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# CXVIII. SQLite Functions

# 介紹

This is an extension for the SQLite Embeddable SQL Database Engine. SQLite is a C library that implements an embeddable SQL database engine. Programs that link with the SQLite library can have SQL database access without running a separate RDBMS process.

SQLite is not a client library used to connect to a big database server. SQLite is the server. The SQLite library reads and writes directly to and from the database files on disk.

> 注: For further information see the SQLite Website (http://sqlite.org/).

# Installation

Read the INSTALL file, which comes with the package. Or just use the PEAR installer with "pear install sqlite". SQLite itself is already included, You do not need to install any additional software.

Windows users may download the DLL version of the SQLite extension here: (php_sqlite.dll).

In PHP 5, the SQLite extension and the engine itself are bundled and compiled by default.

> Windows installation for unprivileged accounts: On Windows operating systems, unprivileged accounts don't have the TMP environment variable set by default. This will make sqlite create temporary files in the windows directory, which is not desirable. So, you should set the TMP environment variable for the web server or the user account the web server is running under. If Apache is your web server, you can accomplish this via a SetEnv directive in your `httpd.conf` file. For example:

>     SetEnv TMP c:/temp

> If you are unable to establish this setting at the server level, you can implement the setting in your script:

> `putenv('TMP=C:/temp');`

> The setting must refer to a directory that the web server has permission to create files in and subsequently write to and delete the files it created. Otherwise, you may receive the following error message: `malformed database schema - unable to open a temporary database file for storing temporary tables`

# 需求

In order to have these functions available, you must compile PHP with SQLite support, or load the SQLite extension dynamically from your `php.ini`.

# 資源類型

There are two resources used in the SQLite Interface. The first one is the database connection, the second one the result set.

# Predefined Constants

The functions sqlite_fetch_array() and sqlite_current() use a constant for the different types of result arrays. The following constants are defined:

表格 1. SQLite fetch constants

constant | meaning
--- | ---
SQLITE_ASSOC | Columns are returned into the array having the fieldname as the array index.
SQLITE_BOTH | Columns are returned into the array having both a numerical index and the fieldname as the array index.
SQLITE_NUM | Columns are returned into the array having a numerical index to the fields. This index starts with 0, the first field in the result.

# 預先定義類別

## SQLiteDatabase

Represents an opened SQLite database.

### Constructor

- __construct - construct a new SQLiteDatabase object

### Methods

- query - Execute a query

- queryExec - Execute a result-less query

- arrayQuery - Execute a query and return the result as an array

- singleQuery - Execute a query and return either an array for one single column or the value of the first row

- unbufferedQuery - Execute an unbuffered query

- lastInsertRowid - Returns the rowid of the most recently inserted row

- changes - Returns the number of rows changed by the most recent statement

- createAggregate - Register an aggregating UDF for use in SQL statements

- createFunction - Register a UDF for use in SQL statements

- busyTimeout - Sets or disables busy timeout duration

- lastErorr - Returns the last error code of the most recently encountered error

- fetchColumnTypes - Return an array of column types from a particular table

## SQLiteResult

Represents a buffered SQLite result set.

### Methods

- fetch - Fetches the next row from the result set as an array

- fetchObject - Fetches the next row from the result set as an object

- fetchSingle - Fetches the first column from the result set as a string

- fetchAll - Fetches all rows from the result set as an array of arrays

- column - Fetches a column from the current row of the result set

- numFields - Returns the number of fields in the result set

- fieldName - Returns the name of a particular field in the result set

- current - Fetches the current row from the result set as an array

- key - Return the current row index

- next - Seek to the next row number

- valid - Returns whether more rows are available

- rewind - Seek to the first row number of the result set

- prev - Seek to the previous row number of the result set

- hasPrev - Returns whether or not a previous row is available

- numRows - Returns the number of rows in the result set

- seek - Seek to a particular row number

## SQLiteUnbuffered

Represents an unbuffered SQLite result set. Unbuffered results sets are sequential, forward-seeking only.

### Methods

- fetch - Fetches the next row from the result set as an array

- fetchObject - Fetches the next row from the result set as an object

- fetchSingle - Fetches the first column from the result set as a string

- fetchAll - Fetches all rows from the result set as an array of arrays

- column - Fetches a column from the current row of the result set

- numFields - Returns the number of fields in the result set

- fieldName - Returns the name of a particular field in the result set

- current - Fetches the current row from the result set as an array

- next - Seek to the next row number

- valid - Returns whether more rows are available

# 執行時期組態

`php.ini`中的設定會影響這些函數的行為。

表格 2. SQLite Configuration Options

Name | Default | Changeable
--- | --- | ---
sqlite.assoc_case | 0 | PHP_INI_ALL

For further details and definitions of the PHP_INI_* constants, see the 附錄 H.

這裡為簡短的結構指令說明。

sqlite.assoc_case int

  Whether to use mixed case (0), upper case (1) or lower case (2) hash indexes.

  This option is primarily useful when you need compatibility with other database systems, where the names of the columns are always returned as uppercase or lowercase, regardless of the case of the actual field names in the database schema.

  The SQLite library returns the column names in their natural case (that matches the case you used in your schema). When sqlite.assoc_case is set to 0 the natural case will be preserved. When it is set to 1 or 2, PHP will apply case folding on the hash keys to upper- or lower-case the keys, respectively.

  Use of this option incurs a slight performance penalty, but is MUCH faster than performing the case folding yourself using PHP script.

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