I want to make a not-null non-auto-inc integer my primary key, but I am unable to do so in design time with Firedac. There is no parameter for the TIntegerfield that allows me to make it primary. There is also no parameter of the TFDTable where I can choose the primary field out of all available fields.
I get that it may be possible doing it in code & combining it with my design time table but that beats the whole purpose of doing it all in design time.
Earlier I did have a auto-inc ID in my table, and this was automatically set to primary key. I deleted this field now because I need another integer to be the primary.
Also I can't find information about the primary key & TFDTable on the official Embacadero website.
It's best to experiment with this using a new table in your database and a minimal new Delphi project.
Update: See below for database DDL and Form's DFM.
You need to have your ID field marked as a primary key in your database.
After you've added an FDConnection and an FDTable to your project, select the FDTable's TableName from the drop down list. Then, click in the FDTable's IndexName field and you should find an automatically-named index on the table's Primary Key. Just select it so that the IndexName takes its value. That's all there is to it.
For the table created using the DDL below, the IndexName property of the FDTable appears as sqlite_autoindex_test_1
If you then dbl-click the FDTable and use the pop-up Fields editor to set up persistent fields on the FDTable and then select your ID field, you should find that if you examine its ProviderFlags, they should include pfInKey, which is what tells FireDAC to use the field as the table's primary key when generating the SQL to update it, do inserts, etc.
You should find that the ID field's Required field is autmatically set to True, btw.
If you want to supply the ID Field's value yourself when adding a new record, use the table's OnNewRecord to generate the ID value an assign it to the field.
DDL for test Sqlite database
create table test(
id int not null primary key,
AName nchar(12)
)
Project DFM extract
object Form2: TForm2
object DBGrid1: TDBGrid
DataSource = DataSource1
end
object DBNavigator1: TDBNavigator
DataSource = DataSource1
end
object FDConnection1: TFDConnection
Params.Strings = (
'Database=D:\aaad7\sqlite\MADB1.sqlite'
'DriverID=SQLite')
Connected = True
LoginPrompt = False
end
object DataSource1: TDataSource
DataSet = FDTable1
end
object FDTable1: TFDTable
IndexName = 'sqlite_autoindex_test_1'
Connection = FDConnection1
UpdateOptions.UpdateTableName = 'test'
TableName = 'test'
object FDTable1id: TIntegerField
FieldName = 'id'
Origin = 'id'
ProviderFlags = [pfInUpdate, pfInWhere, pfInKey]
Required = True
end
object FDTable1AName: TWideStringField
FieldName = 'AName'
Origin = 'AName'
FixedChar = True
Size = 12
end
end
end
Related
I create a table in which there is an element, parentId, that is linked via a FOREIGN KEY to another uniqueId of the same table:
CREATE TABLE folders (
uniqueId INTEGER PRIMARY KEY,
name TEXT NOT NULL,
parentId INTEGER DEFAULT NULL,
created TEXT DEFAULT (datetime('now', 'localtime')),
updated TEXT DEFAULT (datetime('now', 'localtime')),
FOREIGN KEY (parentId)
REFERENCES folders (uniqueId)
ON DELETE SET DEFAULT
);
I also have a TRIGGER that will set the updated field to the current time upon modifying the parentId field.
CREATE TRIGGER folder_parentId_is_changed
AFTER UPDATE ON folders
WHEN new.parentId <> old.parentId
BEGIN
UPDATE folders
SET updated = datetime('now','localtime')
WHERE parentId = new.parentId;
END;
If the parentId has a non-NULL value, and I change the parentId to another non-NULL value, the TRIGGER works as I desire, and the updated field is set to current time.
However, TRIGGER does not capture changes to or from NULL. That is, if the parentId is currently NULL and I change it so that parentId == 5, the TRIGGER will not update my update field.
Thank you in advance
There are 2 problems with your query.
First, the condition:
WHEN new.parentId <> old.parentId
will not work if either of new.parentId or old.parentId is null, because the result of the comparison with the operator <> will be null and will never be true.
So you must use IS NOT instead of <>, which will work for nulls and not nulls.
