Firebird: what changed

Revision 1 to 2. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		This is a guide about using Firebird database in Lazarus/FPC, using Firebird with SQLDB (the FPC/Lazarus built-in database library). Other access methods are described in [[Other Firebird libraries]].
2	2
3	3		## Overview
4	4
5	5		Firebird is an open source, free database server that has been in use and developed for decades (it developed out of the Interbase 6 database that was open sourced by Borland). It includes rich support for SQL statements (e.g. INSERT...RETURNING), stored procedures, triggers, etc. You can write compiled UDFs (User-Defined Functions) libraries for the server in FreePascal if you want to extend the already extensive function list of Firebird.
6	6
7	7		The database requires very little manual DBA work once it is set up, making it ideal for small business use or embedded use. It can grow to terabyte scale given proper tuning, although PostgreSQL may be a better choice for such large environments.
8	8
9	9		Firebird offers both embedded (file-based) and client-server database - usable without having to change a single line of code in FPC/Lazarus. If used as an embedded database, it offers a richer SQL support than [[SQLite]] as well as seamless migration to a client-server database, although SQLite is a quite capable embedded database itself.
10	10
11	11		The latest stable version, Firebird 2.5, runs on Windows (32- and 64-bit), various Linux versions (32- and 64-bit), Solaris (Sparc and Intel), HP-UX (PA-Risc) and OSX.
12	12
13	13		It is being ported to Android at the moment; it is not available on Windows CE/Windows Mobile.
14	14
15	15		Support for Firebird in FPC's SQLDB is quite good, comparable to the level of [[postgres\|PostgreSQL]] support.
16	16
17	17		## Documentation
18	18
19	19		Official documentation is included in FPC 2.6.2+: [SQLDB documentation for IBConnection](http://www.freepascal.org/docs-html/fcl/ibconnection/index.html)
20	20
21	21		## Client/server and embedded installation
22	22
23	23		Firebird can run in client/server and embedded mode.
24	24
25	25		Client/Server means that you have a physical Firebird server somewhere: either on your local machine or another machine reachable over your network. Connections to the server go through TCP/IP; when specifying the connection, the hostname contains a name or IP address. The Firebird DLL you need for this is fbclient.dll (along with its support files).
26	26
27	27		Embedded Firebird means that your application loads the Firebird DLLs to access a Firebird database on the local machine. When specifying the connection, the hostname is always empty. The Firebird DLL you need for this is fbembed.dll (along with its support files). See [[Firebird embedded\|the wiki page on Firebird embedded]] for more details.
28	28
29	29		Note that fbembed.dll can be used both for client/server and embedded use, so installing only this dll may be a smart thing to do.
30	30
31	31		### Windows
32	32
33	33		Win64: please see warning [[Windows Programming Tips\|here]] on not using certain FPC/Lazarus Win64 versions.
34	34
35	35		On Windows: (this applies to all SQLDB database drivers) you must have fbclient.dll (or fbembed.dll) and its support dlls installed in:
36	36
37	37		- the project directory and the executable output directory/the application directory (e.g. lib/something under your project directory)
38	38		- or a directory in your PATH (not your system directory)
39	39		- If you want to use the system directory, please use the official installer and tick "copy fbclient to system directory"
40	40
41	41		As with all (database) DLLs, the bitness of the DLL must match your application: use a 32 bit library for a 32 bit compiled program and a 64 bit library for a 64 bit program.
42	42
43	43		### Unix/Linux/macOS
44	44
45	45		On FreeBSD/Linux/macOS, the Firebird client library should be installed (e.g. by your package manager; install the regular package and the -dev package), or they should be placed in the library search path.
46	46
47	47		FPC searches for the most common library names (e.g. libfbclient.so.2.5, libgds.so, and libfbembed.so.2.5; please check ibase60.inc if your version is different). If you want to, you can explicitly specify the library name. There are 2 ways for this:
48	48
49	49		- use the [[TSQLDBLibraryLoader]] component from sqldblib (FPC 2.7.1). Works for all SQLDB connector components.
