# fbsql_read_blob

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

fbsql_read_blob — Read a BLOB from the database

### 说明

fbsql_read_blob ( string `$blob_handle` [, resource `$link_identifier` ] ) : string

Reads BLOB data from the database.

If a select statement contains BLOB and/or CLOB columns FrontBase will return the data directly when data is fetched. This default behavior can be changed with fbsql_set_lob_mode() so the fetch functions will return handles to BLOB and CLOB data. If a handle is fetched a user must call fbsql_read_blob() to get the actual BLOB data from the database.

### 参数

`blob_handle`

  A BLOB handle, returned by fbsql_create_blob().

`link_identifier`

  由 fbsql_connect() 或 fbsql_pconnect() 返回的 FrontBase 链接标识符.

  如可选并未指定，函数会尝试查找一个到 FrontBase 服务器的开放链接，且如没有找到这样的链接，会尝试通过不带参数调用 fbsql_connect() 来创建一个。

### 返回值

Returns a string containing the specified BLOB data.

### 范例

Example #1 fbsql_read_blob() example

    <?php
    $link = fbsql_pconnect("localhost", "_SYSTEM", "secret")
        or die("Could not connect");
    $sql = "SELECT BLOB_COLUMN FROM BLOB_TABLE;";
    $rs = fbsql_query($sql, $link);
    $row_data = fbsql_fetch_row($rs);
    // $row_data[0] will now contain the blob data for the first row
    fbsql_free_result($rs);

    $rs = fbsql_query($sql, $link);
    fbsql_set_lob_mode($rs, FBSQL_LOB_HANDLE);
    $row_data = fbsql_fetch_row($rs);
    // $row_data[0] will now contain a handle to the BLOB data in the first row
    $blob_data = fbsql_read_blob($row_data[0]);
    fbsql_free_result($rs);

    ?>

### 参见

- fbsql_create_blob() - Create a BLOB
- fbsql_read_clob() - Read a CLOB from the database
- fbsql_set_lob_mode() - Set the LOB retrieve mode for a FrontBase result set