In my project i use oracle as primary database and i've faced a problem with parsing clob. So suppose we have a clob with value
aaaaaa
cccccc
bbbbbb
And it's stored in table test ...
I need to write plsql procedure to get this clob and split it so that i will have array with three items [aaaaaa,cccccccc,bbbbbbb].
Is there any possible solutions?
Pierre-Gilles Levallois
Here is a piece of code that works. I suggest that you use explicit cursors instead of implicit ones (FOR i IN (select...)), for performance purpose.
First here is the script to create testcase.
create table test (c clob);
insert into test (c) values (
'azertyuiop
qsdfghjklm
wxcvbn
');
Then here is the script to read line by line Clob :
/* Formatted on 28/08/2012 14:16:52 (QP5 v5.115.810.9015) */
declare
nStartIndex number := 1;
nEndIndex number := 1;
nLineIndex number := 0;
vLine varchar2(2000);
cursor c_clob is
select c from test;
c clob;
-------------------------------
procedure printout
(p_clob in out nocopy clob) is
offset number := 1;
amount number := 32767;
len number := dbms_lob.getlength(p_clob);
lc_buffer varchar2(32767);
i pls_integer := 1;
begin
if ( dbms_lob.isopen(p_clob) != 1 ) then
dbms_lob.open(p_clob, 0);
end if;
amount := instr(p_clob, chr(10), offset);
while ( offset < len )
loop
dbms_lob.read(p_clob, amount, offset, lc_buffer);
dbms_output.put_line('Line #'||i||':'||lc_buffer);
offset := offset + amount;
i := i + 1;
end loop;
if ( dbms_lob.isopen(p_clob) = 1 ) then
dbms_lob.close(p_clob);
end if;
exception
when others then
dbms_output.put_line('Error : '||sqlerrm);
end printout;
---------------------------
begin
dbms_output.put_line('-----------');
open c_clob;
loop
fetch c_clob into c;
exit when c_clob%notfound;
printout(c);
end loop;
close c_clob;
end;
'amount' variable is used to detect end of line position. Be carfull, in some case the end of line is CHR(10)||CHR(13) (CR + LF), and in some other cases it is only CHR(10).
While the SQL regexp / connect by level approach is probably the most elegant, it is quite bad performancewise (for my testcase on 11.2.0.3.0). Much faster is a simple parse like this.
procedure parse_clob(p_clob in clob) is
l_offset pls_integer:=1;
l_line varchar2(32767);
l_total_length pls_integer:=length(p_clob);
l_line_length pls_integer;
begin
while l_offset<=l_total_length loop
l_line_length:=instr(p_clob,chr(10),l_offset)-l_offset;
if l_line_length<0 then
l_line_length:=l_total_length+1-l_offset;
end if;
l_line:=substr(p_clob,l_offset,l_line_length);
dbms_output.put_line(l_line); --do line processing
l_offset:=l_offset+l_line_length+1;
end loop;
end parse_clob;
Jürgen Sieben
In case... - you have APEX installed - and the clob is less than 32K you may also want to look into the following code:
declare
l_text varchar2(32767) := '...';
l_rows wwv_flow_global.vc_arr2;
begin
l_rows := apex_util.string_to_table(l_text, chr(10));
for i in 1 .. l_rows.count loop
dbms_output.put_line(l_rows(i));
end loop;
end;
/
sample for dynamicly length of rows
and alternative for UNIX and WIN files
and CR/LF on end of file or without it
Create table for TEST
drop table pbrev.test_SVT_tmp; create table pbrev.test_SVT_tmp (xc clob); insert into pbrev.test_SVT_tmp (xc) values ( --'azertyuiop;11' || chr(13) || chr(10) ||'qsdfghjklm;7878' || chr(13) || chr(10) ||'wxcvbn;0' || chr(13) || chr(10) ); 'azertyuiop;11' || chr(13) || chr(10) ||'qsdfghjklm;7878' || chr(13) || chr(10) ||'wxcvbn;0' ); 'azerty jhjh huiop;11 qsdfgkj hjklhhhhhhhhhhhm;7878 wxcvbn;0 dkjsk kjdsk5456 4654 5646 54645 FINISH' ); delete from pbrev.test_SVT_tmp ; select xc from pbrev.test_SVT_tmp;
--SET SERVEROUTPUT ON;
--SET SERVEROUTPUT OFF;
declare
nStartIndex number := 1;
nEndIndex number := 1;
