Selecting Character Values

When you insert a character value into a CHAR database column, Oracle does not strip trailing blanks. If the value is shorter than the defined width of the column, Oracle blank-pads the value to the defined width. As a result, information about trailing blanks is lost. If the character value is longer than the defined width of the column, Oracle aborts the insert and generates an error.

When you insert a character value into a VARCHAR2 database column, Oracle does not strip trailing blanks. If the value is shorter than the defined width of the column, Oracle does not blank-pad the value. Character values are stored intact, so no information is lost. If the character value is longer than the defined width of the column, Oracle aborts the insert and generates an error.

Note: The same rules apply when updating.

When inserting character values, to ensure that no trailing blanks are stored, use the function RTRIM, which trims trailing blanks. An example follows:

DECLARE

...

my_name VARCHAR2(15); BEGIN

...

my_ename := 'LEE '; -- note trailing blanks INSERT INTO emp

VALUES (my_empno, RTRIM(my_ename), ...); -- inserts 'LEE'

END;

Selecting Character Values

When you select a value from an Oracle database column into a PL/SQL character variable, whether the value is blank-padded or not depends on the variable type, not on the column type.

When you select a column value into a CHAR variable, if the value is shorter than the declared length of the variable, PL/SQL blank-pads the value to the declared length. As a result, information about trailing blanks is lost. If the character value is longer than the declared length of the variable, PL/SQL aborts the assignment and raises

VALUE_ERROR.

When you select a column value into a VARCHAR2 variable, if the value is shorter than the declared length of the variable, PL/SQL neither blank-pads the value nor strips trailing blanks. Character values are stored intact, so no information is lost.

For example, when you select a blank-padded CHAR column value into a VARCHAR2 variable, the trailing blanks are not stripped. If the character value is longer than the declared length of the VARCHAR2 variable, PL/SQL aborts the assignment and raises

VALUE_ERROR.

Note: The same rules apply when fetching.

Understanding CHAR and VARCHAR2 Semantics in PL/SQL B-3

Selecting Character Values

B-4 PL/SQL User's Guide and Reference