Edit Report a Bug

pg_query

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

pg_query — 执行查询

说明

pg_query(PgSql\Connection $connection = ?, string $query): PgSql\Result|false

pg_query() 在特定数据库 connection 上执行 query。pg_query_params() 在大多数情况下应该是首选。

如果发生错误并返回 false，那么在连接有效时可以使用 pg_last_error() 函数检索错误的详细信息。

注意: 尽管可以省略 connection，但不建议这样做，因为可能会导致脚本中的错误难以发现。

注意:
本函数以前的名字为 pg_exec()。pg_exec() 因为兼容性原因仍可使用，但鼓励用户使用新名称。

参数

connection

An PgSql\Connection instance. When connection is unspecified, the default connection is used. The default connection is the last connection made by pg_connect() or pg_pconnect().

警告

As of PHP 8.1.0, using the default connection is deprecated.

query

要执行的 SQL 语句。当多个语句传递给函数时，将作为一个事务自动执行，除非查询字符串中包含明确的 BEGIN/COMMIT 命令。但是，不建议在一个函数调用中使用多个事务。

警告

用户提供的数据作为字符串插入值非常危险，很可能导致 SQL 注入漏洞。在大多数情况下，应该首选 pg_query_params()，将用户提供的值作为参数传递，而不是将它们替换为查询字符串。

任何用户提供的数据，都应该正确转义，然后直接替换为查询字符串。

返回值

成功时为 PgSql\Result 实例，或者在失败时返回 false。

更新日志

版本	说明
8.1.0	现在返回 PgSql\Result 实例，之前返回 resource
8.1.0	现在 `connection` 参数接受 PgSql\Connection 实例，之前接受 resource。

示例

示例 #1 pg_query() 示例

<?php

$conn = pg_pconnect("dbname=publisher");
if (!$conn) {
  echo "An error occurred.\n";
  exit;
}

$result = pg_query($conn, "SELECT author, email FROM authors");
if (!$result) {
  echo "An error occurred.\n";
  exit;
}

while ($row = pg_fetch_row($result)) {
  echo "Author: $row[0]  E-mail: $row[1]";
  echo "<br />\n";
}

?>

示例 #2 使用多条语句的 pg_query()

<?php

$conn = pg_pconnect("dbname=publisher");

// 这些语句将作为一个事务执行

$query = "UPDATE authors SET author=UPPER(author) WHERE id=1;";
$query .= "UPDATE authors SET author=LOWER(author) WHERE id=2;";
$query .= "UPDATE authors SET author=NULL WHERE id=3;";

pg_query($conn, $query);

?>

参见

pg_connect() - 打开 PostgreSQL 连接
pg_pconnect() - 打开一个持久的 PostgreSQL 连接
pg_fetch_array() - 获取一行作为数组
pg_fetch_object() - 获取一行作为对象
pg_num_rows() - 返回结果中行的数量
pg_affected_rows() - 返回受影响的记录数（元组）

add a note

User Contributed Notes 10 notes

down

jsuzuki at spamcop dot net ¶

18 years ago


expanding on the note left by "cmoore" -

To check to see if the recordset returned no records,

<?php
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
    echo "query did not execute";
  }
  $rs = pg_fetch_assoc($result);
  if (!$rs) {
    echo "0 records"
  }
?>

-jack

down

zoli at makettinfo.hu ¶

18 years ago


It would be better this way:

<?php
  $result=pg_query($conn, "SELECT COUNT(*) AS rows FROM x WHERE a=b;");
  if  (!$result) {
   echo "query did not execute";
  }
  if ($line = pg_fetch_assoc($result)) {
    if ($line['rows'] == 0) {
     echo "0 records"
    }
  }
  else {
   while ($row = pg_fetch_array($result)) {
     //do stuff with $row
   }
  }
?> 

