Example: TDbf (creating table and indexes, selecting of index): what changed

Revision 2 to 3. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		This example was taken from the post at the forum:\
2	2		<http://forum.lazarus.freepascal.org/index.php/topic,31169.msg199356.html#msg199356>
3	3
4	4		You can copy text to files:
5	5
6	6		- Code: mainaddindex.pas
7	7		- Form: mainaddindex.lfm
8	8
9	9		and test it.
10	10
11	11		### Code
12	12
13	13		``` pascal
14	14		unit MainAddIndex;
15	15
16	16		{$mode objfpc}{$H+}
17	17
18	18		interface
19	19
20	20		uses
21	21		Classes, SysUtils, db, dbf, Forms, Controls, Graphics, Dialogs,
22	22		DBGrids, DbCtrls, StdCtrls, LazFileUtils;
23	23
24	24		const
25	25		CountriesFilename = 'countries.dbf';
26	26
27	27		type
28	28
29	29		{ TForm1 }
30	30
31	31		TForm1 = class(TForm)
32	32		BSortByCountry: TButton;
33	33		BSortByCapital: TButton;
34	34		BSortByID: TButton;
35	35		dbfSource: TDataSource;
36	36		grid: TDBGrid;
37	37		Navigator: TDBNavigator;
38	38		procedure BSortByCapitalClick(Sender: TObject);
39	39		procedure BSortByCountryClick(Sender: TObject);
40	40		procedure BSortByIDClick(Sender: TObject);
41	41		procedure FormCreate(Sender: TObject);
42	42		procedure FormDestroy(Sender: TObject);
43	43		private
44	44		CountriesDbf: TDbf;
45	45		public
46	46		{ public declarations }
47	47		end;
48	48
49	49		var
50	50		Form1: TForm1;
51	51
52	52		implementation
53	53
54	54		{$R *.lfm}
55	55
56	56		{ TForm1 }
57	57
58	58		procedure TForm1.FormCreate(Sender: TObject);
59	59		begin
60	60		CountriesDbf:=TDbf.Create(Self);
61	61		CountriesDbf.TableName:=CountriesFilename;
62	62		if not FileExistsUTF8(CountriesFilename) then with CountriesDbf do begin
63	63		TableLevel:=7;
64	64		Exclusive:=True;
65	65		FieldDefs.Add('ID', ftAutoInc, 0, True);
66	66		FieldDefs.Add('CountryName', ftString, 25, True);
67	67		FieldDefs.Add('Capital', ftString, 25, True);
68	68		CreateTable;
69	69		Open;
70	70		Append;
71	71		// Fields[0].AsInteger:=100; // Do not fill 'ID' because its type is ftAutoInc
72	72		fields[1].AsString:='France';
73	73		Fields[2].AsString:='Paris';
74	74		Post;
75	75		Append;
76	76		// Fields[0].AsInteger:=101;
77	77		fields[1].AsString:='Egypt';
78	78		Fields[2].AsString:='Cairo';
79	79		Post;
80	80		Append;
81	81		// Fields[0].AsInteger:=102;
82	82		fields[1].AsString:='Indonesia';
83	83		Fields[2].AsString:='Jakarta';
84	84		Post;
85	85		Append;
86	86		// Fields[0].AsInteger:=103;
87	87		fields[1].AsString:='Austria';
88	88		Fields[2].AsString:='Vienna';
89	89		Post;
90	90		AddIndex('idxByID', 'ID', [ixPrimary,ixUnique]);
91	91		AddIndex('idxByCountry', 'CountryName', [ixCaseInsensitive]);
92	92		AddIndex('idxByCapital', 'Capital', [ixCaseInsensitive]);
93	93		end;
94	94		CountriesDbf.Open;
95	95		dbfSource.DataSet:=CountriesDbf;
96	96		grid.DataSource:=dbfSource;
97	97		Navigator.DataSource:=dbfSource;
98	98		end;
99	99
100	100		procedure TForm1.BSortByCapitalClick(Sender: TObject);
101	101		begin
102	102		CountriesDbf.IndexName:='idxByCapital';
103	103		end;
104	104
105	105		procedure TForm1.BSortByCountryClick(Sender: TObject);
106	106		begin
107	107		CountriesDbf.IndexName:='idxByCountry';
108	108		end;
109	109
110	110		procedure TForm1.BSortByIDClick(Sender: TObject);
111	111		begin
112	112		CountriesDbf.IndexName:='idxByID';
113	113		end;
114	114
115	115		procedure TForm1.FormDestroy(Sender: TObject);
116	116		begin
117	117		with CountriesDbf do begin
118	118		CloseIndexFile('idxByCapital');
119	119		CloseIndexFile('idxByCountry');
120	120		CloseIndexFile('idxByID');
121	121		end;
122	122		CountriesDbf.Close;
123	123		end;
124	124
125	125		end.
