#SERIAL SERIAL#

Keygenguru is a great site for finding all serial keys. Name VARCHAR (90 ) ) AUTO_INCREMENT = 1 - start value Some softwares that are essential for a task but are too expensive to buy can be used with a serial key. There is the table option AUTO_INCREMENT that allows you to define the start value, but you cannot define the increment, it is always 1: MySQL supports AUTO_INCREMENT column option that allows you to automatically generate IDs. SQL Server supports IDENTITY property and allows you to specify the initial and increment values: Note that a trigger is required as Oracle does not allow using NEXTVAL in DEFAULT clause for a column. Oracle does not support SERIAL (auto-increment, identity) columns, but this functionality can be implemented using a sequence and a trigger:ĬREATE SEQUENCE teams_id_seq START WITH 1 INCREMENT BY 1 If you remove rows from a table, you can insert removed IDs explicitly, it will not have any effect on the sequence generator. Continue, now it will use ID 9 INSERT INTO teams (name ) VALUES ( 'Newcastle United' ) ERROR: duplicate key value violates unique constraint 'teams_id_key' - DETAIL: Key (id)=(8) already exists. Will try to assign ID 8 that already inserted INSERT INTO teams (name ) VALUES ( 'Some team' ) You can get an error if there is an UNIQUE constraint, or duplicate IDs can be inserted:

#SERIAL GENERATOR#

Note that the sequence generator may have conflicts with IDs that were already inserted using explicit values. Continue using ID generator INSERT INTO teams (name ) VALUES ( 'Liverpool' ) - ID 7 is assigned Insert ID 8 explicitly INSERT INTO teams VALUES ( 8, 'Everton' ) If you insert an ID value explicitly, it has no effect on the sequence generator, and its next value remains unchanged and will be used when you insert subsequent rows: SERIAL - Specify Initial Value and Increment ERROR: null value in column 'id' violates not-null constraint INSERT INTO teams VALUES ( 0, 'Reserved' ) INSERT INTO teams VALUES ( NULL, 'Some team' ) In MySQL these 2 values force ID generation, but this is not applied to PostgerSQL: Note that you cannot insert NULL, but can insert 0. Specify DEFAULT INSERT INTO teams VALUES ( DEFAULT, 'Manchester City' ) Omit serial column INSERT INTO teams (name ) VALUES ( 'Aston Villa' ) To generate a ID value, you can omit the SERIAL column in INSERT statement, or specify DEFAULT keyword: If you need a SERIAL column to be unique, you have to specify UNIQUE or PRIMARY KEY explicitly. Id INT NOT NULL DEFAULT NEXTVAL ( 'teams_id_seq' ) , is equivalent to CREATE SEQUENCE teams_id_seq When you define a SERIAL column, PostgreSQL automatically changes column to NOT NULL, creates a sequence tablename_serialcol_seq and DEFAULT NEXTVAL to select ID values from the sequence only if they are not supplied in INSERT statement:

Serial