blob/bfile
通常在前端使用二進制流來讀寫的。
通常在前端使用二進制流來讀寫的。
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REM Version 1.0, last updated 8/8/97
REM This file demonstrates some DML operations on internal LOBs, as described
REM in Chapter 21 of _Oracle8 PL/SQL Programming_ by Scott Urman.DECLARE
v_CLOBlocator CLOB;
v_BLOBlocator BLOB;
BEGIN
-- Initializes the clob_col to the specified string, and returns the
-- locator into v_LOBlocator.
INSERT INTO lobdemo (key, clob_col)
VALUES (20, 'abcdefghijklmnopqrstuvwxyz')
RETURNING clob_col INTO v_CLOBlocator; -- Modifies blob_col for the same row.
UPDATE lobdemo
SET blob_col = HEXTORAW('00FF00FF00FF')
WHERE key = 20; -- Retrieves the locator for the newly updated value, not the value
-- itself.
SELECT blob_col
INTO v_BLOBlocator
FROM lobdemo
WHERE key = 20;
END;
/
REM Version 1.0, last updated 8/8/97
REM This procedure demonstrates many DBMS_LOB routines, including the BFILE
REM manipulation routines, as described in Chapter 21 of
REM _Oracle8 PL/SQL Programming_ by Scott Urman.CREATE OR REPLACE PROCEDURE FileExec(
-- Executes the SQL statements in the file identified by
-- p_Directory and p_FileName. Each statement should not contain
-- the trailing semicolon (unless it is a PL/SQL block) and should
-- be separated by p_SeparationChar.
p_Directory IN VARCHAR2,
p_FileName IN VARCHAR2,
p_SeparationChar IN CHAR) AS v_FileLocator BFILE;
v_CLOBLocator CLOB;
v_SQLCursor INTEGER;
v_StartPoint INTEGER := 1;
v_EndPoint INTEGER;
v_SQLStatement VARCHAR2(32000);
v_StatementLength INTEGER;
v_RC INTEGER;
BEGIN
-- Initialize the character locator for writing. Note that we have
-- to select a CLOB from a table FOR UPDATE. This locks the row,
-- and is a requirement for LOADFROMFILE.
SELECT clob_col
INTO v_CLOBLocator
FROM lobdemo
WHERE key = -1
FOR UPDATE; -- Initialize the BFILE locator for reading.
v_FileLocator := BFILENAME(p_Directory, p_FileName);
DBMS_LOB.FILEOPEN(v_FileLocator, DBMS_LOB.FILE_READONLY); -- Set up the cursor.
v_SQLCursor := DBMS_SQL.OPEN_CURSOR; -- Load the entire file into the character LOB.
-- This is necessary so that we have the data in
-- character rather than RAW variables.
DBMS_LOB.LOADFROMFILE(v_CLOBLocator, v_FileLocator,
DBMS_LOB.GETLENGTH(v_FileLocator)); -- Loop over the LOB, searching for each occurrence of
-- the separation character.
LOOP
v_EndPoint := DBMS_LOB.INSTR(v_CLOBLocator, p_SeparationChar,
v_StartPoint, 1);
EXIT WHEN v_EndPoint = 0; -- Extract the contents between the starting and ending points.
-- This is the SQL statement to be executed.
v_StatementLength := v_EndPoint - v_StartPoint;
v_SQLStatement := DBMS_LOB.SUBSTR(v_CLOBLocator,
v_StatementLength, v_StartPoint); -- Echo the statement to the screen, and then execute it
-- using DBMS_SQL.
DBMS_OUTPUT.PUT_LINE(v_SQLStatement);
DBMS_SQL.PARSE(v_SQLCursor, v_SQLStatement, DBMS_SQL.V7);
v_RC := DBMS_SQL.EXECUTE(v_SQLCursor); -- Increment the statement pointer for the next statement.
v_StartPoint := v_EndPoint + 1;
END LOOP; -- Clean up.
DBMS_LOB.FILECLOSE(v_FileLocator);
DBMS_SQL.CLOSE_CURSOR(v_SQLCursor);
EXCEPTION
WHEN OTHERS THEN
-- Close the cursor and file, and reraise.
DBMS_LOB.FILECLOSE(v_FileLocator);
DBMS_SQL.CLOSE_CURSOR(v_SQLCursor);
RAISE;
END FileExec;
/