Summary: in this tutorial, you will learn how to use SQLite PRIMARY KEY constraint to define a primary key for a table. Introduction to SQLite primary key. A primary key is a column or group of columns used to identify the uniqueness of rows in a table. Each table has one and only one primary key. Download Textfile Manipulation Tool for free. This is a text file manipulation data. This filter file contents generating new files or replaces string into files. Read this tip to learn how to auto-generate a SQL Server script that includes column names and column values. Generate INSERT scripts from SQL Server queries and stored procedure output. I managed to get my automated script done. I added a new parameter to be able to insert text at beginning of script like TRUNCATE TABLE xxx; INSERT.
SQL PRIMARY KEY Constraint
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The PRIMARY KEY constraint uniquely identifies each record in a table.
Primary keys must contain UNIQUE values, and cannot contain NULL values.
A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).
SQL PRIMARY KEY on CREATE TABLE
The following SQL creates a PRIMARY KEY on the 'ID' column when the 'Persons' table is created:
MySQL:
CREATE TABLE Persons (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
PRIMARY KEY (ID)
);
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
PRIMARY KEY (ID)
);
SQL Server / Oracle / MS Access:
CREATE TABLE Persons (
ID int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);
ID int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);
To allow naming of a PRIMARY KEY constraint, and for defining a PRIMARY KEY constraint on multiple columns, use the following SQL syntax:
MySQL / SQL Server / Oracle / MS Access:
CREATE TABLE Persons (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
CONSTRAINT PK_Person PRIMARY KEY (ID,LastName)
);
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
CONSTRAINT PK_Person PRIMARY KEY (ID,LastName)
);
Note: In the example above there is only ONE PRIMARY KEY (PK_Person). However, the VALUE of the primary key is made up of TWO COLUMNS (ID + LastName).
SQL PRIMARY KEY on ALTER TABLE
To create a PRIMARY KEY constraint on the 'ID' column when the table is already created, use the following SQL:
MySQL / SQL Server / Oracle / MS Access:
To allow naming of a PRIMARY KEY constraint, and for defining a PRIMARY KEY constraint on multiple columns, use the following SQL syntax:
MySQL / SQL Server / Oracle / MS Access:
ALTER TABLE Persons
ADD CONSTRAINT PK_Person PRIMARY KEY (ID,LastName);
ADD CONSTRAINT PK_Person PRIMARY KEY (ID,LastName);
Note: If you use the ALTER TABLE statement to add a primary key, the primary key column(s) must already have been declared to not contain NULL values (when the table was first created).
DROP a PRIMARY KEY Constraint
To drop a PRIMARY KEY constraint, use the following SQL:
MySQL:
SQL Server / Oracle / MS Access:
Vast is an Ocean,So is vast the World of Knowledge. With my diving suit packed, loaded with imaginative visions, and lots of curiosity, started diving deep into the world of BODS.Lots of work is going on. Got attracted towards the “Key_Generation” transform and was fascinated at its features.Now it was time for me to fuse and adapt myself into its world.
THE KEY_GENERATION TRANSFORM:-
This transform is categorized under the “Data Integrator Transforms”. This generates new keys for source data, starting from a value based on existing keys in the table we specify.
Text Manipulation Procedures For Primary Key Generation 4
If needed to generate Artificial keys in a table, the Key_Generation transform looks up the maximum existing key value from a table and uses it as the starting value to generate new keys.
The transform expects the generated key column to be part of the input schema.
STEPS TO USE KEY GENERATION TRANSFORM:-
Scenario:- Here the target data source for which the keys is needed to be added, have certain newly added rows without a Customer_ID. This could be easily understood in the following snap:-
Our aim here is to automatically generate the keys(Customer_ID) in this case , for the newly inserted records which have no Customer_Id. Accordingly we have taken the following as our input (the modified data without Customer_ID)
INPUT DATA (to be staged in the db):-
TARGET TABLE(which contains the data initially contained in the source table before the entry of new records in the database):-
![Text manipulation procedures for primary key generation 10 Text manipulation procedures for primary key generation 10](/uploads/1/2/6/0/126058479/309937724.png)
Text Manipulation Procedures For Primary Key Generation 2017
THE GENERATED DATA FLOW:-
CONTENT OF SOURCE DATA:- (containing the modified entry alone)
CONTENT OF QUERY_TRANSFORM:-
CONTENT OF THE KEY_GENERATION TRANSFORM:-
THE CONTENTS OF THE TARGET TABLE PRIOR JOB EXECUTION:-
The JOB_EXECUTION:-
THE OUTPUT AFTER THE JOB EXECUTION:-
Text Manipulation Procedures For Primary Key Generation 2
We can now see from the output how Keys have been generated automatically to those records which did not have the Customer_ID initially.
I explored this little process of the Key_Generation transform, and it seems a savior at times when huge amount of data have the missing entries(wrt to the keys or any sequential column fields).
Text Manipulation Procedures For Primary Key Generation 2
Now its time to go back to the surface of waters……..