50	50		- call
51	51		``` pascal
52	52		function InitialiseIBase60(Const LibraryName : AnsiString) : integer;
53	53		```
54	54
55	55		with the correct library name (you may need to use unit ibase60dyn for this).
56	56
57	57		## Connection examples
58	58
59	59		Example for client/server:
60	60
61	61		`Hostname: 192.168.1.1`\
62	62		`* The database is on the server with IP address 192.168.1.1. `\
63	63		`DatabaseName: /interdata/example.fdb `\
64	64		`* The name of the database file is "example.fdb" in the /interdata directory of the server (the machine with IP address 192.168.1.1).`\
65	65		`Username: SYSDBA`\
66	66		`Password: masterkey`
67	67
68	68		Another example for client/server:
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70	70		`Hostname: dbhost`\
71	71		`* The database is on the server with the host name dbhost`\
72	72		`DatabaseName: F:\Program Files\firebird\examples\employee.fdb `\
73	73		`* The name of the database file is "employee.fdb" in the Program Files\firebird\examples directory on the F: drive of dbhost.`\
74	74		`Username: SYSDBA`\
75	75		`Password: masterkey`
76	76
77	77		An embedded example:
78	78
79	79		`Hostname: <empty string>`\
80	80		`* Leaving the hostname empty selects embedded use.`\
81	81		`DatabaseName: test.fdb`\
82	82		`* The database file is "test.fdb" in the directory where the application runs (make sure fbembed.dll is in the application executable directory)`\
83	83		`Username: SYSDBA`\
84	84		`* On embedded, you do have to specify a username...`\
85	85		`Password: <empty string>`\
86	86		`* ... but it doesn't matter what password you give.`
87	87
88	88		## Troubleshooting client/server access issues
89	89
90	90		Make sure you started the Interbase/Firebird server on the server IP/hostname you specified. You can test connectivity by telnetting to the machine. Firebird usually listens on port 3050:
91	91
92	92		``` bash
93	93		telnet 192.168.1.1 3050
94	94		```
95	95
96	96		You should see something, maybe just a blank screen, but you can type something. This means you can send data to the Firebird database.
97	97
98	98		For further information, please see the Firebird documentation.
99	99
100	100		## Monitoring Events
101	101
102	102		FPC/Lazarus comes with a component to monitor events coming from Firebird databases; see [[TFBEventMonitor]].
103	103
104	104		## Creating objects programmatically
105	105
106	106		While you can use tools such as Flamerobin to create tables etc, you can also create these programmatically/dynamically, which could be handy when you want your programs to update existing database schemas to a new schema.
107	107
108	108		You can use e.g. TSQLQuery.ExecSQL to perform this task:
109	109
110	110		``` pascal
111	111		Query.ExecSQL('CREATE TABLE TEST(ID INTEGER NOT NULL, TESTNAME VARCHAR(800))');
112	112		// You need to commit the transaction after DDL before any DML - SELECT, INSERT etc statements.
113	113		// Otherwise the SQL won't see the created objects
114	114		```
115	115
116	116		To do this, use the TSQLScript object - see [[TSQLScript]].
117	117
118	118		## Database Administration
119	119
120	120		FPC/Lazarus has a component for database adminstration; see [[TFBAdmin]]
121	121
122	122		## Common problems and solutions
123	123
124	124		Sometimes using Firebird in Lazarus seems to be tricky. Please find solutions below.
125	125
126	126		### Attempted update of read-only column / COMPUTED BY fields
127	127
128	128		If you have COMPUTED BY fields (server-side calculated fields) in your Firebird table, SQLDB will not pick up that these are read only fields (for performance reasons).
