db (dbname );
If ($ first_name = "")
{$ First_name = '% ';}
If ($ last_name = "")
{$ Last_name = '% ';}
$ Result = mysql_query ("SELECT * FROM tablename
WHERE first_name LIKE '$ first_name %'
AND last_name LIKE '$ last_name %'
");
If ($ row = mysql_fetch_array ($ result )){
Do {
Print $ row ["first_name"];
Print ("");
Print $ row ["last_name"];
Print ("<p> ");
} While ($ row = mysql_fetch_array ($ result ));
} Else {print "Sorry, no matching record found in our database. ";}
?>
</Body>
</Html>
After you enter the content to be retrieved in the form and then press the SUBMIT button, a new page is displayed, listing all matching search results. Next let's take a look at how this script completes the search task.
The preceding statements are the same as described above. first, a database connection is established, and then a database and a data table are selected. these are required for each database application. Then there are several statements:
If ($ first_name = "")
{$ First_name = '% ';}
If ($ last_name = "")
{$ Last_name = '% ';}
These rows are used to check whether the fields in the form are empty. Note that the two equal signs, because most PHP syntax comes from the C language. here the equal signs are used in the same way as C: an equal sign is a value assignment, and two equal signs represent logical equals. It should also be noted that when the condition after IF is true, the following statements to be executed are placed in "{" and, in addition, each statement must be followed by a semicolon to end the statement.
Percent sign % is a wildcard in the SQL language. after understanding it, you should know the meaning of the two rows: if the "FIRST_NAME" field is blank, all FIRST_NAME will be listed. The following two sentences also mean the same.
$ Result = mysql_query ("SELECT * FROM tablename
WHERE first_name LIKE '$ first_name %'
AND last_name LIKE '$ last_name % '"
");
This line completes most of the search work. After the mysql_query function completes a query, it returns an integer sign.
The query selects records from all records that have the same first_name and $ first_name variables, and the last_name column and $ last_name variable values, and puts them in the saved record set, use the returned integer as the flag of this record set.
If ($ row = mysql_fetch_array ($ result )){
Do {
Print $ row ["first_name"];
Print ("");
Print $ row ["last_name"];
Print ("<p> ");
} While ($ row = mysql_fetch_array ($ result ));
} Else {print "Sorry, no matching record found in our database. ";}
This is the last step, that is, the display part. The mysql_fetch_array function extracts the content of the first row of the query result and displays it in PRINT statements. The parameter of this function is the integer sign returned by the mysql_query function. After mysql_fetch_array is successfully executed, the record set pointer will be automatically moved down, so when mysql_fetch_array is executed again, the content of the next record will be obtained.
The array variable $ row is created by the mysql_fetch_array function and filled with the query result field. each component of the array corresponds to each field in the query result.
If a matching record is found and the variable $ row is not empty, the statement in curly brackets is executed:
Do {
Print $ row ["first_name"];
Print ("");
Print $ row ["last_name"];
Print ("<p> ");
} While ($ row = mysql_fetch_array ($ result ));
This is a do... While loop. Unlike the while loop, it executes the loop body once first, and then checks whether the loop conditions are met. As we already know that when the record set is not empty, we must at least execute the loop body. so we should use do... While instead of while loop. In curly braces, it is the body of the loop to be executed:
Print $ row ["first_name"];
Print ("");
Print $ row ["last_name"];
Print ("<p> ");
Then, check whether the while condition is met. The Mysql_fetch_array function is called again to obtain the content of the current record. This process continues cyclically. If no record exists, mysql_fetch_array returns false. when the loop ends, the record set is completely traversed.
The array returned by mysql_fetch_array ($ result) can be called by field names or subscripts to reference each component of the array, just like an ordinary array. In this way, the above code can also be written as follows:
Print $ row [0];
Print ("");
Print $ row [1];
Print ("<p> ");
We can also use the echo function to compact these four statements:
Echo $ row [0], "", $ row [1], "<p> ";
When no matching record is found, no content exists in $ row. in this case, the else clause of the if statement is called:
Else {print "Sorry, no matching record found in our database. ";}
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