This solution doesn't raise the load of the system with the move of matching rows (perhaps 0,1, perhaps 100, 1000, ... rows)

down

a dot mcruer at live dot com ¶

11 years ago


A quick note for novice users: when gathering input from fields on a web form that maintains a database connection, *never* use pg_query to do queries from the field. Always sanitize input using pg_prepare and pg_execute.

down

mentat at azsoft dot pl ¶

22 years ago


$GLOBALS["PG_CONNECT"]=pg_connect(...);
....

function query ($sqlQuery,$var=0) {
   if (!$GLOBALS["PG_CONNECT"]) return 0;
   $lev=error_reporting (8); //NO WARRING!!
   $result=pg_query ($sqlQuery);
   error_reporting ($lev); //DEFAULT!!
   if (strlen ($r=pg_last_error ($GLOBALS["PG_CONNECT"]))) {
      if ($var) {
        echo "<p color=\"red\">ERROR:<pre>";
        echo $sqlQuery;
        echo "</pre>";
        echo $r;
        echo "&lt/p>";
      }
      close_db ();
      return 0;
   }
   return $result;
}

down

cmoore ¶

19 years ago


One thing to note that wasn't obvious to me at first.  If your query returns zero rows, that is not a "failed" query.  So the following is wrong:
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
    echo "No a=b in x\n";
  }

pg_query returns FALSE if the query can not be executed for some reason.  If the query is executed but returns zero rows then you get back a resul with no rows.

down

mankyd ¶

18 years ago


There was a typo in the code that I posted:

<?php
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
   echo "query did not execute";
  }
  if (pg_num_rows($result) == 0) {
   echo "0 records"
  }
  else {
   while ($row = pg_fetch_array($result)) {
     //do stuff with $row
   }
  }
?>

down

mankyd ¶

18 years ago


Improving upon what jsuzuki said:

It's probably better to use pg_num_rows() to see if no rows were returned, as that leaves the resultset cursor pointed to the first row so you can use it in a loop.

Example:

<?php
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
   echo "query did not execute";
  }
  if (pg_num_rows($result) == 0) {
   echo "0 records"
  }
  else {
    while ($row = pg_fetch_array($result) {
      //do stuff with $row
    }
  }
?>

I, personally, also find it more readable.

down

-1

Anonymous ¶

10 years ago


Here is my small function to make it easier for me to use data from select queries (attention, it is sensitive to sql injection)
<?php
function requestToDB($connection,$request){ 
    if(!$result=pg_query($connection,$request)){
        return False;
    }
    $combined=array();
    while ($row = pg_fetch_assoc($result)) {
        $combined[]=$row;
    }
    return $combined;
}
?>

Example:
<?php
$conn = pg_pconnect("dbname=mydatabase");

$results=requestToDB($connect,"select * from mytable");

//You can now access a "cell" of your table like this:
$rownumber=0;
$columname="mycolumn";

$mycell=$results[$rownumber][$columname];
var_dump($mycell);

down

-2

Akbar ¶

19 years ago


Use pg_query to call your stored procedures, and use pg_fetch_result when getting a value (like a smallint as in this example) returned by your stored procedure.

<?php
$pgConnection = pg_connect("dbname=users user=me");

$userNameToCheckFor = "metal";

$result = pg_query($pgConnection, "SELECT howManyUsersHaveThisName('$userNameToCheckFor')");

$count = pg_fetch_result($result, 0, 'howManyUsersHaveThisName');
?>

down

-8

sd at dicksonlife dot com ¶

18 years ago


Took me a while to track this down so I thought it might be useful for others:

If you use stored procedures and need to get result sets back from them:

function dbquery($link,$query){
  pg_query($link,"BEGIN;");
  $tr=pg_query($link,$query);
  $r=pg_fetch_row($tr);
  $name=$r[0];
  $rs=pg_query($link,"FETCH ALL IN \"" . $name . "\";");
  pg_query($link,"END;");
  return $rs;
}

(Error checking removed for clarity)

add a note