sql - ORA-06502 : character string buffer too small. 即使字符串大小低于声明的大小限制

Question

 FOR this_loop
     IN (SELECT field_A, field_B
           FROM TABLE_NAME
          WHERE    num = i_num)
  LOOP
     IF this_loop.field_B BETWEEN 1 AND 3
     THEN
        v_A :=  v_A || ' ' || this_loop.field_A;
     ELSIF this_loop.field_B BETWEEN 4 AND 8
     THEN
        v_field_A := v_field_A || ' ' || this_loop.field_A;  -- Error is at this line
     ELSIF this_loop.field_B BETWEEN 9 AND 15
     THEN
        v_B :=  v_B || ' ' || this_loop.field_A;
     END IF;
  END LOOP;

变量声明为

v_field_A            VARCHAR2 (100);

我知道的 -

变量 v_field_A 的值不能超过 100 个字符

我从 SELECT 得到的输出查询不超过 10 个字符。

我的问题 - 当字符在 varchar2 的限制范围内时，如何解决空间缓冲区的问题？
几年前我遇到过这个问题，但上次原因是输出 select询问。它有超过 100 个字符，因此存在大小问题，但这次不超过 10 个字符。我糊涂了。任何帮助表示赞赏

Answer 1

Variable v_field_A cannot hold value more than 100 characters

为什么不？很有可能，因为你是 串联 中每一行的变量循环光标 .

例如，

SQL> DECLARE
  2    v_name VARCHAR2(50);
  3  BEGIN
  4    FOR i IN
  5    (SELECT ename FROM emp
  6    )
  7    LOOP
  8      v_name := v_name || i.ename;
  9    END LOOP;
 10  END;
 11  /
DECLARE
*
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
ORA-06512: at line 8

使用 DBMS_OUTPUT 查看变量的当前大小和附加的新值。

让我们调试

SQL> DECLARE
  2    v_name VARCHAR2(50);
  3  BEGIN
  4    FOR i IN
  5    (SELECT ename FROM emp
  6    )
  7    LOOP
  8      dbms_output.put_line('Length of new value = '||LENGTH(i.ename));
  9      v_name := v_name || i.ename;
 10      dbms_output.put_line('Length of variable = '||LENGTH(v_name));
 11    END LOOP;
 12  END;
 13  /
Length of new value = 5
Length of variable = 5
Length of new value = 5
Length of variable = 10
Length of new value = 4
Length of variable = 14
Length of new value = 5
Length of variable = 19
Length of new value = 6
Length of variable = 25
Length of new value = 5
Length of variable = 30
Length of new value = 5
Length of variable = 35
Length of new value = 5
Length of variable = 40
Length of new value = 4
Length of variable = 44
Length of new value = 6
Length of variable = 50
Length of new value = 5

错误

DECLARE
*
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
ORA-06512: at line 9

很明显，我们想要连接长度为 5 的字符串。到声明为最大大小的变量 50 ，当前持有大小为 50 的值.因此，它抛出错误 ORA-06502: PL/SQL: numeric or value error: character string buffer too small .