# db2_lob_read

(PECL ibm_db2 >= 1.6.0)

db2_lob_read — Gets a user defined size of LOB files with each invocation

### 说明

db2_lob_read ( resource `$stmt` , int `$colnum` , int `$length` ) : string

Use db2_lob_read() to iterate through a specified column of a result set and retrieve a user defined size of LOB data.

### 参数

`stmt`

  A valid stmt resource containing LOB data.

`colnum`

  A valid column number in the result set of the stmt resource.

`length`

  The size of the LOB data to be retrieved from the stmt resource.

### 返回值

Returns the amount of data the user specifies. Returns `FALSE` if the data cannot be retrieved.

### 范例

Example #1 Iterating through different types of data

    <?php

    /* Database Connection Parameters */
    $db = 'SAMPLE';
    $username = 'db2inst1';
    $password = 'ibmdb2';

    /* Obtain Connection Resource */
    $conn = db2_connect($db,$username,$password);

    if ($conn) {
        $drop = 'DROP TABLE clob_stream';
        $result = @db2_exec( $conn, $drop );

        $create = 'CREATE TABLE clob_stream (id INTEGER, my_clob CLOB)';
        $result = db2_exec( $conn, $create );

        $variable = "";
        $stmt = db2_prepare($conn, "INSERT INTO clob_stream (id,my_clob) VALUES (1, ?)");
        $variable = "THIS IS A CLOB TEST. THIS IS A CLOB TEST.";
        db2_bind_param($stmt, 1, "variable", DB2_PARAM_IN);
        db2_execute($stmt);

        $sql = "SELECT id,my_clob FROM clob_stream";
        $result = db2_prepare($conn, $sql);
        db2_execute($result);
        db2_fetch_row($result);
        $i = 0;
        /* Read LOB data */
        while ($data = db2_lob_read($result, 2, 6)) {
            echo "Loop $i: $data\n";
            $i = $i + 1;
        }

        $drop = 'DROP TABLE blob_stream';
        $result = @db2_exec( $conn, $drop );

        $create = 'CREATE TABLE blob_stream (id INTEGER, my_blob CLOB)';
        $result = db2_exec( $conn, $create );

        $variable = "";
        $stmt = db2_prepare($conn, "INSERT INTO blob_stream (id,my_blob) VALUES (1, ?)");
        $variable = "THIS IS A BLOB TEST. THIS IS A BLOB TEST.";
        db2_bind_param($stmt, 1, "variable", DB2_PARAM_IN);
        db2_execute($stmt);

        $sql = "SELECT id,my_blob FROM blob_stream";
        $result = db2_prepare($conn, $sql);
        db2_execute($result);
        db2_fetch_row($result);
        $i = 0;
        /* Read LOB data */
        while ($data = db2_lob_read($result, 2, 6)) {
            echo "Loop $i: $data\n";
            $i = $i + 1;
        }
    } else {
        echo 'no connection: ' . db2_conn_errormsg();
    }

    ?>

以上例程会输出：

    Loop 0: THIS I
    Loop 1: S A CL
    Loop 2: OB TES
    Loop 3: T. THI
    Loop 4: S IS A
    Loop 5:  CLOB
    Loop 6: TEST.
    Loop 0: THIS I
    Loop 1: S A BL
    Loop 2: OB TES
    Loop 3: T. THI
    Loop 4: S IS A
    Loop 5:  BLOB
    Loop 6: TEST.

### 参见

- db2_bind_param() - Binds a PHP variable to an SQL statement parameter
- db2_exec() - Executes an SQL statement directly
- db2_execute() - Executes a prepared SQL statement
- db2_fetch_row() - Sets the result set pointer to the next row or requested row
- db2_prepare() - Prepares an SQL statement to be executed
- db2_result() - Returns a single column from a row in the result set