Also, the condition in the UPDATE statement:
WHERE parentId = new.parentId
is wrong, because it may return all the rows where parentId is equal to new.parentId, or none if new.parentId is null.
Instead you should set a condition that returns the row that you want to update based on the column uniqueId which is the primary key of the table and will return only the row that is updated:
CREATE TRIGGER folder_parentId_is_changed
AFTER UPDATE ON folders
WHEN NEW.parentId IS NOT OLD.parentId
BEGIN
UPDATE folders
SET updated = DATETIME('now', 'localtime')
WHERE uniqueId = OLD.uniqueId;
END;
I am working on SQLite. I want to create a table namely user_role with two column role_id and role_name. And there is an another table namely default that contain role_name and default_val.
I want to set Default value of role_id in the time of creating the table user_role and the Default value have to be retrieved from the table default.
I am new to SQLite and have to idea about the way to doing such recursive query. Please help.
The documentation says:
An explicit DEFAULT clause may specify that the default value is NULL, a string constant, a blob constant, a signed-number, or any constant expression enclosed in parentheses.
You would need to use a subquery, which is not allowed.
However, you could use a trigger that sets the ID if none was specified:
CREATE TRIGGER user_role_id_default
AFTER INSERT ON user_role
FOR EACH ROW
WHEN NEW.role_id IS NULL
BEGIN
UPDATE user_role
SET role_id = (SELECT default_val
FROM "default"
WHERE role_name = NEW.role_name)
WHERE rowid = NEW.rowid;
END;
Im using Simple.Data to insert data into an Sqlite database. I read on the wiki that Insert returns the inserted data. I need to get the latest rowID (identity). But I get Null instead.
Using the Stable version from NuGet.
var db = Database.OpenFile("Database.db");
var x = db.Scan.Insert(Name:"Test", Description:"test", CreationDate:DateTime.Now, DocumentDate:DateTime.Now, ModifiedDate:DateTime.Now);
DB schema:
CREATE TABLE Scan (
ID INTEGER PRIMARY KEY,
Name NVARCHAR( 50 ) NOT NULL,
Description TEXT,
CreationDate DATETIME NOT NULL,
DocumentDate DATETIME NOT NULL,
ModifiedDate DATETIME NOT NULL
);
Does this even work for SQLite? If not whats the best way to retrieve the rowID of the inserted record?
Had the same "issue".
The problem lies within your schema.
You have to add identity to your primary key column:
ID INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
Then you get back the row and you can i.e. create a new object with it:
var x = db.Scan.Insert(Name:"Test", Description:"test", CreationDate:DateTime.Now, DocumentDate:DateTime.Now, ModifiedDate:DateTime.Now);
return new Scan { ID = (int)x.ID, Name = x.Name, ... }
From the Wiki:
If you have an IDENTITY column defined on your table, then the Insert
methods will all return a copy of the record fetched from the
database, so all defaulted values are set. In 0.4, support for other
ways of fetching the inserted row will be added.
I am using asp.net2008 and MY SQL.
I want to auto-generate the value for the field username with the format as
"SISI001", "SISI002",
etc. in SQL whenever the new record is going to inserted.
How can i do it?
What can be the SQL query ?
Thanks.
Add a column with auto increment integer data type
Then get the maximum value of that column in the table using "Max()" function and assign the value to a integer variable (let the variable be 'x').
After that
string userid = "SISI";
x=x+1;
string count = new string('0',6-x.ToString().length);
userid=userid+count+x.ToString();
Use userid as your username
Hope It Helps. Good Luck.
PLAN A>
You need to keep a table (keys) that contains the last numeric ID generated for various entities. This case the entity is "user". So the table will contain two cols viz. entity varchar(100) and lastid int.
You can then have a function written that will receive the entity name and return the incremented ID. Use this ID concatenated with the string component "SISI" to be passed to MySQL for insertion to the database.