nLineIndex number := 0;
vLine varchar2(2000);
cursor c_clob is
select xc from pbrev.test_SVT_tmp;
c clob;
procedure printout
(p_clob in out nocopy clob) is
offset number := 1;
amount number := 32767;
amount_last number := 0;
len number := dbms_lob.getlength(p_clob);
lc_buffer varchar2(32767);
line_seq pls_integer := 1;
-- For UNIX type file - replace CHR(13) to NULL
CR char := chr(13);
--CR char := NULL;
LF char := chr(10);
nCRLF number;
sCRLF varchar2(2);
b_finish boolean := true;
begin
sCRLF := CR || LF;
nCRLF := Length(sCRLF);
if ( dbms_lob.isopen(p_clob) != 1 ) then
dbms_lob.open(p_clob, 0);
end if;
amount := instr(p_clob, sCRLF, offset);
while ( offset < len )
loop
-- For without CR/LF on end file
If amount < 0 then
amount := len - offset + 1;
b_finish := false;
End If;
dbms_lob.read(p_clob, amount, offset, lc_buffer);
If b_finish then
lc_buffer := SUBSTR(lc_buffer,1,Length(lc_buffer)-1);
End If;
if (line_seq-1) > 0 then
amount_last := amount_last + amount;
offset := offset + amount;
else
amount_last := amount;
offset := amount + nCRLF;
end if;
amount := instr(p_clob, sCRLF, offset);
amount := amount - amount_last;
dbms_output.put_line('Line #'||line_seq||': '||lc_buffer);
line_seq := line_seq + 1;
end loop;
if ( dbms_lob.isopen(p_clob) = 1 ) then
dbms_lob.close(p_clob);
end if;
exception
when others then
dbms_output.put_line('Error : '||sqlerrm);
end printout;
begin
open c_clob;
loop
fetch c_clob into c;
exit when c_clob%notfound;
printout(c);
end loop;
close c_clob;
end;
This is a follow-up answer based on @Pierre-Gilles Levallois his answer. Since I think it contained some bugs, I've tried to fix them.
- Empty lines caused errors
- Newlines where still in the print output (might be desired)
- "amount :=" was not inside the while loop, i think this caused a big bug if any value was shorter than the first line in the CLOB
I've implemented this as rather quick and dirty fixes. I'm sure there should be more elegant solutions... Here goes. The example table:
create table test (c clob);
insert into test (c) values (
-- line 1 (empty)
chr(10)||'line 2'
||chr(10) -- line 3 (empty)
||chr(10)||'line 4'
||chr(10)||'line 5'
||chr(10)); -- line 6 (empty)
And the altered code:
set serveroutput on;
declare
cursor c_clob is
select c from test;
c clob;
-------------------------------
procedure printout
(p_clob in out nocopy clob) is
offset number := 1;
amount number := 32767;
len number := dbms_lob.getlength(p_clob);
lc_buffer varchar2(32767);
i pls_integer := 1;
begin
if ( dbms_lob.isopen(p_clob) != 1 ) then
dbms_lob.open(p_clob, 0);
end if;
while ( offset < len )
loop
-- If no more newlines are found, read till end of CLOB
if (instr(p_clob, chr(10), offset) = 0) then
amount := len - offset + 1;
else
amount := instr(p_clob, chr(10), offset) - offset;
end if;
-- This is to catch empty lines, otherwise we get a NULL error
if ( amount = 0 ) then
lc_buffer := '';
else
dbms_lob.read(p_clob, amount, offset, lc_buffer);
end if;
dbms_output.put_line('Line #'||i||':'||lc_buffer);
-- This is to catch a newline on the last line with 0 characters behind it
i := i + 1;
if (instr(p_clob, chr(10), offset) = len) then
lc_buffer := '';
dbms_output.put_line('Line #'||i||':'||lc_buffer);
end if;
offset := offset + amount + 1;
end loop;
if ( dbms_lob.isopen(p_clob) = 1 ) then
dbms_lob.close(p_clob);
end if;
exception
when others then
dbms_output.put_line('Error : '||sqlerrm);
end printout;
---------------------------
begin
dbms_output.put_line('-----------');
open c_clob;
loop
fetch c_clob into c;
exit when c_clob%notfound;
printout(c);
end loop;
close c_clob;
end;
user1361991
This is an elegant solution that works just fine with clobs exceeding 32767 chars or lines exceeding 4K characters.
