PostgreSQL教程

PHP连接PostgreSQL数据库

PostgreSQL扩展在默认情况下在最新版本的PHP 5.3.x中是启用的。可以在编译时使用--without-pgsql来禁用它。仍然可以使用yum命令来安装PHP-PostgreSQL接口：

yum install php-pgsql

在开始使用PHP连接PostgreSQL接口之前，请先在PostgreSQL安装目录中找到pg_hba.conf文件，并添加以下行：

# IPv4 local connections:
host    all         all         127.0.0.1/32          md5

您可以启动/重新启动postgres服务器，使用以下命令运行：

[root@host]# service postgresql restart
Stopping postgresql service:                               [  OK  ]
Starting postgresql service:                               [  OK  ]

Windows用户必须启用php_pgsql.dll才能使用此扩展名。这个DLL包含在最新版本的PHP 5.3.x中的Windows发行版中。

PHP连接到PostgreSQL数据库

以下PHP代码显示如何连接到本地机器上的现有数据库，最后将返回数据库连接对象。

<?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，让我们运行上面的程序打开数据库:testdb，如果成功打开数据库连接，那么它将给出以下消息：

Opened database successfully

创建表

以下PHP程序将用于在之前创建的数据库(testdb)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);
?>

当执行上述程序时，它将在testdb数据库中创建COMPANY表，并显示以下消息：

Opened database successfully
Table created successfully

插入操作

以下PHP程序显示了如何在上述示例中创建的COMPANY表中创建记录：

<?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);
?>

当执行上述程序时，它将在COMPANY表中创建给定的记录，并显示以下两行：

Opened database successfully
Records created successfully

SELECT操作

以下PHP程序显示了如何从上述示例中创建的COMPANY表中获取和显示记录：

<?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);
?>

当执行上述程序时，将产生以下结果。请记下，在创建表时按照它们使用的顺序返回字段。

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

更新操作

以下PHP代码显示了如何使用UPDATE语句来更新指定记录，然后从COMPANY表中获取并显示更新的记录：

<?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);
?>

执行上述程序时，会产生以下结果：

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

删除操作

以下PHP代码显示了如何使用DELETE语句删除指定记录，然后从COMPANY表中获取并显示剩余的记录：

<?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
      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);
?>

执行上述程序时，会产生以下结果：

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

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