Data from SQLite
lazarus / 16-Databases

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amedeo · 2019-11-23 12:39

Hallo, sorry for may bad english.
I am doing my first DB using Lazarus+SQLite and I have a ploblem
showing data in a TDBGrid.
I build DB and TABLE using "DB Browser for SQLite" and I populated the
TABLE with 3 recors. It is ok, I saw it.
In Lazarus I build the application with one form and:
TSQlite3Connection, TSQLTransaction, TSQLQery, TDataSorce and a
TDBGrid with all this objects connected, I thik, well. I see all
columns and the correct numbers of rows and the value of the first
field that is a interger AutoIncrement, in the remaining fields of the
TDBGrid I see just "MEMO".
Someone can help me to understand and solve this problem?
Thaks

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fmc · 2019-11-23 13:26

Try this:

Click on your DBGrid and go to your Object Inspector.
Scroll down and click Options, then tick dgDisplayMemoText.

 It's been a while since I used the stock DBGrid that comes with
Lazarus, but I think that'll do the trick for you.

Btw, your English is fine.

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Zvoni · 2019-11-23 13:42

And don't use AUTOINCREMENT on your Primary Key in SQLite

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fmc · 2019-11-23 14:11

To further Zvoni's reply, this is how it works:

If you have a table that's:
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 CREATE
TABLE IF NOT EXISTS customers(    cust_id INTEGER PRIMARY KEY,    
cust_fname VARCHAR(20),     cust_lname VARCHAR(20));
the cust_id column will increment on its own. However if the table
drops all rows, it starts from the beginning again.

As where if you use:
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 CREATE
TABLE IF NOT EXISTS customers(    cust_id INTEGER PRIMARY KEY
AUTOINCREMENT,     cust_fname VARCHAR(20),     cust_lname
VARCHAR(20));
and dropped a row (or all of them again), it will start with the last
cust_id that was in use. That's the difference.

So either works fine.

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valdir.marcos · 2019-11-23 14:12

Quote from: amedeo on November 23, 2019, 01:39:31 pmHallo, sorry for
may bad english.
I am doing my first DB using Lazarus+SQLite and I have a ploblem
showing data in a TDBGrid.
I build DB and TABLE using "DB Browser for SQLite" and I populated the
TABLE with 3 recors. It is ok, I saw it.
In Lazarus I build the application with one form and:
TSQlite3Connection, TSQLTransaction, TSQLQery, TDataSorce and a
TDBGrid with all this objects connected, I thik, well. I see all
columns and the correct numbers of rows and the value of the first
field that is a interger AutoIncrement, in the remaining fields of the
TDBGrid I see just "MEMO".
Someone can help me to understand and solve this problem?
ThaksIt will be easier to help you, if you attach a small sample
project.
Maybe, you should review your SQLite's table structure.

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Zvoni · 2019-11-23 14:42

Quote from: fmc on November 23, 2019, 03:11:57 pmTo further Zvoni's
reply, this is how it works:

If you have a table that's:
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 CREATE
TABLE IF NOT EXISTS customers(    cust_id INTEGER PRIMARY KEY,    
cust_fname VARCHAR(20),     cust_lname VARCHAR(20));
the cust_id column will increment on its own. However if the table
drops all rows, it starts from the beginning again.

As where if you use:
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 CREATE
TABLE IF NOT EXISTS customers(    cust_id INTEGER PRIMARY KEY
AUTOINCREMENT,     cust_fname VARCHAR(20),     cust_lname
VARCHAR(20));
and dropped a row (or all of them again), it will start with the last
cust_id that was in use. That's the difference.

So either works fine.
Yes, to a degree. The amount of data not withstanding, why i prefer no
AUTOINCREMENT in SQLite:
From the SQLite-Dox:
Quotef a column has the type INTEGER PRIMARY KEY AUTOINCREMENT then a
slightly different ROWID selection algorithm is used. The ROWID chosen
for the new row is at least one larger than the largest ROWID that has
ever before existed in that same table. If the table has never before
contained any data, then a ROWID of 1 is used. If the largest possible
ROWID has previously been inserted, then new INSERTs are not allowed
and any attempt to insert a new row will fail with an SQLITE_FULL
error. Only ROWID values from previous transactions that were
committed are considered. ROWID values that were rolled back are
ignored and can be reused.

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amedeo · 2019-11-23 16:42

Solved. A lot of thanks, the proble is just to check an option

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fmc · 2019-11-23 16:46

Yeah