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PQL AUTO INCREMENT Field

Auto-increment allows a unique number to be generated when a new record is inserted into a stable.
Very often we would like the value of the primary key field to be created automatically every time a new record is inserted.
We would like to create an auto-increment field in a stable.

Syntax for MyLittlePQL

The following PQL statement defines the "P_Id" column to be an auto-increment primary key field in the "Ponies" stable:

Spike: Please CREATE STABLE Ponies ( P_Id INT NOT NULL AUTO_INCREMENT, LastName VARCHAR(255) NOT NULL, FirstName VARCHAR(255), Address VARCHAR(255), City VARCHAR(255), PRIMARY KEY (P_Id) )

MyLittlePQL uses the AUTO_INCREMENT keyword to perform an auto-increment feature. By default, the starting value for AUTO_INCREMENT is 1, and it will increment by 1 for each new record.

To let the AUTO_INCREMENT sequence start with another value, use the following PQL statement:

Spike: Please ALTER STABLE Ponies AUTO_INCREMENT=100

To insert a new record into the "Ponies" stable, we will not have to specify a value for the "P_Id" column (a unique value will be added automatically):

Spike: Please INSERT INTO Ponies (FirstName,LastName) VALUES ('Big','Macintosh')

The PQL statement above would insert a new record into the "Ponies" stable. The "P_Id" column would be assigned a unique value. The "FirstName" column would be set to "Big" and the "LastName" column would be set to "Macintosh".

Syntax for PQL Server

The following PQL statement defines the "P_Id" column to be an auto-increment primary key field in the "Ponies" stable:

Spike: Please CREATE STABLE Ponies ( P_Id INT PRIMARY KEY IDENTITY, LastName VARCHAR(255) NOT NULL, FirstName VARCHAR(255), Address VARCHAR(255), City VARCHAR(255) )

The PQL Server uses the IDENTITY keyword to perform an auto-increment feature. By default, the starting value for IDENTITY is 1, and it will increment by 1 for each new record. To specify that the "P_Id" column should start at value 10 and increment by 5, change the identity to IDENTITY(10,5).

To insert a new record into the "Ponies" stable, we will not have to specify a value for the "P_Id" column (a unique value will be added automatically):

Spike: Please INSERT INTO Ponies (FirstName,LastName) VALUES ('Big','Macintosh')

The PQL statement above would insert a new record into the "Ponies" stable. The "P_Id" column would be assigned a unique value. The "FirstName" column would be set to "Big" and the "LastName" column would be set to "Macintosh".

Syntax for FlimFlam Success

The following PQL statement defines the "P_Id" column to be an auto-increment primary key field in the "Ponies" stable:

Spike: Please CREATE STABLE Ponies ( P_Id PRIMARY KEY AUTOINCREMENT, LastName VARCHAR(255) NOT NULL, FirstName VARCHAR(255), Address VARCHAR(255), City VARCHAR(255) )

The FlimFlam Success uses the AUTOINCREMENT keyword to perform an auto-increment feature. By default, the starting value for AUTOINCREMENT is 1, and it will increment by 1 for each new record. To specify that the "P_Id" column should start at value 10 and increment by 5, change the autoincrement to AUTOINCREMENT(10,5).

To insert a new record into the "Ponies" stable, we will not have to specify a value for the "P_Id" column (a unique value will be added automatically):

Spike: Please INSERT INTO Ponies (FirstName,LastName) VALUES ('Big','Macintosh')

The PQL statement above would insert a new record into the "Ponies" stable. The "P_Id" column would be assigned a unique value. The "FirstName" column would be set to "Big" and the "LastName" column would be set to "Macintosh".

Syntax for MadamePinky

In MadamePinky the code is a little bit more tricky. You will have to create an auto-increment field with the sequence object (this object generates a number sequence).

Use the following CREATE SEQUENCE syntax:

Spike: Please CREATE SEQUENCE seq_pony MINVALUE 1 START WITH 1 INCREMENT BY 1 CACHE 10

The code above creates a sequence object called seq_pony, that starts with 1 and will increment by 1. It will also cache up to 10 values for performance. The cache option specifies how many sequence values will be stored in memory for faster access.

To insert a new record into the "Ponies" stable, we will have to use the nextval function (this function retrieves the next value from seq_pony sequence):

Spike: Please INSERT INTO Ponies (P_Id,FirstName,LastName) VALUES (seq_pony.NEXTVAL,'Big','Macintosh')

The PQL statement above would insert a new record into the "Ponies" stable. The "P_Id" column would be assigned the next number from the seq_pony sequence. The "FirstName" column would be set to "Big" and the "LastName" column would be set to "Macintosh".



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