I only change a filter condition when filtered is false. So I would write your code as follows
zquery1.FilterOptions:=[foCaseInsensitive];
zquery1.Filtered := false;
if Length(Edit1.Text) > 0 then
begin
zquery1.Filter := 'client_id like ' + QuotedStr(trim(Edit1.Text)) ;
zquery1.Filtered := true;
end;
zquery2.FilterOptions:=[foCaseInsensitive];
zquery2.Filtered := false;
if Length(Edit1.Text) > 0 then
begin
zquery2.Filter := 'client_id like ' + QuotedStr('' + Edit1.Text + '') // Zeos- Syntax
zquery2.Filtered := true;
end;
zquery3.FilterOptions:=[foCaseInsensitive];
zquery3.Filtered := false;
if Length(Edit1.Text) > 0 then
begin
zquery3.Filter := 'client_id like ' + QuotedStr('' + Edit1.Text + '') // Zeos- Syntax
zquery3.Filtered := true;
end;
zquery3.FilterOptions:=[foCaseInsensitive];
zquery3.Filtered := false;
if Length(Edit1.Text) > 0 then
begin
zquery3.Filter := 'client_id like ' + QuotedStr('' + Edit1.Text + '') // Zeos- Syntax
zquery3.Filtered := true;
end;