129	129
130	130		In this case, auto-generated INSERTSQL,UPDATESQL statements can lead to error messages like "attempted update of read-only column". The solution is to manually specify that the field in question may not be updated after setting the TSQLQuery's SQL property, something like:
131	131
132	132		``` pascal
133	133		// Disable updating this field or searching for changed values as user cannot change it
134	134		sqlquery1.fieldbyname('full_name').ProviderFlags:=[];
135	135		```
136	136
137	137		### Bigint: lost precision
138	138
139	139		If you use the bigint datatype (64 bit signed integer) in Firebird, please use .AsLargeInt instead of .AsInteger for parameters:
140	140
141	141		``` pascal
142	142		// Assuming ID is bigint here
143	143		sqlquery1.sql.text := 'insert into ADDRESS (ID) values (:ID)';
144	144		// Use this:
145	145		sqlquery1.params.parambyname('ID').aslargeint := <some qword or 64 bit integer variable>;
146	146		// Do not use this:
147	147		//sqlquery1.params.parambyname('ID').asinteger := <some qword or 64 bit integer variable>;
148	148		...
149	149		```
150	150
151	151		... otherwise you might get errors like duplicate PK (primary key) - if using the bigint as a primary key.
152	152
153	153		### Boolean data types
154	154
155	155		Firebird versions below 3.0 do not support boolean data types.
156	156
157	157		At least on FPC trunk (2.7.1) this datatype can be emulated:
158	158
159	159		Use a DOMAIN that uses a SMALLINT type (other integer types may work as well - please test and adjust text):
160	160
161	161		``` SQL
162	162		CREATE DOMAIN "BOOLEAN"
163	163		AS SMALLINT
164	164		CHECK (VALUE IS NULL OR VALUE IN (-1,0,1))
165	165		/* -1 used for compatibility with FPC SQLDB; 1 is used by many other data access layers */
166	166		;
167	167		```
168	168
169	169		Let your field/column use this domain type e.g.
170	170
171	171		``` SQL
172	172		CREATE TABLE MYTABLE
173	173		(
174	174		...
175	175		MYBOOLEANCOLUMN "BOOLEAN",
176	176		);
177	177		```
178	178
179	179		- Now you can use .AsBoolean for assigning field values etc
180	180
181	181		To do: verify this works with Lazarus grids etc as well.
182	182
183	183		### INSERT INTO...RETURNING problems/Cursor is not open
184	184
185	185		= If you try to select SQL (e.g. Query.Open) with SQL like this:
186	186
187	187		``` SQL
188	188		INSERT INTO PEOPLE (NICKNAME) VALUES ('Superman') RETURNING ID
189	189		```
190	190
191	191		and get something like this error:
192	192
193	193		```dos
194	194		Database error: : Fetch :
195	195		-Dynamic SQL Error
196	196		-SQL error code = -504
197	197		-Invalid cursor reference
198	198		-Cursor is not open(error code: 335544569)
199	199		```
200	200
201	201		while running FPC 2.6.0 (which is supplied with Lazarus 1.0) or lower, then you probably ran into an FPC SQLDB parser bug.
202	202
203	203		SQLDB thinks the statement you're running is a normal INSERT statement, which doesn't return data. Obviously, it should return data. Newer FPC code has fixes for this.
204	204
205	205		If you're using generators/sequences for your primary keys (like many do), a workaround is to first get the next sequence number:
206	206
207	207		``` SQL
208	208		SELECT NEXT VALUE FOR GEN_PEOPLEID FROM RDB$DATABASE /* If your generator name is GEN_PEOPLEID */
209	209		```
210	210
211	211		then use that to do a regular INSERT. see [FAQ entry](http://www.firebirdfaq.org/faq111/%7CFirebird)
212	212
213	213		### Locate does not seem to work
214	214
215	215		Source: [Issue \##21988](https://bugs.freepascal.org/view.php?id=#21988)
216	216
217	217		When running locate on UTF8 (or presumably other multibyte character sets) CHAR fields, locate may not find your record.
