How to use SQLite functions in PHP

With the increasing development of Internet technology, more and more websites and applications require data storage and management. In this regard, relational databases are very important tools that can help developers store and manage data in a fixed format. Currently, the mainstream relational databases include MySQL, Oracle, SQL Server, PostgreSQL, etc. However, for some lightweight applications, using a database such as MySQL is a bit too heavy, and in this case a lighter database is needed.

SQLite is a lightweight database that allows developers to easily embed data storage and management functions in applications. It is an open source relational database system, a fully documented database that can be operated without a network connection. In PHP, we can use SQLite functions to operate on the SQLite database. Below we will introduce in detail how to use SQLite functions in PHP.

1. Open SQLite database

First, we need to open a SQLite database so that we can operate on the database. It is very simple to open a SQLite database using PHP. You only need to call the sqlite_open function in PHP that is specially used to open a SQLite database. The sqlite_open function has two parameters. The first parameter is the name of the SQLite database, and the second parameter is the permission setting parameter. The specific usage is as follows:

$db = sqlite_open("testDB.db", 0666, $error);

In the above example code, we opened a SQLite database named testDB.db and set read and write permissions (0666) for it. If the opening fails, $error will Save error message.

2. Create SQLite table

Creating a table is an important operation of SQLite database. Although SQLite database is simpler than MySQL and other databases, we still need to First create a table to store data. For the operation of creating a table, we can use SQL statements to operate. In SQLite, one of the very basic SQL statements to create a table is:

CREATE TABLE tableName (
    column1Type column1Name,
    column2Type column2Name,
    ...
);

Among them, tableName represents the name of the table, column1Type and column2Type represent the type of the column, and column1Name and column2Name are the names of the columns. The following is a specific sample code:

$sql = "
        CREATE TABLE users (
            user_id INTEGER PRIMARY KEY,
            user_name TEXT,
            user_email TEXT
        );
";
$result = sqlite_exec($db, $sql);

In the above sample code, we created a table named users. The table has three columns, namely user_id, user_name and user_email. Among them, user_id is set PRIMARY KEY.

3. Query SQLite table data

The data saved in the SQLite table can be queried through SQL statements. The following is an example of querying table data:

$sql = "SELECT * FROM users";
$result = sqlite_query($db, $sql);
while($row = sqlite_fetch_array($result)){
    echo $row['user_name'] . "<br/>";
}

In the above example code, we used the SELECT statement to query the users table and output the queried data to the web page.

4. Insert SQLite database data

Inserting data is also a very common operation in SQLite database. The following is an example of inserting data:

$sql = "INSERT INTO users (user_name, user_email) VALUES ('Tom', 'tom@example.com')";
$result = sqlite_exec($db, $sql);

In the above example code, we inserted a new piece of data into the users table, where user_name is Tom and user_email is tom@example.com.

5. Modify SQLite database data

Modifying data is also one of the common operations. The following is a simple example:

$sql = "UPDATE users SET user_email = 'new@example.com' WHERE user_id = 1";
$result = sqlite_exec($db, $sql);

In the above example code, We use the UPDATE statement to modify the user_email value of the record with ID 1 in the users table.

6. Delete SQLite database data

Deleting data is also a very common operation in SQLite database. The following is an example:

$sql = "DELETE FROM users WHERE user_name = 'Tom'";
$result = sqlite_exec($db, $sql);

In the above example code, we used the DELETE statement to delete the record whose user_name is Tom in the users table.

Summary:

Using SQLite functions in PHP to operate SQLite databases is very simple and easy to use. Using SQLite allows us to easily develop some lightweight applications without installing complex relational database software. SQLite is also widely used in mobile development due to its lightweight and efficient characteristics. I hope this article can be helpful to everyone when using SQLite database.

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