access delete empty field records-Access-php.cn

access delete empty field records

王林

Release： 2020-12-01 15:46:57

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access delete empty field records

First of all, we need to know that null and empty string are different in Access, so if this problem is not handled well, it will cause a lot of trouble, especially in mixed queries.

(Recommended tutorial: access database learning)

The solution is as follows:

var
 SQLStr:string;
begin
//
  SQLStr := &#39;select * from ordertb where 1>0&#39;;
  if Trim(Edit1.Text)<>&#39;&#39; then
  SQLStr := SQLStr +&#39; and serialid like :a&#39;;
  if Trim(Edit2.Text)<>&#39;&#39; then
  SQLStr := SQLStr +&#39; and pname like :b&#39;;
 
  with ADOQuery1 do
  begin
    Close;
    SQL.Clear;
    SQL.Add(SQLStr);
    if Trim(Edit1.Text)<>&#39;&#39; then
    Parameters.ParamByName(&#39;a&#39;).Value := &#39;%&#39;+Trim(Edit1.Text)+&#39;%&#39;;
    if Trim(Edit2.Text)<>&#39;&#39;then
    Parameters.ParamByName(&#39;b&#39;).Value := &#39;%&#39;+Trim(Edit2.Text)+&#39;%&#39;;
    Open;
  end;
end;

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or:

begin  
  with ADOQuery1 do
  begin
    Close;
    SQL.Clear;
    SQL.Add(&#39;select * from ordertb where 1>0&#39;);
    if Trim(Edit1.Text)<>&#39;&#39; then
    SQL.Add(&#39; and serialid like &#39;&#39;%&#39;+Trim(Edit1.Text)+&#39;%&#39;&#39;&#39;);
    if Trim(Edit2.Text)<>&#39;&#39;then
    SQL.Add(&#39; and pname like &#39;&#39;%&#39;+Trim(Edit2.Text)+&#39;%&#39;&#39;&#39;);
    Open;
  end;
end;

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Summary :

Filter out fields with empty conditions from the query statement.

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