Tag: sequences

The 6 SERIAL Data Types in PostgreSQL

Posted on by Ian

The SERIAL data type in PostgreSQL is a pseudo-type used to create an auto-incrementing sequence of integers for a column. It is commonly used for primary keys, as it eliminates the need to manually assign unique identifiers for each new record. PostgreSQL handles this by automatically creating a sequence object that supplies a unique number each time a new row is inserted.

PostgreSQL provides three SERIAL types, each with two options for usage; which effectively equates to six different types. So basically, we have six options to choose from when creating a SERIAL column.

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6 Ways to Fix “nextval: reached minimum value of sequence” in PostgreSQL

Posted on by Ian

If you’re getting an error that reads something like “nextval: reached minimum value of sequence “sequence1” (-3)” in PostgreSQL, it’s probably because you’re trying to generate a new value from a descending sequence, but the sequence has already reached its minimum value.

We have a number options when it comes to dealing with this issue.

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Fix “MINVALUE (…) must be less than MAXVALUE (…)” When Creating a Sequence in PostgreSQL

Posted on by Ian

If you’re getting an error that reads something like “MINVALUE (1) must be less than MAXVALUE (1)” in PostgreSQL when you’re trying to create a sequence, it’s probably because your sequence’s minimum possible value is higher than the maximum value.

To fix this issue, be sure that the sequence’s maximum value is greater than the minimum value.

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2 Ways to Apply a Sequence to a Table in SQL Server

Posted on by Ian

In SQL Server, we can create sequence objects in order to generate a range of numbers that increment with each call to the sequence.

Although sequences are similar to identity columns, they are different in that they are generated independently of any table. It’s up to the application to generate the next sequence number before inserting it into the table. Therefore, we can apply a sequence to a table in the same way we would insert any other data into a table.

Here are two ways to apply sequence numbers into a table in SQL Server.

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