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Database Forum / DB2 Topics / December 2005Any function in DB2 to help
to help to Replace the stupid Coding like SUBSTR('0000',LENGTH('22'),4-LENGTH('22'))||'22' changing string '22' to '0022' ??? > to help to Replace the stupid Coding like > SUBSTR('0000',LENGTH('22'),4-LENGTH('22'))||'22' > changing string '22' to '0022' ??? That is really stupid and slow coding. I would replace it if I had the chance.  SignatureKnut Stolze DB2 Information Integration Development IBM Germany Some ideas: SUBSTR('000'||'22',LENGTH('22')) SUBSTR(RIGHT('0000'||'22',4),1,4) DIGITS(DECIMAL('22',4,0)) > Some ideas: > SUBSTR('000'||'22',LENGTH('22')) > > SUBSTR(RIGHT('0000'||'22',4),1,4) > > DIGITS(DECIMAL('22',4,0)) I assumed that the given expression actually consisted of constants only. So there would be no need to do the calculation on the constants but rather write the results there directly. SignatureKnut Stolze DB2 Information Integration Development IBM Germany To make that itself shorter: REPEAT('0', 4 - LENGTH('22')) || '22' B. > To make that itself shorter: > > REPEAT('0', 4 - LENGTH('22')) || '22' > > B. Which is not quite the best you can do if the '22' in the example really stands for a CHARACTER expression. RIGHT('0000'||'22',4) is, I think, the best in the case of a CHARACTER expression. Under the presumption that the '22' in the example really stands for an integer expression, a more general solution is RIGHT(CHAR(10000+22),4). The 10000 and the 4 in the expression can be adjusted trivially for any reasonable number of leading zeroes. This is optimal in that it requires only one evaluation of the expression. Negative numbers, decimal expressions, etc. are left as an exercise for the interested reader :-) REPEAT and RIGHT are SYSFUN schema, and returns VARCHAR(4000). This fact sometime make things problematic or troublesome. For example, if you use CLP or Command Editor, a long column appears in the result. ------------------------- Commands Entered ------------------------- VALUES REPEAT('0', 4 - LENGTH('22')) || '22'; ------------------------------------------------------------------- 1 -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 0022 1 record(s) selected. So, I enclosed those expressions by SUBSTR. Like following. ------------------------ Commands Entered ------------------------- VALUES SUBSTR(RIGHT('0000'||'22',4),1,4); ------------------------------------------------------------------- VALUES SUBSTR(RIGHT('0000'||'22',4),1,4) 1 ---- 0022 1 record(s) selected. Yeah, i know, the CLP is my main environment. :) But inside a script, it shouldn't matter much, as the declaration of the variable should handle it. (Unless of course, he's using a version 7 Windows client to connect via ODBC to a version 8 Solaris server, in which case a SUBSTR would crash the server when the last parameter was out of range. :) ) B. ah.. i quite agree with you , and i write a function to do that ----------------------------- CREATE FUNCTION F_FILLSTR(V_TAR VARCHAR(256),V_CNT INTEGER ) RETURNS VARCHAR(512) LANGUAGE SQL NO EXTERNAL ACTION BEGIN ATOMIC DECLARE COMSTR VARCHAR(256); SET COMSTR = SPACE(V_CNT); SET COMSTR = REPLACE(COMSTR,' ','0'); SET COMSTR = COMSTR||RTRIM(V_TAR); SET COMSTR = RIGHT(COMSTR,V_CNT); RETURN COMSTR; END@ ----------------------------- run "values f_fillstr('aa',8)" : result 000000aa then i make a more general one and compile it successfully , but when i runs , a trouble comes , saying "SQL0440N No authorized routine name F_FILLSTR .... " ----------------------------- CREATE FUNCTION F_FILLSTR(V_TAR VARCHAR(256),V_SUSTR CHAR(1),V_CNT INTEGER ) RETURNS VARCHAR(512) LANGUAGE SQL NO EXTERNAL ACTION BEGIN ATOMIC DECLARE COMSTR VARCHAR(256); SET COMSTR = SPACE(V_CNT); SET COMSTR = REPLACE(COMSTR,' ',V_SUSTR); SET COMSTR = COMSTR||RTRIM(V_TAR); SET COMSTR = RIGHT(COMSTR,V_CNT); RETURN COMSTR; END@ ----------------------------- any help again ?? thx a lot . ah.. i quite agree with you , and i write a function to do that . ----------------------------- CREATE FUNCTION F_FILLSTR(V_TAR VARCHAR(256),V_CNT INTEGER ) RETURNS VARCHAR(512) LANGUAGE SQL NO EXTERNAL ACTION BEGIN ATOMIC DECLARE COMSTR VARCHAR(256); SET COMSTR = SPACE(V_CNT); SET COMSTR = REPLACE(COMSTR,' ','0'); SET COMSTR = COMSTR||RTRIM(V_TAR); SET COMSTR = RIGHT(COMSTR,V_CNT); RETURN COMSTR; END@ ----------------------------- run "values f_fillstr('aa',8)" : result 000000aa then i make a more general one and compile it successfully , but when i runs , a trouble comes , saying "SQL0440N No authorized routine name F_FILLSTR .... " ----------------------------- CREATE FUNCTION F_FILLSTR(V_TAR VARCHAR(256),V_SUSTR CHAR(1),V_CNT INTEGER ) RETURNS VARCHAR(512) LANGUAGE SQL NO EXTERNAL ACTION BEGIN ATOMIC DECLARE COMSTR VARCHAR(256); SET COMSTR = SPACE(V_CNT); SET COMSTR = REPLACE(COMSTR,' ',V_SUSTR); SET COMSTR = COMSTR||RTRIM(V_TAR); SET COMSTR = RIGHT(COMSTR,V_CNT); RETURN COMSTR; END@ ----------------------------- any help again ?? thx a lot . My guess is that you use the function like F_FILLSTR('aa', 'x', 8). If so, V_SUSTR CHAR(1) is the root of problem. Try V_SUSTR VARCHAR(1). Because data type of string constant(for example 'x') is VARCHAR. >Which is not quite the best you can do if the '22' in the example really >stands for a CHARACTER expression. RIGHT('0000'||'22',4) is, I think, >the best in the case of a CHARACTER expression. Mostly, i was reponding how to keep the current logic there, so i used REPEAT instead of SUBSTR. For myself, i agree i would use RIGHT('0000'||'22',4), because it makes more sense to me. But, exactly why do you think it best? Just because its straight forward? Or is there something i am missing? B. >>Which is not quite the best you can do if the '22' in the example really >>stands for a CHARACTER expression. RIGHT('0000'||'22',4) is, I think, [quoted text clipped - 8 lines] > > B. Single evaluation of the parameter '22'. It makes no sense if it is a constant, no difference if it is a single column, but it could be very important if it were a complex expression in its own right. Good coding practice, even in the simple cases, will lead to better results in the harder ones. Good point. Thanx. B. |
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