asString x asInteger, when value is zero.
lazarus / 16-Databases

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zuibaf · 2017-12-18 19:46

In the database Postgresql, I defined the field as:

ball numeric not null,

When one register, have value '0' (zero), the property asString return
a empty string,
instead of returning a string with value '0'.

In the component TSqlQuery, when try access the valor as String, so:

var
   ball: string;
begin
sqlRegister := TSqlQuery.Create;
...
ball := sqlRegister.FieldByName('ball').asString,

asString, returned a empty string instead of a string with value zero.

I know I should use AsInteger because the value of the field in the
table is numeric, however, I am populating the data in a STRINGGRID.
However, I found that the behavior of asString was to convert the
value zero to a string with the value zero, however, it converts with
an empty string, behaving as if the field 'ball' had a null value,
which is not correct in this case.

The Workaround who I did was:
ball := IntToStr(sqlRegister.FieldByName('ball').asInteger);


My question is, Why asString should not return an empty string instead
of the value '0', when the value of the register field is 0???

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PatBayford · 2017-12-19 01:10

Is it possible that you have a setting in your database which converts
0 to null? I don't know PostgresSQL, but a lot of RDBMS systems have
these sort of settings buried in the configuration!
Try getting the value with AsInteger, then convert to string as a
check.

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GAN · 2017-12-19 04:30

Zero may be trated as null so the empty string it's correct.

To solve this, you can try StrToIntDef : http://lazarus-
ccr.sourceforge.net/docs/rtl/sysutils/strtointdef.html

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i function
StrToIntDef(  const S: ;  Default: Integer ): Integer;
Pass 0 (zero) as default.

Or simple use a conditional

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i if
sqlRegister.FieldByName('ball').asString='' then ball:=0;