126	126		```
127	127
128	128		### Form
129	129
130		-	~~``` pascal~~
	130	+	``` lfm
131	131		object Form1: TForm1
132	132		Left = 229
133	133		Height = 270
134	134		Top = 94
135	135		Width = 420
136	136		Caption = 'Form1'
137	137		ClientHeight = 270
138	138		ClientWidth = 420
139	139		OnCreate = FormCreate
140	140		OnDestroy = FormDestroy
141	141		LCLVersion = '1.6.0.2'
142	142		object grid: TDBGrid
143	143		Left = 0
144	144		Height = 200
145	145		Top = 0
146	146		Width = 420
147	147		Align = alTop
148	148		Color = clWindow
149	149		Columns = <>
150	150		TabOrder = 0
151	151		end
152	152		object Navigator: TDBNavigator
153	153		Left = 0
154	154		Height = 25
155	155		Top = 200
156	156		Width = 420
157	157		Align = alTop
158	158		BevelOuter = bvNone
159	159		ChildSizing.EnlargeHorizontal = crsScaleChilds
160	160		ChildSizing.EnlargeVertical = crsScaleChilds
161	161		ChildSizing.ShrinkHorizontal = crsScaleChilds
162	162		ChildSizing.ShrinkVertical = crsScaleChilds
163	163		ChildSizing.Layout = cclLeftToRightThenTopToBottom
164	164		ChildSizing.ControlsPerLine = 100
165	165		ClientHeight = 25
166	166		ClientWidth = 420
167	167		Options = []
168	168		TabOrder = 1
169	169		end
170	170		object BSortByCountry: TButton
171	171		Left = 12
172	172		Height = 23
173	173		Top = 234
174	174		Width = 101
175	175		AutoSize = True
176	176		Caption = 'Sort by country'
177	177		OnClick = BSortByCountryClick
178	178		TabOrder = 2
179	179		end
180	180		object BSortByCapital: TButton
181	181		Left = 168
182	182		Height = 23
183	183		Top = 234
184	184		Width = 95
185	185		AutoSize = True
186	186		Caption = 'Sort by capital'
187	187		OnClick = BSortByCapitalClick
188	188		TabOrder = 3
189	189		end
190	190		object BSortByID: TButton
191	191		Left = 318
192	192		Height = 23
193	193		Top = 234
194	194		Width = 75
195	195		AutoSize = True
196	196		Caption = 'Sort by ID'
197	197		OnClick = BSortByIDClick
198	198		TabOrder = 4
199	199		end
200	200		object dbfSource: TDataSource
201	201		left = 53
202	202		top = 99
203	203		end
204	204		end
205	205		```
206	206
207	207		## See also
208	208
209	209		- [[Lazarus Tdbf Tutorial]]
210	210		- [[Guide for usage of Tdbf component/ru]] (rus)
211	211
212	212		---
213	213		From the Free Pascal wiki, page "Example: TDbf (creating table and indexes, selecting of index)", as it stood on 2020-02-14 after a change by Trev, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).
214	214		Category: Databases
215	215		Category: Examples

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