Postgresql 简明教程
PostgreSQL - PHP Interface
Installation
在 PHP 5.3.x 的最新版本中,PostgreSQL 扩展默认情况下启用。可以通过在编译时使用 --without-pgsql 禁用它。不过您仍然可以使用 yum 命令安装 PHP -PostgreSQL 接口:
yum install php-pgsql
在开始使用 PHP PostgreSQL 接口之前,在您的 PostgreSQL 安装目录中找到 pg_hba.conf 文件,添加以下行:
# IPv4 local connections:
host all all 127.0.0.1/32 md5
如果 postgres 服务未运行,可以使用以下命令启动/重新启动它:
[root@host]# service postgresql restart
Stopping postgresql service: [ OK ]
Starting postgresql service: [ OK ]
Windows 用户必须启用 php_pgsql.dll 才能使用此扩展。此 DLL 在 PHP 5.3.x 的最新版本中包含在 Windows 发行版中。
有关详细的安装说明,请查看 PHP 教程及其官方网站。
PHP Interface APIs
以下几个重要的 PHP 例程可以满足您使用 PHP 程序操作 PostgreSQL 数据库的需求。如果您正在寻找更为复杂成熟的应用程序,则可以查看 PHP 官方文档。
S. No. |
API & Description |
1 |
resource pg_connect ( string $connection_string [, int $connect_type ] ) 打开一个到 PostgreSQL 数据库的连接,该数据库通过 connection_string 指定。如果 PGSQL_CONNECT_FORCE_NEW 传递为 connect_type,那么在第二次调用 pg_connect() 时将创建一个新连接,即使 connection_string 与现有连接相同。 |
2 |
bool pg_connection_reset ( resource $connection ) 此例程重置连接。对于错误恢复而言,它是非常有用的。如果成功,则返回 TRUE,如果失败,则返回 FALSE。 |
3 |
int pg_connection_status ( resource $connection ) 此例程返回指定连接的状态。返回 PGSQL_CONNECTION_OK 或 PGSQL_CONNECTION_BAD。 |
4 |
string pg_dbname ([ resource $connection ] ) 此例程返回指定 PostgreSQL 连接资源所属数据库的名称。 |
5 |
resource pg_prepare ([ resource $connection ], string $stmtname, string $query ) 此例程提交一个请求,使用指定参数创建已准备好的语句,并且等待完成。 |
6 |
resource pg_execute ([ resource $connection ], string $stmtname, array $params ) 此例程发送一个请求,使用指定参数执行已准备好的语句,并且等待结果。 |
7 |
resource pg_query ([ resource $connection ], string $query ) 此例程对指定数据库连接执行查询。 |
8 |
array pg_fetch_row ( resource $result [, int $row ] ) 此例程从与指定结果资源相关联的结果中获取一行数据。 |
9 |
array pg_fetch_all ( resource $result ) 此例程返回一个包含结果资源中所有行(记录)的数组。 |
10 |
int pg_affected_rows ( resource $result ) 此例程返回 INSERT、UPDATE 和 DELETE 查询影响的行数。 |
11 |
int pg_num_rows ( resource $result ) 此例程返回 PostgreSQL 结果资源中的行数,例如 SELECT 语句返回的行数。 |
12 |
bool pg_close ([ resource $connection ] ) 此例程关闭与指定连接资源相关联的 PostgreSQL 数据库的非持久连接。 |
13 |
string pg_last_error ([ resource $connection ] ) 此例程返回指定连接的最后一个错误消息。 |
14 |
string pg_escape_literal ([ resource $connection ], string $data ) 此例程为插入文本字段转义文字。 |
15 |
string pg_escape_string ([ resource $connection ], string $data ) 此例程为查询数据库转义字符串。 |
Connecting to Database
以下 PHP 代码展示了如何连接到本地计算机上的现有数据库,最后将返回一个数据库连接对象。
<?php
$host = "host = 127.0.0.1";
$port = "port = 5432";
$dbname = "dbname = testdb";
$credentials = "user = postgres password=pass123";
$db = pg_connect( "$host $port $dbname $credentials" );
if(!$db) {
echo "Error : Unable to open database\n";
} else {
echo "Opened database successfully\n";
}
?>
现在,让我们运行以上提供的程序打开我们的数据库 testdb :如果数据库打开成功,那么它将给出以下消息 −
Opened database successfully
Create a Table
以下 PHP 程序将用于在之前创建的数据库中创建一个表 −
<?php
$host = "host = 127.0.0.1";
$port = "port = 5432";
$dbname = "dbname = testdb";
$credentials = "user = postgres password=pass123";
$db = pg_connect( "$host $port $dbname $credentials" );
if(!$db) {
echo "Error : Unable to open database\n";
} else {
echo "Opened database successfully\n";
}
$sql =<<<EOF
CREATE TABLE COMPANY
(ID INT PRIMARY KEY NOT NULL,
NAME TEXT NOT NULL,
AGE INT NOT NULL,
ADDRESS CHAR(50),
SALARY REAL);
EOF;
$ret = pg_query($db, $sql);
if(!$ret) {
echo pg_last_error($db);
} else {
echo "Table created successfully\n";
}
pg_close($db);
?>
当执行给定上面的程序时,它将在您的 testdb 中创建 COMPANY 表,然后显示以下消息 −
Opened database successfully
Table created successfully
INSERT Operation
以下 PHP 程序展示了如何在上述实例中创建的 COMPANY 表内创建记录 −
<?php
$host = "host=127.0.0.1";
$port = "port=5432";
$dbname = "dbname = testdb";
$credentials = "user = postgres password=pass123";
$db = pg_connect( "$host $port $dbname $credentials" );
if(!$db) {
echo "Error : Unable to open database\n";
} else {
echo "Opened database successfully\n";
}
$sql =<<<EOF
INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (1, 'Paul', 32, 'California', 20000.00 );
INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (2, 'Allen', 25, 'Texas', 15000.00 );
INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (3, 'Teddy', 23, 'Norway', 20000.00 );
INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (4, 'Mark', 25, 'Rich-Mond ', 65000.00 );
EOF;
$ret = pg_query($db, $sql);
if(!$ret) {
echo pg_last_error($db);
} else {
echo "Records created successfully\n";
}
pg_close($db);
?>
当执行上述提供的程序时,它将在 COMPANY 表中创建给定的记录,并且显示以下两行 −
Opened database successfully
Records created successfully
SELECT Operation
以下 PHP 程序展示了如何从上述示例中创建的 COMPANY 表中获取并显示记录 -
<?php
$host = "host = 127.0.0.1";
$port = "port = 5432";
$dbname = "dbname = testdb";
$credentials = "user = postgres password=pass123";
$db = pg_connect( "$host $port $dbname $credentials" );
if(!$db) {
echo "Error : Unable to open database\n";
} else {
echo "Opened database successfully\n";
}
$sql =<<<EOF
SELECT * from COMPANY;
EOF;
$ret = pg_query($db, $sql);
if(!$ret) {
echo pg_last_error($db);
exit;
}
while($row = pg_fetch_row($ret)) {
echo "ID = ". $row[0] . "\n";
echo "NAME = ". $row[1] ."\n";
echo "ADDRESS = ". $row[2] ."\n";
echo "SALARY = ".$row[4] ."\n\n";
}
echo "Operation done successfully\n";
pg_close($db);
?>
执行上述程序后,将生成以下结果。请注意,字段以在创建表时使用的顺序返回。
Opened database successfully
ID = 1
NAME = Paul
ADDRESS = California
SALARY = 20000
ID = 2
NAME = Allen
ADDRESS = Texas
SALARY = 15000
ID = 3
NAME = Teddy
ADDRESS = Norway
SALARY = 20000
ID = 4
NAME = Mark
ADDRESS = Rich-Mond
SALARY = 65000
Operation done successfully
UPDATE Operation
以下 PHP 代码展示了如何使用 UPDATE 语句更新任何记录,然后从 COMPANY 表中获取并显示更新后的记录 -
<?php
$host = "host=127.0.0.1";
$port = "port=5432";
$dbname = "dbname = testdb";
$credentials = "user = postgres password=pass123";
$db = pg_connect( "$host $port $dbname $credentials" );
if(!$db) {
echo "Error : Unable to open database\n";
} else {
echo "Opened database successfully\n";
}
$sql =<<<EOF
UPDATE COMPANY set SALARY = 25000.00 where ID=1;
EOF;
$ret = pg_query($db, $sql);
if(!$ret) {
echo pg_last_error($db);
exit;
} else {
echo "Record updated successfully\n";
}
$sql =<<<EOF
SELECT * from COMPANY;
EOF;
$ret = pg_query($db, $sql);
if(!$ret) {
echo pg_last_error($db);
exit;
}
while($row = pg_fetch_row($ret)) {
echo "ID = ". $row[0] . "\n";
echo "NAME = ". $row[1] ."\n";
echo "ADDRESS = ". $row[2] ."\n";
echo "SALARY = ".$row[4] ."\n\n";
}
echo "Operation done successfully\n";
pg_close($db);
?>
当执行给定上面的程序时,它将产生以下结果 −
Opened database successfully
Record updated successfully
ID = 2
NAME = Allen
ADDRESS = 25
SALARY = 15000
ID = 3
NAME = Teddy
ADDRESS = 23
SALARY = 20000
ID = 4
NAME = Mark
ADDRESS = 25
SALARY = 65000
ID = 1
NAME = Paul
ADDRESS = 32
SALARY = 25000
Operation done successfully
DELETE Operation
以下 PHP 代码展示了如何使用 DELETE 语句删除任何记录,然后从 COMPANY 表中获取并显示其余记录 -
<?php
$host = "host = 127.0.0.1";
$port = "port = 5432";
$dbname = "dbname = testdb";
$credentials = "user = postgres password=pass123";
$db = pg_connect( "$host $port $dbname $credentials" );
if(!$db) {
echo "Error : Unable to open database\n";
} else {
echo "Opened database successfully\n";
}
$sql =<<<EOF
DELETE from COMPANY where ID=2;
EOF;
$ret = pg_query($db, $sql);
if(!$ret) {
echo pg_last_error($db);
exit;
} else {
echo "Record deleted successfully\n";
}
$sql =<<<EOF
SELECT * from COMPANY;
EOF;
$ret = pg_query($db, $sql);
if(!$ret) {
echo pg_last_error($db);
exit;
}
while($row = pg_fetch_row($ret)) {
echo "ID = ". $row[0] . "\n";
echo "NAME = ". $row[1] ."\n";
echo "ADDRESS = ". $row[2] ."\n";
echo "SALARY = ".$row[4] ."\n\n";
}
echo "Operation done successfully\n";
pg_close($db);
?>
当执行给定上面的程序时,它将产生以下结果 −
Opened database successfully
Record deleted successfully
ID = 3
NAME = Teddy
ADDRESS = 23
SALARY = 20000
ID = 4
NAME = Mark
ADDRESS = 25
SALARY = 65000
ID = 1
NAME = Paul
ADDRESS = 32
SALARY = 25000
Operation done successfully