User Guide - consolidate table & field metadata pages

Signed-off-by:James L Parry <jim_parry@bcit.ca>

1 files changed, 130 insertions, 0 deletions

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+#################
+Database Metadata
+#################
+
+**************
+Table MetaData
+**************
+
+These functions let you fetch table information.
+
+List the Tables in Your Database
+================================
+
+**$this->db->list_tables();**
+
+Returns an array containing the names of all the tables in the database
+you are currently connected to. Example::
+
+	$tables = $this->db->list_tables();
+	
+	foreach ($tables as $table)
+	{
+		echo $table;
+	}
+
+
+Determine If a Table Exists
+===========================
+
+**$this->db->table_exists();**
+
+Sometimes it's helpful to know whether a particular table exists before
+running an operation on it. Returns a boolean TRUE/FALSE. Usage example::
+
+	if ($this->db->table_exists('table_name'))
+	{
+		// some code...
+	}
+
+.. note:: Replace *table_name* with the name of the table you are looking for.
+
+
+**************
+Field MetaData
+**************
+
+List the Fields in a Table
+==========================
+
+**$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 $field;
+	}
+
+
+Determine If a Field is Present in a Table
+==========================================
+
+**$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 ($this->db->field_exists('field_name', 'table_name'))
+	{
+		// some code...
+	}
+
+.. note:: Replace *field_name* with the name of the column you are looking
+	for, and replace *table_name* with the name of the table you are
+	looking for.
+
+
+Retrieve Field Metadata
+=======================
+
+**$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