218	218
219	219		The problem is related mostly to UTF8 charset used and how Firebird reports column length. In case of UTF8 Firebird reports the maximum column length (in bytes) as 4"character length". So if you have a column defined as char(8), Firebird reports 48=32.
220	220
221	221		Values are right-padded to this length 32. When locating say '57200001' there is no match because the field actually stores '57200001 ........................' (with trailing spaces represented by dots here).
222	222
223	223		Workaround: rewrite your select query:
224	224
225	225		``` sql
226	226		SELECT substring(THEFIELD from 1 for 8) AS THEFIELD ...
227	227		```
228	228
229	229		`or`
230	230
231	231		``` sql
232	232		SELECT cast(THEFIELD as varchar(8)) as THEFIELD ...
233	233		```
234	234
235	235		or use VARCHAR fields.
236	236
237	237		Note: this problem may occur for other databases as well depending on their reporting of field length.
238	238
239	239		## Advanced transactions
240	240
241	241		Sources for this information/further reading:
242	242
243	243		- [Understanding Firebird Transactions](http://www.ibphoenix.com/resources/documents/how_to/doc_400) very detailed article
244	244		- [Transactions in Firebird](https://ib-aid.com/en/transactions-in-firebird-acid-isolation-levels-deadlocks-and-update-conflicts-resolution/) another very detailed article
245	245		- Interbase 6 API Guide (valid for Firebird+Interbase), page 63 and further
246	246		- [Overview of transaction settings in Interbase](http://conferences.embarcadero.com/article/32280)
247	247		- [Detailed explanation of parameters in Firebird](http://tech.groups.yahoo.com/group/firebird-support/message/58653)
248	248		- [Overview of settings in Firebird](http://fhasovic.blogspot.com/2005/02/transaction-isolation-levels-in.html)
249	249		- [Transaction isolation levels in FIBPlus](http://www.devrace.com/en/fibplus/articles/3292.php)
250	250		- README.set_transaction.txt in Firebird 2.5 documentation folder.
251	251
252	252		### Transaction isolation levels
253	253
254	254		If you want to, you can change the transaction isolation levels by adding a line in the transaction's Parameters property:
255	255
256	256		- `isc_tpb_read_committed`: you see all changes committed by other transactions
257	257		- `isc_tpb_concurrency`: also called Snapshot: you see database as it was when the transaction started. Has more overhead than isc_tpb_read_committed. Better than ANSI Serializable because it has no phantom reads.
258	258		- `isc_tpb_consistency`: also called Table Stability: stable, serializable view of data, but locks tables. Unlikely you will need this
259	259
260	260		Example:
261	261
262	262		``` pascal
263	263		SQLTransaction1.Params.text:='isc_tpb_read_committed';
264	264		```
265	265
266	266		You can also add additional parameters that have an effect on the transaction (taken from the ibconnection.pp source file and [1](http://conferences.embarcadero.com/article/32280)):
267	267
268	268		### Access mode
269	269
270	270		This allow reads only or read/write
271	271
272	272		- `isc_tpb_read`: read permission
273	273		- `isc_tpb_write`: read+write permission
274	274
275	275		### Lock resolution
276	276
277	277		- `isc_tpb_nowait`: if another transaction is editing the record then don't wait
278	278		- `isc_tpb_wait`: if another transaction is editing the record then wait for it to finish. Can mitigate "live locks" in heavy contention ([2](http://tech.groups.yahoo.com/group/firebird-support/message/58653)). See below for timeout value.
279	279
280	280		### Table reservation
281	281
282	282		Deals with locking entire tables.
283	283
284	284		- `isc_tpb_shared`: first specify this, then either lock_read or lock_write for one or more tables. Shared read or write mode for tables.
