Data manipulation in MySQL is an essential task for any database developer. MySQL is an open source relational database management system (RDBMS) that uses the Structured Query Language (SQL) to access, add, manage, and manipulate data.
There are four basic data manipulation operations in MySQL: SELECT, INSERT, UPDATE, and DELETE. These operations are often referred to as CRUD (Create, Read, Update, Delete).
SELECT
The SELECT command is used to retrieve data from one or more tables. The basic syntax is:
SELECT column_name1, column_name2, ... FROM table_name;
You can select all columns using the asterisk (*) instead of listing all columns. For example:
SELECT * FROM table_name;
The SELECT statement can be combined with various clauses, such as WHERE, GROUP BY, HAVING, ORDER BY, to filter, group, and order the retrieved data.
INSERT
The INSERT command is used to insert new records into a table. The basic syntax is:
INSERT INTO table_name (column1, column2, column3, ...) VALUES(value1, value2, value3, ...);
If you are entering values for all columns in the table, you do not need to specify column names. For example:
INSERT INTO table_name VALUES(value1, value2, value3, ...);
UPDATE
The UPDATE command is used to update existing records in a table. The basic syntax is:
UPDATE table_name SET column1 = value1, column2 = value2, ... WHERE condition;
The WHERE clause is very important in the UPDATE statement. If you omit the WHERE clause, all records in the table will be updated!
DELETE
The DELETE command is used to delete existing records in a table. The basic syntax is:
DELETE FROM table_name WHERE condition;
Like the UPDATE statement, the WHERE clause is very important in the DELETE statement. If you omit the WHERE clause, all records in the table will be deleted!
Data Manipulation with PHP and MySQL
MySQL is often used with PHP to create dynamic web applications. Here is an example of how you can use PHP to connect to a MySQL database and manipulate data.
connect_error) {
die("Connection failed: " . $conn->connect_error);
}
// sql to create table
$sql = "CREATE TABLE MyGuests (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP
)";
if ($conn->query($sql) === TRUE) {
echo "Table MyGuests created successfully";
} else {
echo "Error creating table: " . $conn->error;
}
$conn->close();
?>
In summary, data manipulation in MySQL is an essential skill for any database developer. With practice, you will become proficient in using the SELECT, INSERT, UPDATE, and DELETE commands to manipulate data in MySQL.
