DB Driver Reference

This is the platform-independent base DB implementation class. This class will not be called directly. Rather, the adapter class for the specific database will extend and instantiate it.

The how-to material for this has been split over several articles. This article is intended to be a reference for them.

Important

Not all methods are supported by all database drivers, some of them may fail (and return FALSE) if the underlying driver does not support them.

class CI_DB_driver
initialize()
Return type

void

Throws

RuntimeException In case of failure

Initialize database settings, establish a connection to the database.

db_connect($persistent = TRUE)
Parameters
  • $persistent (bool) – Whether to establish a persistent connection or a regular one

Returns

Database connection resource/object or FALSE on failure

Return type

mixed

Establish a connection with the database.

Note

The returned value depends on the underlying driver in use. For example, a mysqli instance will be returned with the ‘mysqli’ driver.

db_pconnect()
Returns

Database connection resource/object or FALSE on failure

Return type

mixed

Establish a persistent connection with the database.

Note

This method is just an alias for db_connect(TRUE).

reconnect()
Returns

TRUE on success, FALSE on failure

Return type

bool

Keep / reestablish the database connection if no queries have been sent for a length of time exceeding the server’s idle timeout.

db_select([$database = ''])
Parameters
  • $database (string) – Database name

Returns

TRUE on success, FALSE on failure

Return type

bool

Select / switch the current database.

platform()
Returns

Platform name

Return type

string

The name of the platform in use (mysql, mssql, etc…).

version()
Returns

The version of the database being used

Return type

string

Database version number.

query($sql[, $binds = FALSE[, $return_object = NULL]])
Parameters
  • $sql (string) – The SQL statement to execute

  • $binds (array) – An array of binding data

  • $return_object (bool) – Whether to return a result object or not

Returns

TRUE for successful “write-type” queries, CI_DB_result instance (method chaining) on “query” success, FALSE on failure

Return type

mixed

Execute an SQL query.

Accepts an SQL string as input and returns a result object upon successful execution of a “read” type query.

Returns:

  • Boolean TRUE upon successful execution of a “write type” queries

  • Boolean FALSE upon failure

  • CI_DB_result object for “read type” queries

simple_query($sql)
Parameters
  • $sql (string) – The SQL statement to execute

Returns

Whatever the underlying driver’s “query” function returns

Return type

mixed

A simplified version of the query() method, appropriate for use when you don’t need to get a result object or to just send a query to the database and not care for the result.

affected_rows()
Returns

Number of rows affected

Return type

int

Returns the number of rows changed by the last executed query.

Useful for checking how much rows were created, updated or deleted during the last executed query.

trans_strict([$mode = TRUE])
Parameters
  • $mode (bool) – Strict mode flag

Return type

void

Enable/disable transaction “strict” mode.

When strict mode is enabled, if you are running multiple groups of transactions and one group fails, all subsequent groups will be rolled back.

If strict mode is disabled, each group is treated autonomously, meaning a failure of one group will not affect any others.

trans_off()
Return type

void

Disables transactions at run-time.

trans_start([$test_mode = FALSE])
Parameters
  • $test_mode (bool) – Test mode flag

Returns

TRUE on success, FALSE on failure

Return type

bool

Start a transaction.

trans_complete()
Returns

TRUE on success, FALSE on failure

Return type

bool

Complete Transaction.

trans_status()
Returns

TRUE if the transaction succeeded, FALSE if it failed

Return type

bool

Lets you retrieve the transaction status flag to determine if it has failed.

trans_active()
Returns

TRUE if a transaction is active, FALSE if not

Return type

bool

Determines if a transaction is currently active.

compile_binds($sql, $binds)
Parameters
  • $sql (string) – The SQL statement

  • $binds (array) – An array of binding data

Returns

The updated SQL statement

Return type

string

Compiles an SQL query with the bind values passed for it.

is_write_type($sql)
Parameters
  • $sql (string) – The SQL statement

Returns

TRUE if the SQL statement is of “write type”, FALSE if not

Return type

bool

Determines if a query is of a “write” type (such as INSERT, UPDATE, DELETE) or “read” type (i.e. SELECT).

elapsed_time([$decimals = 6])
Parameters
  • $decimals (int) – The number of decimal places

Returns

The aggregate query elapsed time, in microseconds

Return type

string

Calculate the aggregate query elapsed time.

total_queries()
Returns

The total number of queries executed

Return type

int

Returns the total number of queries that have been executed so far.

last_query()
Returns

The last query executed

Return type

string

Returns the last query that was executed.

escape($str)
Parameters
  • $str (mixed) – The value to escape, or an array of multiple ones

Returns

The escaped value(s)

Return type

mixed

Escapes input data based on type, including boolean and NULLs.

escape_str($str[, $like = FALSE])
Parameters
  • $str (mixed) – A string value or array of multiple ones

  • $like (bool) – Whether or not the string will be used in a LIKE condition

Returns

The escaped string(s)

Return type

mixed

Escapes string values.

