Database Select

Database Select is a feature of CodeIgniter Database that allows for the selection of data from a database table. With Database Select, users can retrieve data from a database table based on certain conditions.

Syntax

The basic syntax for Database Select is as follows:

$this->db->select('column_name_1, column_name_2');
$this->db->from('table_name');
$this->db->where('condition_1', 'condition_2');
$query = $this->db->get();
return $query->result();

In the above example, column_name_1 and column_name_2 refer to the columns to be selected from the table_name table. The where clause specifies the conditions that must be met in order for the data to be retrieved. The get() function executes the query, and result() returns an array of objects containing the retrieved data.

Example

Consider the following database table named employees:

id	name	age	gender
1	John	28	Male
2	Jane	35	Female
3	Mark	42	Male

To select the name and age columns of all employees who are older than 30, the following code can be used:

$this->db->select('name, age');
$this->db->from('employees');
$this->db->where('age >', 30);
$query = $this->db->get();
return $query->result();

This will return the following output:

[
    {
        "name": "Jane",
        "age": "35"
    },
    {
        "name": "Mark",
        "age": "42"
    }
]

Explanation

In the example above, the select() function is used to specify that only the name and age columns should be retrieved from the employees table. The where() function specifies that only employees with an age greater than 30 should be selected. The get() function executes the query, and the result() function returns an array of objects containing the selected data.

Use

Database Select is a useful feature of CodeIgniter Database that allows for the retrieval of data from a database table based on specified conditions. It is particularly useful when you need to retrieve specific pieces of data from a large table.

Important Points

• Queries using Database Select must be properly formatted to avoid SQL injection attacks.
• Database Select can be combined with other CodeIgniter functions such as limit() and order_by() for more precise querying.
• Resulting data can be returned as an array or as an object.

Summary

Database Select is a feature of CodeIgniter Database that allows for the retrieval of data from a database table based on specified conditions. Queries must be properly formatted to avoid SQL injection attacks, and can be combined with other CodeIgniter functions for more precise querying. Resulting data can be returned as an array or as an object.