285	285		- `isc_tpb_protected`: first specify this, then either lock_read or lock_write for one or more tables. Lock on tables; can allow deadlock-free operation at the cost of delayed transactions
286	286		- `isc_tpb_lock_read`: Set a read lock. Specify which table to lock, e.g. isc_tpb_lock_read=CUSTOMERS
287	287		- `isc_tpb_lock_write`: Set a read/write lock. Specify which table to lock, e.g. isc_tpb_lock_read=CUSTOMERS
288	288
289	289		Combinations:
290	290
291	291		- Shared, lock_write: write transactions with concurrency or read committed isolation
292	292
293	293		can update the table. All transactions can read the table
294	294
295	295		- Shared, lock_read: any transaction can read or update
296	296		- Protected, lock_write: Other transactions cannot update the table. Only concurrency and
297	297
298	298		read committed transactions can read the table
299	299
300	300		- Protected, lock_read: Other transactions cannot update the table. Any transaction can
301	301
302	302		read the table
303	303
304	304		### Record versions
305	305
306	306		This setting is apparently only relevant for isc_tpb_read_committed isolation mode for records being modified by other transactions:
307	307
308	308		- `isc_tpb_no_rec_version`: only newest record version is read. Can be useful for batch/bulk insert operations together with isc_tpb_read_committed)
309	309		- `isc_tpb_rec_version`: the latest committed version is read, even when the other transaction has other uncommitted changes note: verify this. More overhead than isc_tpb_no_rec_version
310	310
311	311		### Various options
312	312
313	313		For completeness, some more options appearing in the Firebird/Interbase FPC code. You will likely only ever use isc_tpb_no_auto_undo to speed up batch inserts/edits.
314	314
315	315		- isc_tpb_exclusive (apparently translates to protected in Firebird, see [3](http://tech.groups.yahoo.com/group/firebird-support/message/58653))
316	316		- isc_tpb_verb_time (Related to deferred constraints, which could execute at verb time or commit time. Firebird: not implemented, always use verb time)
317	317		- isc_tpb_commit_time (Related to deferred constraints, which could execute at verb time or commit time. Firebird: not implemented, always use verb time)
318	318		- isc_tpb_ignore_limbo (ignores the records created by transactions in limbo. Limbo transactions are failing two-phase commits in multi-database transactions. Unlikely that you will need this feature)
319	319		- isc_tpb_autocommit (autocommit this transaction: every statement is a separate transaction. Probably specifically for JayBird JDBC driver.)
320	320		- isc_tpb_restart_requests (apparently looks for requests in the connection which had been active in another transaction, unwinds them, and restarts them under the new transaction.)
321	321		- isc_tpb_no_auto_undo (disable transaction-level undo log, handy for getting max throughput when performing a batch update. Has no effect when only reading data.)
322	322		- isc_tpb_lock_timeout (specify number of seconds to wait for lock release, if you use isc_tpb_wait. If this value is reached without lock release, an error is reported.)
323	323
324	324		### Firebird and ISO transactions
325	325
326	326		Firebird transaction do not map 1 to 1 to ISO/ANSI transaction levels. An approximation is:
327	327
328	328		- ISO Read Committed=READ COMMITTED+RECORD_VERSION
329	329		- ISO Read Committed=READ COMMITTED+NO RECORD_VERSION
330	330		- ISO Repeatable Read=SNAPSHOT (also known as CONCURRENCY)
331	331		- ISO Serializable=SNAPSHOT TABLE STABILITY (also known as CONSISTENCY)
332	332
333	333		### Common combinations
334	334
335	335		Default is (probably, will have to check) read committed.
336	336
337	337		#### Batch/bulk insert
338	338
339	339		isc_tpb_read_committed and isc_tpb_no_rec_version could be a good combination: it allows other transactions to function while the batch is going on.