Following is the MySQL Table tblkeys:
CREATE TABLE `tblkeys` (
`entity` varchar(100) NOT NULL,
`lastid` int(11) NOT NULL,
PRIMARY KEY (`entity`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
The MySQL Function:
DELIMITER $$
CREATE FUNCTION `getkey`( ps_entity VARCHAR(100)) RETURNS INT(11)
BEGIN
DECLARE ll_lastid INT;
UPDATE tblkeys SET lastid = lastid+1 WHERE tblkeys.entity = ps_entity;
SELECT tblkeys.lastid INTO ll_lastid FROM tblkeys WHERE tblkeys.entity = ps_entity;
RETURN ll_lastid;
END$$
DELIMITER ;
The sample function call:
SELECT getkey('user')
Sample Insert command:
insert into users(username, password) values ('SISI'+getkey('user'), '$password')
Plan B>
This way the ID will be a bit larger but will not require any extra table. Use the following SQL to get a new unique ID:
SELECT ROUND(NOW() + 0)
You can pass it as part of the insert command and concatenate it with the string component of "SISI".
I am not an asp.net developer but i can help you
You can do something like this...
create a sequence in your mysql database as-
CREATE SEQUENCE "Database_name"."SEQUENCE1" MINVALUE 1 MAXVALUE 9999999999999999999999999999 INCREMENT BY 001 START WITH 21 CACHE 20 NOORDER NOCYCLE ;
and then while inserting use this query-----
insert into testing (userName) values(concat('SISI', sequence1.nextval))
may it help you in your doubt...
Try this:
CREATE TABLE Users (
IDs int NOT NULL IDENTITY (1, 1),
USERNAME AS 'SISI' + RIGHT('000000000' + CAST(IDs as varchar(10)), 4), --//getting uniqueness of IDs field
Address varchar(150)
)
(not tested)
The title, while long, pretty much says it all.
What I have is a master table with a bunch of supporting table relations through foreign keys. For a few of the foreign tables, upon attempting to insert a record into the master table where one of the foreign keys doesn't exist, the data would be passed to the foreign table to create the record first, thereby making the constraint valid and passing the key to the created record back to the insert procedure of the master table.
This data comes from a form in String form, but naturally the foreign key will be an int. The process would look something like this:
-- ASP.NET Web Form --
Requestor Name: _____________ (combobox)
Request: _____________ (dropdownlist)
Date: _____________ (datepicker)
This is a super simplified version, but assume we have a master table with the above data, where both names are foreign keys to a People table. The name fields are comboboxes with a populated list of names linking to People. However, if I wanted to enter a person who didn't yet exist in the People table, the procedure should first create the Person, then use the ID from that new record as the foreign key in the Master table containing columns for the above.
I'm using SQL Server and ASP.NET with VB.NET codebehind. I've been scratching my head over this one for awhile, how to pass data (in different forms such as a foreign key or string) between the web server and DB server, as well as where to validate / transform the data.
It seems the entered name will be passed as an ID if the foreign key exists, and a String if not.
This is my most perplexing problem so far, and no idea where else to look. I've read up on Scott Mitchell's site and others.
MY SOLUTION (?)
The best I can come up with is to pass the user input from the user as a string and convert it to int in the T-SQL procedure. If the value was selected from the drop down, it should match precisely with a valid foreign key. If it doesn't match, then create a new Person and return a foreign key. Is this best practice?
This seems complicated because it is. You have to get your hands dirty. If you need a relational database with ACID support, there's no auto-magical way of getting around it.
Relational databases 101: The primary key must exist before the foreign key can be populated (This is the reason why data warehouse developers populate the dimension table before the fact table). You'll have to design the logic to validate that the primary key exists, insert and get the key if not, and just get the key if exists.
Here's my implementation. I don't know if it's the best, but it worked well for me. Basically I take the values from the controls; in the case of the combobox I need the values from both the TextBox and DropDownList. I then pass those values to the following function in my codebehind:
'This method determines if the name selected already exists in the selection
' options and if so assigns the corresponding ID value to an object variable,
' if not it assigns the value of the `TextBox` to the variable.
