select a table by field with non English characters
lazarus / 16-Databases

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mrkwlee · 2019-12-18 09:25

when  select * from mytable where myfield like '甲%' ,error of convert
coding is thrown out to halt the program.
I have tried to use UTF8Encode but it still does not work.  If I
replace '甲%' with any English  words like 'A%', it works.
database coding UTF8
My system is: win 10, Lazarus 2.0.6 , firebird 3, zeoslib 7,
I have google for 2 hours and got no answer.
Please help me.

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tonyw · 2019-12-18 11:24

Have you checked to ensure that the database connection is also using
UTF8 encoding? This is separate from the default database character
set.

It's probably also worth checking to ensure that the table column
character set is also UTF8.

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mrkwlee · 2019-12-19 01:26

thank you.
my connection code base is already UTF8.
I tried to set it to none yesterday, it works.
However, another problem come out is
var
  s: string;
begin
  s:='甲%';
  QZquery1.SQL.Text:='select * from mutable where desc like '
     +s;
....
end;
gives the same error as before.
I think the data type of s makes the problem. still not solved

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winni · 2019-12-19 01:55

Hi!

First for debugging support:

U+7532
甲
E794B2  // hex
15176882 //decimal
甲 // HTML

Belonging to the "monster" block  CJK Unified Ideographs.

Think about this:

If every component on the way from the database to the screen tries to
decode UTF8 then it has to give some rubbish or exception.

Try to decode a a decoded utf8 char (string). It must crash somehow.
So check that only one component does a decode and the other only
gives a rawstring to the next.

Winni

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mrkwlee · 2019-12-19 08:28

thank you very much for your debug help.
It is solved by setting
 zconnection codepage to none
       and clientcodepage to cpUTF8.