关于Oracle中varchar2和dbms_output.put_line的长度限制问题小结

一. varchar2长度限制问题

1) 表字段创建最大长度：4000

SQL> CREATE TABLE t_test1(a VARCHAR2(4000));
--正确

Table created.

SQL> CREATE TABLE t_test2(a VARCHAR2(4001));
--错误

CREATE TABLE t_test2(a VARCHAR2(4001))

*

ERROR at line 1:

ORA-00910: specified length too long for its datatype

2) plsql变量定义最大长度：32767

SQL> CREATE OR REPLACE PROCEDURE sp_test1 (p IN VARCHAR2 DEFAULT NULL ) --正确

IS

x_var VARCHAR2 (32767);

BEGIN

DBMS_OUTPUT.put_line (p);

END;

/

Procedure created.

SQL> CREATE OR REPLACE PROCEDURE sp_test2 (p IN VARCHAR2 DEFAULT NULL ) --错误

IS

x_var2 VARCHAR2 (32768);

BEGIN

NULL;

END;

/

Warning: Procedure created with compilation errors.

SQL> show error;

Errors for PROCEDURE SP_TEST2:

LINE/COL ERROR

-------- -----------------------------------------------------------------

3/23 PLS-00215: String length constraints must be in range (1 ..

32767)

3) plsql调用参数最大长度：65535

SQL> DECLARE

lv_test VARCHAR2 (32767);

BEGIN

FOR i IN 1 .. 32767

LOOP

lv_test := lv_test || '-';

END LOOP;

sp_test1 (LENGTHB (lv_test || lv_test || '1'));

END;

/

65535

SQL> DECLARE

lv_test VARCHAR2 (32767);

BEGIN

FOR i IN 1 .. 32767

LOOP

lv_test := lv_test || '-';

END LOOP;

sp_test1 (LENGTHB (lv_test || lv_test || '12'));

END;

/

DECLARE

*

ERROR at line 1:

ORA-06502: PL/SQL: numeric or value error: character string buffer too small

ORA-06512: at line 9

二. dbms_output.put_line长度限制问题

对于10g以上版本(包括10g), dbms_output.put_line的最大长度限制是32767.
如果报错buffer overflow, 执行如下语句即可:

set serveroutput ON SIZE UNLIMITED FORMAT WORD_WRAPPED

对于10g以下版本dbms_output.put_line最大长度限制是255.

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