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Saturday, February 7, 2009

Trailing Blanks Error in Pro*C

http://www.cs.umbc.edu/help/oracle8.bak/server803/A54661_01/dev.htm#2416

char emp_name[10];
...
strcpy(emp_name, "MILLER"); /* WRONG! Note no blank-padding */
EXEC SQL INSERT INTO emp (empno, ename, deptno) VALUES
(1234, :emp_name, 20);

you will find that the string "MILLER" was inserted as "MILLER\0\0\0\0" (with four null bytes appended to it). This value does not meet the following search condition:

. . . WHERE ename = 'MILLER';

To INSERT the character array when DBMS is set to V6 or CHAR_MAP is set to VARCHAR2, you should execute the statements

strncpy(emp_name, "MILLER ", 10); /* 4 trailing blanks */
EXEC SQL INSERT INTO emp (empno, ename, deptno) VALUES
(1234, :emp_name, 20);

input data in a character array must be null-terminated. So, make sure that your data ends with a null.

char emp_name[11]; /* Note: one greater than column size of 10 */
...
strcpy(emp_name, "MILLER"); /* No blank-padding required */
EXEC SQL INSERT INTO emp (empno, ename, deptno) VALUES
(1234, :emp_name, 20);

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