Урок - Поле данных.

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CodeIgniter® 2.2

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$this->db->list_fields()

Returns an array containing the field names. This query can be called two ways:

1. You can supply the table name and call it from the $this->db-> object:

$fields = $this->db->list_fields('table_name');

foreach ($fields as $field)
{
   echo $field;
}

2. You can gather the field names associated with any query you run by calling the function from your query result object:

$query = $this->db->query('SELECT * FROM some_table');

foreach ($query->list_fields() as $field)
{
   echo $field;
}

$this->db->field_exists()

Sometimes it's helpful to know whether a particular field exists before performing an action. Returns a boolean TRUE/FALSE. Usage example:

if ($this->db->field_exists('field_name', 'table_name'))
{
   // some code...
}

Note: Replace field_name with the name of the column you are looking for, and replace table_name with the name of the table you are looking for.

$this->db->field_data()

Returns an array of objects containing field information.

Sometimes it's helpful to gather the field names or other metadata, like the column type, max length, etc.

Note: Not all databases provide meta-data.

Usage example:

$fields = $this->db->field_data('table_name');

foreach ($fields as $field)
{
   echo $field->name;
   echo $field->type;
   echo $field->max_length;
   echo $field->primary_key;
}

If you have run a query already you can use the result object instead of supplying the table name:

$query = $this->db->query("YOUR QUERY");
$fields = $query->field_data();

The following data is available from this function if supported by your database:

  • name - column name
  • max_length - maximum length of the column
  • primary_key - 1 if the column is a primary key
  • type - the type of the column