ZMSQL question and TBufdataset usage
lazarus / 16-Databases

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Ronan · 2016-11-22 16:40

Dear All,

My first question is: Can ZMSQL connect to the other format type of
databases or does it understand only the XML or CSV formatted datbases
?

My second question is: In order to understand the usage of
TBufDataset, I use the following code, but interesting thing is locate
fnction always returns the true, regarding the code below It's never
even supposed to retrieve the true value, but why it behaves in that
way ?

Your help will be really appreciated,

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 var  BufDS
:TBufDataset;  i:INteger;  str :string;begin  BufDS :=
TBufDataset.Create(Self);  bufDS.FieldDefs.Add('Test_Field',
ftString);   bufDS.CreateDataset;  bufDS.Open;   for i := 0 to 5000
do  begin    bufDS.Append;    bufDS.FieldByName('Test_Field').value:=
'new_value-'+IntToStr(i);    bufDS.Post;   end;    bufDS.First;   if
bufDS.Locate('Test_Field',1000,[]) then     str := 'correct';

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LacaK · 2016-11-22 18:23

To second question:
  In case of ftString fields you must specify Size (else is 0 which
leads to strange results):
    bufDS.FieldDefs.Add('Test_Field', ftString, 14);

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tatamata · 2016-12-02 12:18

Zmsql loads and save from CSV files by using
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 procedure
LoadFromTable; //Loads data (or data and schema) from a .csv file
(TableName.csv), set in property TableName, from path specified in
ZMConnection property.procedure SaveToTable;overload; //Saves data and
schema to a .csv file (TableName.csv), set in Tablename property, in
path specified in ZMConnection property.
But, it can also load data from any other TDaset descendent
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 procedure
CopyFromDataset (pDataset:TDataSet); //Copies schema and data from any
TDataset.
It can also just create memory dataset
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 procedure
MemoryDataSetOpen; //Executes CreateDynamicFieldsFromFieldDefs and set
dataset to Active.
or it can create memory dataset as result of SQL query executed on CSV
files
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 procedure
QueryExecute; //Executes SQL query defined in SQL property, on .csv
files that are placed in folder defined in ZMConnection property.
Resultset of select query is loaded into the the zmquerydataset
(self).