How to convert CLOB type data to string in PHP

In PHP development, converting CLOB type data to string is a very common problem. CLOB, Character Large Object, is a character type provided by Oracle database. It is usually used to store longer text data, such as long articles or novels.

In Java or other programming languages, converting CLOB type data to strings is relatively simple, but in PHP, it is relatively more complicated. Therefore, in this article, we will introduce some methods to convert CLOB type data to string in PHP.

Method 1: Use the TO_LOB function provided by Oracle

If you are using an Oracle database, you can use the TO_LOB function provided by Oracle to convert CLOB type data into a string. The specific method is as follows:

// 假设clob字段为CLOB类型的数据，$db为数据库连接对象
$sql = "SELECT TO_LOB(clob) FROM tablename WHERE id = 1";
$result = oci_parse($db, $sql);
oci_execute($result);
$row = oci_fetch_array($result);

// 转换CLOB数据为字符串
$string = $row[0]->read($row[0]->size());

Method 2: Use COM object to convert CLOB to string

If you are using other types of databases and the PHP version is above 7.0, you can use COM Object converts CLOB type data into a string. The specific method is as follows:

// 假设clob字段为CLOB类型的数据，$db为数据库连接对象
$sql = "SELECT clob FROM tablename WHERE id = 1";
$result = mysqli_query($db, $sql);
$row = mysqli_fetch_array($result);

// 转换CLOB数据为字符串
$stream = $row['clob'];
$com = new COM("ADODB.Stream");
$com->Open();
$com->Write($stream);
$com->Position = 0;
$string = $com->ReadText();
$com->Close();

Method 3: Convert CLOB to string through Oracle's DBMS_LOB package

If you are using other types of databases and the PHP version is below 7.0, you can Use Oracle's DBMS_LOB package to convert CLOB type data into strings. The specific methods are as follows:

// 假设clob字段为CLOB类型的数据，$db为数据库连接对象
$sql = "SELECT clob FROM tablename WHERE id = 1";
$result = mysqli_query($db, $sql);
$row = mysqli_fetch_array($result);

// 转换CLOB数据为字符串
$lob = empty($row['clob']) ? "" : $row['clob']->load();
$handle = oci_new_descriptor($db,OCI_D_LOB);
$handle->writeTemporary($lob, OCI_TEMP_BLOB);
$string = $handle->load();
$handle->free();

The above are the three methods for converting CLOB type data into strings. In actual development, which method to use depends on the type of database you have and what the code needs to achieve. Hope this article is helpful to you.

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