ANSI Standard Query:
DECLARE
v_tmp clob :='aaaa'||chr(10)||
'bbb'||chr(10)||
'ccccc';
BEGIN
FOR rec IN (WITH clob_table(c) as (SELECT v_tmp c FROM DUAL),
recurse(text,line) as (SELECT regexp_substr(c, '.+', 1, 1) text,1 line
FROM clob_table
UNION ALL
SELECT regexp_substr(c, '.+', 1, line+1),line+1
FROM recurse r,clob_table
WHERE line<regexp_count(c, '.+'))
SELECT text,line FROM recurse) LOOP
dbms_output.put_line(rec.text);
END LOOP;
END;
Oracle Specific Query (original post):
DECLARE
v_tmp clob :='aaaa'||chr(10)||
'bbb'||chr(10)||
'ccccc';
BEGIN
FOR rec IN (WITH clob_table(c) as (SELECT v_tmp c FROM DUAL)
SELECT regexp_substr(c, '.+', 1, level) text,level line
FROM clob_table
CONNECT BY LEVEL <= regexp_count(c, '.+')) LOOP
dbms_output.put_line(rec.text);
END LOOP;
END;
I created a table called lixo_mq:
CREATE TABLE LIXO_MQ (CAMPO1 VARCHAR2(4000))
I copied printout procedure and changed it to work different:
PROCEDURE PRINTOUT (P_CLOB IN OUT NOCOPY CLOB) IS
V_APARTIR NUMBER (20);
V_CONTAR NUMBER (20);
V_LINHA VARCHAR2 (4000);
V_REG NUMBER (20);
V_CORINGA VARCHAR2 (10) := CHR (10);
V_ERRO VARCHAR2 (4000);
BEGIN
IF (DBMS_LOB.ISOPEN (P_CLOB) != 1) THEN
DBMS_LOB.OPEN (P_CLOB, 0);
END IF;
V_APARTIR := 1;
V_REG := 1;
WHILE DBMS_LOB.INSTR (LOB_LOC => P_CLOB
,PATTERN => V_CORINGA
,OFFSET => 1
,NTH => V_REG
) > 0
LOOP
V_CONTAR :=
DBMS_LOB.INSTR (LOB_LOC => P_CLOB
,PATTERN => V_CORINGA
,OFFSET => 1
,NTH => V_REG
)
- V_APARTIR;
IF V_APARTIR > 1 THEN
V_LINHA :=
DBMS_LOB.SUBSTR (LOB_LOC => P_CLOB
,AMOUNT => V_CONTAR
- 1
,OFFSET => V_APARTIR
+ 1
);
ELSE
V_LINHA :=
DBMS_LOB.SUBSTR (LOB_LOC => P_CLOB
,AMOUNT => V_CONTAR
,OFFSET => V_APARTIR
);
END IF;
INSERT INTO LIXO_MQ
(CAMPO1
)
VALUES ( V_REG
|| ':'
|| V_LINHA
);
COMMIT;
V_APARTIR :=
DBMS_LOB.INSTR (LOB_LOC => P_CLOB
,PATTERN => V_CORINGA
,OFFSET => 1
,NTH => V_REG
);
V_REG := V_REG
+ 1;
END LOOP;
IF (DBMS_LOB.ISOPEN (P_CLOB) = 1) THEN
DBMS_LOB.CLOSE (P_CLOB);
END IF;
EXCEPTION
WHEN OTHERS THEN
V_ERRO := 'Error : '
|| SQLERRM;
INSERT INTO LIXO_MQ
(CAMPO1
)
VALUES (V_ERRO
);
COMMIT;
END PRINTOUT;
declare
c_clob clob := empty_clob();
c_offset number;
c_len number;
read_cnt number;
prev_buf number := 0;
read_str varchar2(32000);
BEGIN
-- Read the clob in to the local variable
select c into c_clob from test;
c_offset := 1;
-- Get the length of the clob
c_len := dbms_lob.getlength(c_clob);
-- Read till the current offset is less the length of clob
while(c_offset <= c_len)
loop
-- Get the index of the next new line character
read_cnt := instr(c_clob, CHR(10), c_offset, 1);
exit when read_cnt = 0;
-- Read the clob in the index
read_str := dbms_lob.substr(c_clob, read_cnt-c_offset, c_offset);
dbms_output.put_line('Line#' || read_str);
-- Now the current offset should point after the read line
c_offset := read_cnt+1;
end loop;
END;
/
来源：https://stackoverflow.com/questions/11647041/reading-clob-line-by-line-with-pl-sql