(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
pg_field_size — 返回指定字段的内部存储大小
pg_field_size() 返回给定 PostgreSQL result 中指定字段号的内部存储大小（以字节为单位）。
注意:
此函数以前称为 pg_fieldsize()。
result一个 PgSql\Result 实例，由 pg_query()、pg_query_params() 或 pg_execute()（以及其他）返回。
field字段号，从 0 开始。
内部字段存储大小（以字节为单位）。-1 表示可变长度字段。
| 版本 | 描述 |
|---|---|
| 8.1.0 | result 参数现在期望一个 PgSql\Result 实例；以前，它期望一个 资源。 |
示例 #1 获取有关字段的信息
<?php
$dbconn = pg_connect("dbname=publisher") or die("Could not connect");
$res = pg_query($dbconn, "select * from authors where author = 'Orwell'");
$i = pg_num_fields($res);
for ($j = 0; $j < $i; $j++) {
echo "column $j\n";
$fieldname = pg_field_name($res, $j);
echo "fieldname: $fieldname\n";
echo "printed length: " . pg_field_prtlen($res, $fieldname) . " characters\n";
echo "storage length: " . pg_field_size($res, $j) . " bytes\n";
echo "field type: " . pg_field_type($res, $j) . " \n\n";
}
?>上面的示例将输出
column 0 fieldname: author printed length: 6 characters storage length: -1 bytes field type: varchar column 1 fieldname: year printed length: 4 characters storage length: 2 bytes field type: int2 column 2 fieldname: title printed length: 24 characters storage length: -1 bytes field type: varchar
要使用 SQL 查询查看表的结构
select pg_class.relname, pg_attribute.attname, pg_type.typname, pg_type.typlen from pg_class, pg_attribute, pg_type where pg_class.relname = 'YOURTABLENAME' and pg_class.oid = pg_attribute.attrelid and pg_type.oid = pg_attribute.atttypid having attnum > 0函数 get_create_syntax( $table )
{
$qry = "
SELECT *
FROM $table
LIMIT 1
";
$res = pg_query( $qry );
$row = pg_fetch_assoc( $res );
$create = "CREATE TABLE $table \n(\n";
$item = array();
for( $i = 0; $i < count( $row ); $i++ )
{
$name = pg_field_name( $res, $i );
$type = pg_field_type( $res, $i );
$size = pg_field_size( $res, $i );
$item[$i] = '"'.$name.'" '.$type;
$qry = "
SELECT a.atttypmod AS size,
a.attnotnull AS notnull
FROM pg_attribute AS a,
pg_class AS c
WHERE c.relname = '$table'
AND a.attrelid = c.oid
AND a.attname = '$name'
";
$res2 = pg_query( $qry );
$out = pg_fetch_object( $res2 );
if( $out -> size != -1 )
{
$item[$i] .= '('.( $out -> size - 4 ).')';
}
if( $out -> notnull == 't' )
$item[$i] .= ' NOT';
$item[$i] .= ' NULL';
}
$create .= implode( ",\n", $item ) ."\n);";
return $create;
}如何提取 PostgreSQL 表的结构？
我想编写一段动态的 PHP 代码，它可以查看 PostgreSQL 表并打印字段的名称、类型和大小。