Lazarus and MAria DB
lazarus / 16-Databases

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luzi3009 · 2020-12-17 14:31

Hi everyone

I'm trying to put Lazarus V2.0.0 in Connection with Maria DB10.3.X on
my Raspberry Pi.

I have installed everything and i can already reach the Database from
my Windows PC through HeidiSQL.

Now i'm want to set up the connection with Lazarus but i always get
the fault

"Can not load default mysql library ( libmysqlclient.so.18 or
libmysqlclient.so ) Check your installation"

I've tried with all MYSQL Connection. The Error is the same accept
from the clientnumber "18".

What do i have to do?

Thanks for your help

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devEric69 · 2020-12-17 14:51

Hello,

To resolve this error...

Quote from: luzi3009 on December 17, 2020, 03:31:21 pm"Can not load
default mysql library ( libmysqlclient.so.18 or libmysqlclient.so )
Check your installation"

...try to install the Mysql client package, version number 18, for
development, i.e. having probably a name like this globex: 
*libmysqlclient18*-dev*.deb .

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luzi3009 · 2020-12-17 18:13

When i try to install this package it tells me i have a newer version
and it will not be installed.

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devEric69 · 2020-12-19 19:13

In accordance with this summary (how the libraries loader works: https
://wiki.freepascal.org/File:lazarus_free_pascal_libraries_loading_unde
r_linux.png), you can do - almost - 2 different things:
- first, you can verify that there is a softlink from the link-name
libmysqlclient.so towards the soname libmysqlclient.so.19 (say, that
your already installed newer version is num# 19).
In this hypothesis, you can uninstall the new version (i.e. version
19), and install the old one (i.e. 18) with the development package
file *.deb . The development package will automatically complete your
installation by also creating the shortcut-softlink from the soname
*mysql*.so.18 towards the real library file *mysql*18.x.so.
- but, if you want to keep your newer version (say, version 19), then
you have to rely on MySQL backward compatibility (a.k.a. conservation
of the bottom-up compatibility of the APIs of the released libraries,
i.e. hope that a client library version 19 is always compatible with
client softwares targeted for a client library version 18). Let's say
that with a premium database server like MySQL or MariaDB, this should
be the case. However, this should be checked before. In such a
validated case, then you have to do the following manually shortcuts-
symlinks: 
 · libmysqlclient.so ==towards==> libmysqlclient.so.18
 · libmysqlclient.so.18 ==towards==> libmysqlclient.so.19
The shortcut-symlink libmysqlclient.so.19 should already exist and
point towards the newer installed *mysql*19.x.so library.

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luzi3009 · 2020-12-19 19:17

Hello Thanks for your help. I will try this tomorrow. But where is the
.so placed?

I do not find it in lib

Thanks

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devEric69 · 2020-12-20 10:57

AFAIK, the loader uses the following search paths, to resolve a
librairy loading, starting from a link-name or starting from a soname:
  ●  directories specified by the environment variable LD_RUN_PATH
  ●  directories specified by the environment variable LD_LIBRARY_PATH
  ●  directories specified in DT_RUNPATH or DT_RPATH field, when a
DT_SONAME and DT_NEEDED are present in the executable trying to launch
a shared library
  ●  default directories, normally /lib/* and /usr/lib/* (← most
likely locations, for a multi-clients database server)
  ●  commercial directories such as /opt/appli_name/*
  ●  directories listed in the /etc/ld.so.conf file, of course

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luzi3009 · 2020-12-20 11:12

i had a look in /lib/ and in /usr/lib and there is nothing with
libmysql.so but i find other .so i have installed earlier.
How do i install the libmysql.so now? I'm very confused because i
installed the MariaDb-client and it is all running

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luzi3009 · 2020-12-20 11:18

ok I solved the problem finally

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 sudo apt
install libmariadb-devsudo ln -s /usr/lib/arm-linux-
gnueabihf/libmariadbclient.so /usr/lib/arm-linux-
gnueabihf/libmysqlclient.so
i missed these 2 lines during installation.

But Thanks for your help. I made my understand the database direction
better.

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devEric69 · 2020-12-20 13:09

Quote from: luzi3009 on December 20, 2020, 12:18:47 pmok I solved the
problem finally

Well done!