delphi使用SQL的教程7
{ Initialize the variables needed to run the query }
with ListBox1 do
if ItemIndex = -1 then
raise Exception.Create(’Can’’t Run Query: No Alias Selected’)
else
strAlias := Items.Strings[ItemIndex];
with ListBox2 do
if ItemIndex = -1 then
raise Exception.Create(’Can’’t Run Query: No Table Selected’)
else
strTable := Items.Strings[ItemIndex];
with ListBox3 do
if ItemIndex = -1 then
begin
if ComboBox1.ItemIndex > Ord(soNocondition) then
raise Exception.Create(’Can’’t Run Query: No Field Selected’)
else
strField := ’’;
end
else
strField := Items.Strings[ItemIndex];
if (Edit1.Text = ’’) and
(ComboBox1.ItemIndex > Ord(soNoCondition)) and
(ComboBox1.ItemIndex < Ord(soBlank)) then
raise Exception.create(’Can’’t Run Query: No Search Value Entered’)
else
strValue := Edit1.Text;
{ See if the field being search is a string field. If so, then pad the
quote string with quotation marks; otherwise, set it to a null value. }
if strField <> ’’ then
with Table1.FieldByName(strField) do
if (DataType = ftString) or (DataType = ftMemo) then
strQuote := ’"’ else
strQuote := ’’;
{ Construct the WHERE clause of the query based on the user’s choice
in Type. }
case etSQLOps(ComboBox1.ItemIndex) of
soNoCondition: strWhere := ’’;
soEqual: strWhere := strField + ’ = ’ + strQuote + strValue+ strQuote;
soNotEqual: strWhere := strField + ’ <> ’ + strQuote + strValue +
strQuote;
soLessThan: strWhere := strField + ’ < ’ + strQuote + strValue +
strQuote;
soLessEqual: strWhere := strField + ’ <= ’ + strQuote + strValue +
strQuote;
soMoreThan: strWhere := strField + ’ > ’ + strQuote + strValue +
strQuote;
soMoreEqual: strWhere := strField + ’ >= ’ + strQuote + strValue +
strQuote;
soStartsWith: strWhere := strField + ’ LIKE ’ + strQuote +
strValue + ’%’ + strQuote;
soNoStartsWith: strWhere := strField + ’ NOT LIKE ’ + strQuote +
strValue + ’%’ + strQuote;
soEndsWith: strWhere := strField + ’ LIKE ’ + strQuote +
’%’ + strValue + strQuote;
soNoEndsWith: strWhere := strField + ’ NOT LIKE ’ +
strQuote + ’%’ + strValue + strQuote;
soContains: strWhere := strField + ’ LIKE ’+ strQuote+’%’+ strValue
+ ’%’ + strQuote;
soNoContains: strWhere := strField + ’ NOT LIKE ’ + strQuote + ’%’
+ strValue + ’%’ + strQuote;
soBlank: strWhere := strField + ’ IS NULL’;
soNotBlank: strWhere := strField + ’ IS NOT NULL’;
end;
if ComboBox1.ItemIndex = Ord(soNoCondition) then
strQuery := ’SELECT * FROM "’ + strTable + ’"’
else if Table1.FieldByName(strField).DataType = ftString then
strQuery := ’SELECT * FROM "’ + strTable + ’" t WHERE t.’ + strWhere
else
strQuery := ’SELECT * FROM "’ + strTable + ’" t WHERE t.’ + strWhere;
{ Create an instance of the browser form. }
frmQuery := TResultForm.Create(Application);