Protected Function _ValidateValues(ByRef ddl As DropDownList, ByRef cb As TextBox) As Object
'Ensures the selected value is valid by checking against the entered value in the textbox
If Not String.IsNullOrEmpty(cb.Text) Then
If ddl.Items.Count > 0 Then
If StrComp(cb.Text, ddl.SelectedItem.ToString) = 0 Then
Return ddl.Items.Item(ddl.SelectedIndex).Value 'Returns the index of dropdown selected name
End If
End If
'This counts the capital letters in the entered value and if fewer than 2
' auto capitalizes the first letters. This also allows for project code
' names such as "DOORS" and people names such as "Allen McPherson" etc.
' Be careful though because if "allen McPherson" is entered, it will NOT
' be corrected, though it displays correctly.
Dim rg As New Regex("[A-Z]")
Dim mc As MatchCollection = rg.Matches(cb.Text)
If mc.Count < 2 Then
Return StrConv(cb.Text, VbStrConv.ProperCase)
Else : Return cb.Text
End If
End If
'Returns a SQL DB NULL object if an empty string is submitted
Return DBNull.Value
End Function
Then my stored procedure handles the values something like so...
(Forgive me if I neglected to replace some of the values. I tried to catch them all.)
CREATE PROCEDURE spInsertUser
#User nvarchar(50) = NULL,
#Role nvarchar(50) = NULL,
#RecordID int output -- Returned Value
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
-- CHECK IF USER EXISTS
-- Insert new record to Users table if the requested user doesn't exist
-- Needed to ensure that the foreign keys are relevant
IF #User = '' OR #User IS NULL BEGIN SET #User = NULL SET #RecordID = NULL END --Ensures that an empty string cannot be submitted, thereby causing an error.
ELSE BEGIN
declare #forename varchar(50), #surname varchar(50)
declare #uid table (ID int)
declare #users table (ID smallint, Name nvarchar(50))
insert into #users
select ID, Name from Users
--If the value can be converted into an int, we need go no further.
BEGIN TRY SET #RecordID = CONVERT(smallint, #User) END TRY
BEGIN CATCH
BEGIN TRY --Otherwise, attempt to parse the name
Set #User = LTRIM(RTRIM(#User)) --Trim the extra space at the beginning and end. This ensures the following "IF" test will evaluate properly.
IF NOT CHARINDEX(' ', #User) > LEN(#User) AND CHARINDEX(' ', #User) > 0 BEGIN -- Confirm First & Last Name exist
Set #forename = RTRIM(LEFT(#User, CHARINDEX(' ',#User,0)-1))
Set #surname = LTRIM(RIGHT(#User, LEN(#User) - CHARINDEX(' ',#User,0)))
Set #User = #forename + ' ' + #surname --Ensure that there is a valid First & Last name
IF LEN(#forename) > 1 AND LEN(#surname) > 1 BEGIN -- Confirm First & Last Name exist
--First ensure that the User doesn't already exist, and if
-- so use their ID, if not insert the new User.
IF NOT EXISTS (select Name from #users where Name like #User) BEGIN --Check if the user already exists
INSERT INTO Users (Name, Forename, Surname) OUTPUT INSERTED.ID INTO #uid Values (#User, -- If not, insert them
#forename, #surname) --Nicely manicured first, last, and full names
SET #RecordID = CONVERT(smallint, (select MAX(ID) from #uid)) END -- Now set the Role to the ID of the new user
ELSE BEGIN --Otherwise if the user already exists, set the Role to the ID of that user
SET #RecordID = (select ID from #users where Name like #User) END
IF NOT EXISTS (select * from rUsersInRoles where UserID = #RecordID) BEGIN
--Do some string manipulation to increase the chances of matching the role
SET #Role = REPLACE(REPLACE(REPLACE(LTRIM(RTRIM(#Role)), ' ', '%'), '.', '%'), '#', '%') --Trims & replaces spaces & periods with wildcards
INSERT INTO rUsersInRoles (UserID, UserRoleID) VALUES
(#RecordID, (select top 1 ID from rUserRoles where Role like #Role)) END
END
END
END TRY
BEGIN CATCH END CATCH
END CATCH
END
END
This stored procedure deals with the case of User Roles as well. If the more simple case of Users only is needed, simply remove the clauses dealing with the checking and insertion of User Roles. :)