340	340
341	341		#### Read only transaction
342	342
343	343		If you want to only have read access to the database, you can do so by setting these transaction parameters:
344	344
345	345		- `isc_tpb_read`
346	346		- `isc_tpb_read_committed`
347	347		- `isc_tpb_rec_version`
348	348		- `nowait`
349	349
350	350		This combination will not block garbage collection, which is a good thing. Source: [4](http://tech.groups.yahoo.com/group/firebird-support/message/118748)
351	351
352	352		Note: the [Firebird FAQ](http://www.firebirdfaq.org/faq164/) indicates you will need write access to the database file even if you only read from it, unless you set the database read-only flag (e.g. using gfix).
353	353
354	354		## Links and more information
355	355
356	356		The list below shows links to more information on Firebird and related tools.
357	357
358	358		- [[Firebird embedded\|Using Firebird embedded with FPC/Lazarus]]
359	359
360	360		### Lazarus Firebird samples
361	361
362	362		- Sample Lazarus/Firebird application source code [5](http://lazarus.freepascal.org/index.php/topic,13940.msg73617.html#msg73617)
363	363		- Firebird/SQLDB tutorials:
364	364		- [[SQLdb Tutorial0]]
365	365		- [[SQLdb Tutorial1]]
366	366		- [[SQLdb Tutorial2]]
367	367		- [[SQLdb Tutorial3]]
368	368		- [[SQLdb Tutorial4]]
369	369
370	370		- PP4S tutorials; cover Firebird installation on Windows as well:
371	371		- [Planning a Database](http://www.pp4s.co.uk/main/tu-db-plan.html)
372	372		- [Installing Firebird](http://www.pp4s.co.uk/main/tu-db-installingfirebird01.html)
373	373		- [Creating a Firebird database](http://www.pp4s.co.uk/main/tu-db-firebird-create.html)
374	374		- [Editing a Firebird database](http://www.pp4s.co.uk/main/tu-db-firebird-demo1.html)
375	375		- [Searching a Firebird database](http://www.pp4s.co.uk/main/tu-db-firebird-demo2.html)
376	376		- [Creating and printing a report](http://www.pp4s.co.uk/main/tu-db-firebird-demo3.html)
377	377		- [Creating and using stored procedures](http://www.pp4s.co.uk/main/tu-db-firebird-demo4.html)
378	378
379	379		### Tools
380	380
381	381		- FlameRobin [Flamerobin site](http://www.flamerobin.org/) Open source GUI tool to manage Firebird, available for Linux, Windows and Mac OSX. Highly recommended.
382	382		- Turbobird [Turbobird site](https://github.com/motaz/turbobird) Open source GUI tool to manage Firebird. Written with Lazarus using TIBConnection
383	383		- ibconsole : Tool to manage Firebird an Interbase Databases with a GUI, available for Windows and Linux
384	384		- Lazarus Data Desktop - included in the Lazarus repository (found in the 'tools/lazdatadesktop/' directory)
385	385		- [LazSQLX](http://lazsqlx.wordpress.com/) Multi-database open source database management tool. Written with Lazarus using both SQLDB and Zeos components. Includes support for Firebird.
386	386		- tiSQLEditor - included in the "Support Apps" directory of the [[tiOPF]] repository. It is a tool used to write SQL with some code completion support, can run scripts, execute upgrade scripts for applications from one build to a later build, has various handy copy and paste functions for Object Pascal applications, has many features that are useful to tiOPF (creates Object Pascal code templates from query results, for tiOPF's visitor classes), export query results to CSV etc.
387	387
388	388		### Firebird
389	389
390	390		- The Firebird RDBMS [Firebird site](http://firebirdsql.org/). This site also contains a lot of documentation on Firebird.
391	391		- Firebird FAQ [6](http://firebirdfaq.org/). Handy site that shows e.g. differences with other RDBMS.
392	392		- New site that shows how to use the latest tools and LibreOffice, FPC to be added soon [Firebird](http://www.controlpascal.com/firebird.htm)
393	393
394		-	\
395		-
396	394		---
397	395		From the Free Pascal wiki, page "Firebird", as it stood on 2020-02-16 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).

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