Warning

The returned strings do NOT include quotes around them.

escape_like_str($str)
Parameters
  • $str (mixed) – A string value or array of multiple ones

Returns

The escaped string(s)

Return type

mixed

Escape LIKE strings.

Similar to escape_str(), but will also escape the % and _ wildcard characters, so that they don’t cause false-positives in LIKE conditions.

Important

The escape_like_str() method uses ‘!’ (exclamation mark) to escape special characters for LIKE conditions. Because this method escapes partial strings that you would wrap in quotes yourself, it cannot automatically add the ESCAPE '!' condition for you, and so you’ll have to manually do that.

primary($table)
Parameters
  • $table (string) – Table name

Returns

The primary key name, FALSE if none

Return type

string

Retrieves the primary key of a table.

Note

If the database platform does not support primary key detection, the first column name may be assumed as the primary key.

count_all([$table = ''])
Parameters
  • $table (string) – Table name

Returns

Row count for the specified table

Return type

int

Returns the total number of rows in a table, or 0 if no table was provided.

list_tables([$constrain_by_prefix = FALSE])
Parameters
  • $constrain_by_prefix (bool) – TRUE to match table names by the configured dbprefix

Returns

Array of table names or FALSE on failure

Return type

array

Gets a list of the tables in the current database.

table_exists($table_name)
Parameters
  • $table_name (string) – The table name

Returns

TRUE if that table exists, FALSE if not

Return type

bool

Determine if a particular table exists.

list_fields($table)
Parameters
  • $table (string) – The table name

Returns

Array of field names or FALSE on failure

Return type

array

Gets a list of the field names in a table.

field_exists($field_name, $table_name)
Parameters
  • $table_name (string) – The table name

  • $field_name (string) – The field name

Returns

TRUE if that field exists in that table, FALSE if not

Return type

bool

Determine if a particular field exists.

field_data($table)
Parameters
  • $table (string) – The table name

Returns

Array of field data items or FALSE on failure

Return type

array

Gets a list containing field data about a table.

escape_identifiers($item, $split = TRUE)
Parameters
  • $item (mixed) – The item or array of items to escape

  • $split (bool) – Whether to split identifiers when a dot is encountered

Returns

The input item(s), escaped

Return type

mixed

Escape SQL identifiers, such as column, table and names.

insert_string($table, $data)
Parameters
  • $table (string) – The target table

  • $data (array) – An associative array of key/value pairs

Returns

The SQL INSERT statement, as a string

Return type

string

Generate an INSERT statement string.

update_string($table, $data, $where)
Parameters
  • $table (string) – The target table

  • $data (array) – An associative array of key/value pairs

  • $where (mixed) – The WHERE statement conditions

Returns

The SQL UPDATE statement, as a string

Return type

string

Generate an UPDATE statement string.

call_function($function)
Parameters
  • $function (string) – Function name

Returns

The function result

Return type

string

Runs a native PHP function , using a platform agnostic wrapper.

cache_set_path([$path = ''])
Parameters
  • $path (string) – Path to the cache directory

Return type

void

Sets the directory path to use for caching storage.

cache_on()
Returns

TRUE if caching is on, FALSE if not

Return type

bool

Enable database results caching.

cache_off()
Returns

TRUE if caching is on, FALSE if not

Return type

bool

Disable database results caching.

cache_delete([$segment_one = ''[, $segment_two = '']])
Parameters
  • $segment_one (string) – First URI segment

  • $segment_two (string) – Second URI segment

Returns

TRUE on success, FALSE on failure

Return type

bool

Delete the cache files associated with a particular URI.

cache_delete_all()
Returns

TRUE on success, FALSE on failure

Return type

bool

Delete all cache files.

close()
Return type

void

Close the DB Connection.

display_error([$error = ''[, $swap = ''[, $native = FALSE]]])
Parameters
  • $error (string) – The error message

  • $swap (string) – Any “swap” values

  • $native (bool) – Whether to localize the message

Return type

void

Returns

Displays the DB error screensends the application/views/errors/error_db.php template

Return type

string

Display an error message and stop script execution.

The message is displayed using the application/views/errors/error_db.php template.

protect_identifiers($item[, $prefix_single = FALSE[, $protect_identifiers = NULL[, $field_exists = TRUE]]])
Parameters
  • $item (string) – The item to work with

  • $prefix_single (bool) – Whether to apply the dbprefix even if the input item is a single identifier

  • $protect_identifiers (bool) – Whether to quote identifiers

  • $field_exists (bool) – Whether the supplied item contains a field name or not

Returns

The modified item

Return type

string

Takes a column or table name (optionally with an alias) and applies the configured dbprefix to it.

Some logic is necessary in order to deal with column names that include the path.

Consider a query like this:

SELECT * FROM hostname.database.table.column AS c FROM hostname.database.table

Or a query with aliasing:

SELECT m.member_id, m.member_name FROM members AS m

Since the column name can include up to four segments (host, DB, table, column) or also have an alias prefix, we need to do a bit of work to figure this out and insert the table prefix (if it exists) in the proper position, and escape only the correct identifiers.

This method is used extensively by the Query Builder class.